src/HOL/Library/Extended_Nonnegative_Real.thy
 author haftmann Fri Mar 22 19:18:08 2019 +0000 (3 months ago) changeset 69946 494934c30f38 parent 69861 62e47f06d22c child 70271 f7630118814c permissions -rw-r--r--
improved code equations taken over from AFP
```     1 (*  Title:      HOL/Library/Extended_Nonnegative_Real.thy
```
```     2     Author:     Johannes Hölzl
```
```     3 *)
```
```     4
```
```     5 subsection \<open>The type of non-negative extended real numbers\<close>
```
```     6
```
```     7 theory Extended_Nonnegative_Real
```
```     8   imports Extended_Real Indicator_Function
```
```     9 begin
```
```    10
```
```    11 lemma ereal_ineq_diff_add:
```
```    12   assumes "b \<noteq> (-\<infinity>::ereal)" "a \<ge> b"
```
```    13   shows "a = b + (a-b)"
```
```    14 by (metis add.commute assms ereal_eq_minus_iff ereal_minus_le_iff ereal_plus_eq_PInfty)
```
```    15
```
```    16 lemma Limsup_const_add:
```
```    17   fixes c :: "'a::{complete_linorder, linorder_topology, topological_monoid_add, ordered_ab_semigroup_add}"
```
```    18   shows "F \<noteq> bot \<Longrightarrow> Limsup F (\<lambda>x. c + f x) = c + Limsup F f"
```
```    19   by (rule Limsup_compose_continuous_mono)
```
```    20      (auto intro!: monoI add_mono continuous_on_add continuous_on_id continuous_on_const)
```
```    21
```
```    22 lemma Liminf_const_add:
```
```    23   fixes c :: "'a::{complete_linorder, linorder_topology, topological_monoid_add, ordered_ab_semigroup_add}"
```
```    24   shows "F \<noteq> bot \<Longrightarrow> Liminf F (\<lambda>x. c + f x) = c + Liminf F f"
```
```    25   by (rule Liminf_compose_continuous_mono)
```
```    26      (auto intro!: monoI add_mono continuous_on_add continuous_on_id continuous_on_const)
```
```    27
```
```    28 lemma Liminf_add_const:
```
```    29   fixes c :: "'a::{complete_linorder, linorder_topology, topological_monoid_add, ordered_ab_semigroup_add}"
```
```    30   shows "F \<noteq> bot \<Longrightarrow> Liminf F (\<lambda>x. f x + c) = Liminf F f + c"
```
```    31   by (rule Liminf_compose_continuous_mono)
```
```    32      (auto intro!: monoI add_mono continuous_on_add continuous_on_id continuous_on_const)
```
```    33
```
```    34 lemma sums_offset:
```
```    35   fixes f g :: "nat \<Rightarrow> 'a :: {t2_space, topological_comm_monoid_add}"
```
```    36   assumes "(\<lambda>n. f (n + i)) sums l" shows "f sums (l + (\<Sum>j<i. f j))"
```
```    37 proof  -
```
```    38   have "(\<lambda>k. (\<Sum>n<k. f (n + i)) + (\<Sum>j<i. f j)) \<longlonglongrightarrow> l + (\<Sum>j<i. f j)"
```
```    39     using assms by (auto intro!: tendsto_add simp: sums_def)
```
```    40   moreover
```
```    41   { fix k :: nat
```
```    42     have "(\<Sum>j<k + i. f j) = (\<Sum>j=i..<k + i. f j) + (\<Sum>j=0..<i. f j)"
```
```    43       by (subst sum.union_disjoint[symmetric]) (auto intro!: sum.cong)
```
```    44     also have "(\<Sum>j=i..<k + i. f j) = (\<Sum>j\<in>(\<lambda>n. n + i)`{0..<k}. f j)"
```
```    45       unfolding image_add_atLeastLessThan by simp
```
```    46     finally have "(\<Sum>j<k + i. f j) = (\<Sum>n<k. f (n + i)) + (\<Sum>j<i. f j)"
```
```    47       by (auto simp: inj_on_def atLeast0LessThan sum.reindex) }
```
```    48   ultimately have "(\<lambda>k. (\<Sum>n<k + i. f n)) \<longlonglongrightarrow> l + (\<Sum>j<i. f j)"
```
```    49     by simp
```
```    50   then show ?thesis
```
```    51     unfolding sums_def by (rule LIMSEQ_offset)
```
```    52 qed
```
```    53
```
```    54 lemma suminf_offset:
```
```    55   fixes f g :: "nat \<Rightarrow> 'a :: {t2_space, topological_comm_monoid_add}"
```
```    56   shows "summable (\<lambda>j. f (j + i)) \<Longrightarrow> suminf f = (\<Sum>j. f (j + i)) + (\<Sum>j<i. f j)"
```
```    57   by (intro sums_unique[symmetric] sums_offset summable_sums)
```
```    58
```
```    59 lemma eventually_at_left_1: "(\<And>z::real. 0 < z \<Longrightarrow> z < 1 \<Longrightarrow> P z) \<Longrightarrow> eventually P (at_left 1)"
```
```    60   by (subst eventually_at_left[of 0]) (auto intro: exI[of _ 0])
```
```    61
```
```    62 lemma mult_eq_1:
```
```    63   fixes a b :: "'a :: {ordered_semiring, comm_monoid_mult}"
```
```    64   shows "0 \<le> a \<Longrightarrow> a \<le> 1 \<Longrightarrow> b \<le> 1 \<Longrightarrow> a * b = 1 \<longleftrightarrow> (a = 1 \<and> b = 1)"
```
```    65   by (metis mult.left_neutral eq_iff mult.commute mult_right_mono)
```
```    66
```
```    67 lemma ereal_add_diff_cancel:
```
```    68   fixes a b :: ereal
```
```    69   shows "\<bar>b\<bar> \<noteq> \<infinity> \<Longrightarrow> (a + b) - b = a"
```
```    70   by (cases a b rule: ereal2_cases) auto
```
```    71
```
```    72 lemma add_top:
```
```    73   fixes x :: "'a::{order_top, ordered_comm_monoid_add}"
```
```    74   shows "0 \<le> x \<Longrightarrow> x + top = top"
```
```    75   by (intro top_le add_increasing order_refl)
```
```    76
```
```    77 lemma top_add:
```
```    78   fixes x :: "'a::{order_top, ordered_comm_monoid_add}"
```
```    79   shows "0 \<le> x \<Longrightarrow> top + x = top"
```
```    80   by (intro top_le add_increasing2 order_refl)
```
```    81
```
```    82 lemma le_lfp: "mono f \<Longrightarrow> x \<le> lfp f \<Longrightarrow> f x \<le> lfp f"
```
```    83   by (subst lfp_unfold) (auto dest: monoD)
```
```    84
```
```    85 lemma lfp_transfer:
```
```    86   assumes \<alpha>: "sup_continuous \<alpha>" and f: "sup_continuous f" and mg: "mono g"
```
```    87   assumes bot: "\<alpha> bot \<le> lfp g" and eq: "\<And>x. x \<le> lfp f \<Longrightarrow> \<alpha> (f x) = g (\<alpha> x)"
```
```    88   shows "\<alpha> (lfp f) = lfp g"
```
```    89 proof (rule antisym)
```
```    90   note mf = sup_continuous_mono[OF f]
```
```    91   have f_le_lfp: "(f ^^ i) bot \<le> lfp f" for i
```
```    92     by (induction i) (auto intro: le_lfp mf)
```
```    93
```
```    94   have "\<alpha> ((f ^^ i) bot) \<le> lfp g" for i
```
```    95     by (induction i) (auto simp: bot eq f_le_lfp intro!: le_lfp mg)
```
```    96   then show "\<alpha> (lfp f) \<le> lfp g"
```
```    97     unfolding sup_continuous_lfp[OF f]
```
```    98     by (subst \<alpha>[THEN sup_continuousD])
```
```    99        (auto intro!: mono_funpow sup_continuous_mono[OF f] SUP_least)
```
```   100
```
```   101   show "lfp g \<le> \<alpha> (lfp f)"
```
```   102     by (rule lfp_lowerbound) (simp add: eq[symmetric] lfp_fixpoint[OF mf])
```
```   103 qed
```
```   104
```
```   105 lemma sup_continuous_applyD: "sup_continuous f \<Longrightarrow> sup_continuous (\<lambda>x. f x h)"
```
```   106   using sup_continuous_apply[THEN sup_continuous_compose] .
```
```   107
```
```   108 lemma sup_continuous_SUP[order_continuous_intros]:
```
```   109   fixes M :: "_ \<Rightarrow> _ \<Rightarrow> 'a::complete_lattice"
```
```   110   assumes M: "\<And>i. i \<in> I \<Longrightarrow> sup_continuous (M i)"
```
```   111   shows  "sup_continuous (SUP i\<in>I. M i)"
```
```   112   unfolding sup_continuous_def by (auto simp add: sup_continuousD [OF M] image_comp intro: SUP_commute)
```
```   113
```
```   114 lemma sup_continuous_apply_SUP[order_continuous_intros]:
```
```   115   fixes M :: "_ \<Rightarrow> _ \<Rightarrow> 'a::complete_lattice"
```
```   116   shows "(\<And>i. i \<in> I \<Longrightarrow> sup_continuous (M i)) \<Longrightarrow> sup_continuous (\<lambda>x. SUP i\<in>I. M i x)"
```
```   117   unfolding SUP_apply[symmetric] by (rule sup_continuous_SUP)
```
```   118
```
```   119 lemma sup_continuous_lfp'[order_continuous_intros]:
```
```   120   assumes 1: "sup_continuous f"
```
```   121   assumes 2: "\<And>g. sup_continuous g \<Longrightarrow> sup_continuous (f g)"
```
```   122   shows "sup_continuous (lfp f)"
```
```   123 proof -
```
```   124   have "sup_continuous ((f ^^ i) bot)" for i
```
```   125   proof (induction i)
```
```   126     case (Suc i) then show ?case
```
```   127       by (auto intro!: 2)
```
```   128   qed (simp add: bot_fun_def sup_continuous_const)
```
```   129   then show ?thesis
```
```   130     unfolding sup_continuous_lfp[OF 1] by (intro order_continuous_intros)
```
```   131 qed
```
```   132
```
```   133 lemma sup_continuous_lfp''[order_continuous_intros]:
```
```   134   assumes 1: "\<And>s. sup_continuous (f s)"
```
```   135   assumes 2: "\<And>g. sup_continuous g \<Longrightarrow> sup_continuous (\<lambda>s. f s (g s))"
```
```   136   shows "sup_continuous (\<lambda>x. lfp (f x))"
```
```   137 proof -
```
```   138   have "sup_continuous (\<lambda>x. (f x ^^ i) bot)" for i
```
```   139   proof (induction i)
```
```   140     case (Suc i) then show ?case
```
```   141       by (auto intro!: 2)
```
```   142   qed (simp add: bot_fun_def sup_continuous_const)
```
```   143   then show ?thesis
```
```   144     unfolding sup_continuous_lfp[OF 1] by (intro order_continuous_intros)
```
```   145 qed
```
```   146
```
```   147 lemma mono_INF_fun:
```
```   148     "(\<And>x y. mono (F x y)) \<Longrightarrow> mono (\<lambda>z x. INF y \<in> X x. F x y z :: 'a :: complete_lattice)"
```
```   149   by (auto intro!: INF_mono[OF bexI] simp: le_fun_def mono_def)
```
```   150
```
```   151 lemma continuous_on_max:
```
```   152   fixes f g :: "'a::topological_space \<Rightarrow> 'b::linorder_topology"
```
```   153   shows "continuous_on A f \<Longrightarrow> continuous_on A g \<Longrightarrow> continuous_on A (\<lambda>x. max (f x) (g x))"
```
```   154   by (auto simp: continuous_on_def intro!: tendsto_max)
```
```   155
```
```   156 lemma continuous_on_cmult_ereal:
```
```   157   "\<bar>c::ereal\<bar> \<noteq> \<infinity> \<Longrightarrow> continuous_on A f \<Longrightarrow> continuous_on A (\<lambda>x. c * f x)"
```
```   158   using tendsto_cmult_ereal[of c f "f x" "at x within A" for x]
```
```   159   by (auto simp: continuous_on_def simp del: tendsto_cmult_ereal)
```
```   160
```
```   161 lemma real_of_nat_Sup:
```
```   162   assumes "A \<noteq> {}" "bdd_above A"
```
```   163   shows "of_nat (Sup A) = (SUP a\<in>A. of_nat a :: real)"
```
```   164 proof (intro antisym)
```
```   165   show "(SUP a\<in>A. of_nat a::real) \<le> of_nat (Sup A)"
```
```   166     using assms by (intro cSUP_least of_nat_mono) (auto intro: cSup_upper)
```
```   167   have "Sup A \<in> A"
```
```   168     unfolding Sup_nat_def using assms by (intro Max_in) (auto simp: bdd_above_nat)
```
```   169   then show "of_nat (Sup A) \<le> (SUP a\<in>A. of_nat a::real)"
```
```   170     by (intro cSUP_upper bdd_above_image_mono assms) (auto simp: mono_def)
```
```   171 qed
```
```   172
```
```   173 lemma (in complete_lattice) SUP_sup_const1:
```
```   174   "I \<noteq> {} \<Longrightarrow> (SUP i\<in>I. sup c (f i)) = sup c (SUP i\<in>I. f i)"
```
```   175   using SUP_sup_distrib[of "\<lambda>_. c" I f] by simp
```
```   176
```
```   177 lemma (in complete_lattice) SUP_sup_const2:
```
```   178   "I \<noteq> {} \<Longrightarrow> (SUP i\<in>I. sup (f i) c) = sup (SUP i\<in>I. f i) c"
```
```   179   using SUP_sup_distrib[of f I "\<lambda>_. c"] by simp
```
```   180
```
```   181 lemma one_less_of_natD:
```
```   182   "(1::'a::linordered_semidom) < of_nat n \<Longrightarrow> 1 < n"
```
```   183   using zero_le_one[where 'a='a]
```
```   184   apply (cases n)
```
```   185   apply simp
```
```   186   subgoal for n'
```
```   187     apply (cases n')
```
```   188     apply simp
```
```   189     apply simp
```
```   190     done
```
```   191   done
```
```   192
```
```   193 subsection \<open>Defining the extended non-negative reals\<close>
```
```   194
```
```   195 text \<open>Basic definitions and type class setup\<close>
```
```   196
```
```   197 typedef ennreal = "{x :: ereal. 0 \<le> x}"
```
```   198   morphisms enn2ereal e2ennreal'
```
```   199   by auto
```
```   200
```
```   201 definition "e2ennreal x = e2ennreal' (max 0 x)"
```
```   202
```
```   203 lemma enn2ereal_range: "e2ennreal ` {0..} = UNIV"
```
```   204 proof -
```
```   205   have "\<exists>y\<ge>0. x = e2ennreal y" for x
```
```   206     by (cases x) (auto simp: e2ennreal_def max_absorb2)
```
```   207   then show ?thesis
```
```   208     by (auto simp: image_iff Bex_def)
```
```   209 qed
```
```   210
```
```   211 lemma type_definition_ennreal': "type_definition enn2ereal e2ennreal {x. 0 \<le> x}"
```
```   212   using type_definition_ennreal
```
```   213   by (auto simp: type_definition_def e2ennreal_def max_absorb2)
```
```   214
```
```   215 setup_lifting type_definition_ennreal'
```
```   216
```
```   217 declare [[coercion e2ennreal]]
```
```   218
```
```   219 instantiation ennreal :: complete_linorder
```
```   220 begin
```
```   221
```
```   222 lift_definition top_ennreal :: ennreal is top by (rule top_greatest)
```
```   223 lift_definition bot_ennreal :: ennreal is 0 by (rule order_refl)
```
```   224 lift_definition sup_ennreal :: "ennreal \<Rightarrow> ennreal \<Rightarrow> ennreal" is sup by (rule le_supI1)
```
```   225 lift_definition inf_ennreal :: "ennreal \<Rightarrow> ennreal \<Rightarrow> ennreal" is inf by (rule le_infI)
```
```   226
```
```   227 lift_definition Inf_ennreal :: "ennreal set \<Rightarrow> ennreal" is "Inf"
```
```   228   by (rule Inf_greatest)
```
```   229
```
```   230 lift_definition Sup_ennreal :: "ennreal set \<Rightarrow> ennreal" is "sup 0 \<circ> Sup"
```
```   231   by auto
```
```   232
```
```   233 lift_definition less_eq_ennreal :: "ennreal \<Rightarrow> ennreal \<Rightarrow> bool" is "(\<le>)" .
```
```   234 lift_definition less_ennreal :: "ennreal \<Rightarrow> ennreal \<Rightarrow> bool" is "(<)" .
```
```   235
```
```   236 instance
```
```   237   by standard
```
```   238      (transfer ; auto simp: Inf_lower Inf_greatest Sup_upper Sup_least le_max_iff_disj max.absorb1)+
```
```   239
```
```   240 end
```
```   241
```
```   242 lemma pcr_ennreal_enn2ereal[simp]: "pcr_ennreal (enn2ereal x) x"
```
```   243   by (simp add: ennreal.pcr_cr_eq cr_ennreal_def)
```
```   244
```
```   245 lemma rel_fun_eq_pcr_ennreal: "rel_fun (=) pcr_ennreal f g \<longleftrightarrow> f = enn2ereal \<circ> g"
```
```   246   by (auto simp: rel_fun_def ennreal.pcr_cr_eq cr_ennreal_def)
```
```   247
```
```   248 instantiation ennreal :: infinity
```
```   249 begin
```
```   250
```
```   251 definition infinity_ennreal :: ennreal
```
```   252 where
```
```   253   [simp]: "\<infinity> = (top::ennreal)"
```
```   254
```
```   255 instance ..
```
```   256
```
```   257 end
```
```   258
```
```   259 instantiation ennreal :: "{semiring_1_no_zero_divisors, comm_semiring_1}"
```
```   260 begin
```
```   261
```
```   262 lift_definition one_ennreal :: ennreal is 1 by simp
```
```   263 lift_definition zero_ennreal :: ennreal is 0 by simp
```
```   264 lift_definition plus_ennreal :: "ennreal \<Rightarrow> ennreal \<Rightarrow> ennreal" is "(+)" by simp
```
```   265 lift_definition times_ennreal :: "ennreal \<Rightarrow> ennreal \<Rightarrow> ennreal" is "(*)" by simp
```
```   266
```
```   267 instance
```
```   268   by standard (transfer; auto simp: field_simps ereal_right_distrib)+
```
```   269
```
```   270 end
```
```   271
```
```   272 instantiation ennreal :: minus
```
```   273 begin
```
```   274
```
```   275 lift_definition minus_ennreal :: "ennreal \<Rightarrow> ennreal \<Rightarrow> ennreal" is "\<lambda>a b. max 0 (a - b)"
```
```   276   by simp
```
```   277
```
```   278 instance ..
```
```   279
```
```   280 end
```
```   281
```
```   282 instance ennreal :: numeral ..
```
```   283
```
```   284 instantiation ennreal :: inverse
```
```   285 begin
```
```   286
```
```   287 lift_definition inverse_ennreal :: "ennreal \<Rightarrow> ennreal" is inverse
```
```   288   by (rule inverse_ereal_ge0I)
```
```   289
```
```   290 definition divide_ennreal :: "ennreal \<Rightarrow> ennreal \<Rightarrow> ennreal"
```
```   291   where "x div y = x * inverse (y :: ennreal)"
```
```   292
```
```   293 instance ..
```
```   294
```
```   295 end
```
```   296
```
```   297 lemma ennreal_zero_less_one: "0 < (1::ennreal)" \<comment> \<open>TODO: remove\<close>
```
```   298   by transfer auto
```
```   299
```
```   300 instance ennreal :: dioid
```
```   301 proof (standard; transfer)
```
```   302   fix a b :: ereal assume "0 \<le> a" "0 \<le> b" then show "(a \<le> b) = (\<exists>c\<in>Collect ((\<le>) 0). b = a + c)"
```
```   303     unfolding ereal_ex_split Bex_def
```
```   304     by (cases a b rule: ereal2_cases) (auto intro!: exI[of _ "real_of_ereal (b - a)"])
```
```   305 qed
```
```   306
```
```   307 instance ennreal :: ordered_comm_semiring
```
```   308   by standard
```
```   309      (transfer ; auto intro: add_mono mult_mono mult_ac ereal_left_distrib ereal_mult_left_mono)+
```
```   310
```
```   311 instance ennreal :: linordered_nonzero_semiring
```
```   312 proof
```
```   313   fix a b::ennreal
```
```   314   show "a < b \<Longrightarrow> a + 1 < b + 1"
```
```   315     by transfer (simp add: add_right_mono ereal_add_cancel_right less_le)
```
```   316 qed (transfer; simp)
```
```   317
```
```   318 instance ennreal :: strict_ordered_ab_semigroup_add
```
```   319 proof
```
```   320   fix a b c d :: ennreal show "a < b \<Longrightarrow> c < d \<Longrightarrow> a + c < b + d"
```
```   321     by transfer (auto intro!: ereal_add_strict_mono)
```
```   322 qed
```
```   323
```
```   324 declare [[coercion "of_nat :: nat \<Rightarrow> ennreal"]]
```
```   325
```
```   326 lemma e2ennreal_neg: "x \<le> 0 \<Longrightarrow> e2ennreal x = 0"
```
```   327   unfolding zero_ennreal_def e2ennreal_def by (simp add: max_absorb1)
```
```   328
```
```   329 lemma e2ennreal_mono: "x \<le> y \<Longrightarrow> e2ennreal x \<le> e2ennreal y"
```
```   330   by (cases "0 \<le> x" "0 \<le> y" rule: bool.exhaust[case_product bool.exhaust])
```
```   331      (auto simp: e2ennreal_neg less_eq_ennreal.abs_eq eq_onp_def)
```
```   332
```
```   333 lemma enn2ereal_nonneg[simp]: "0 \<le> enn2ereal x"
```
```   334   using ennreal.enn2ereal[of x] by simp
```
```   335
```
```   336 lemma ereal_ennreal_cases:
```
```   337   obtains b where "0 \<le> a" "a = enn2ereal b" | "a < 0"
```
```   338   using e2ennreal'_inverse[of a, symmetric] by (cases "0 \<le> a") (auto intro: enn2ereal_nonneg)
```
```   339
```
```   340 lemma rel_fun_liminf[transfer_rule]: "rel_fun (rel_fun (=) pcr_ennreal) pcr_ennreal liminf liminf"
```
```   341 proof -
```
```   342   have "rel_fun (rel_fun (=) pcr_ennreal) pcr_ennreal (\<lambda>x. sup 0 (liminf x)) liminf"
```
```   343     unfolding liminf_SUP_INF[abs_def] by (transfer_prover_start, transfer_step+; simp)
```
```   344   then show ?thesis
```
```   345     apply (subst (asm) (2) rel_fun_def)
```
```   346     apply (subst (2) rel_fun_def)
```
```   347     apply (auto simp: comp_def max.absorb2 Liminf_bounded rel_fun_eq_pcr_ennreal)
```
```   348     done
```
```   349 qed
```
```   350
```
```   351 lemma rel_fun_limsup[transfer_rule]: "rel_fun (rel_fun (=) pcr_ennreal) pcr_ennreal limsup limsup"
```
```   352 proof -
```
```   353   have "rel_fun (rel_fun (=) pcr_ennreal) pcr_ennreal (\<lambda>x. INF n. sup 0 (SUP i\<in>{n..}. x i)) limsup"
```
```   354     unfolding limsup_INF_SUP[abs_def] by (transfer_prover_start, transfer_step+; simp)
```
```   355   then show ?thesis
```
```   356     unfolding limsup_INF_SUP[abs_def]
```
```   357     apply (subst (asm) (2) rel_fun_def)
```
```   358     apply (subst (2) rel_fun_def)
```
```   359     apply (auto simp: comp_def max.absorb2 Sup_upper2 rel_fun_eq_pcr_ennreal)
```
```   360     apply (subst (asm) max.absorb2)
```
```   361     apply (rule SUP_upper2)
```
```   362     apply auto
```
```   363     done
```
```   364 qed
```
```   365
```
```   366 lemma sum_enn2ereal[simp]: "(\<And>i. i \<in> I \<Longrightarrow> 0 \<le> f i) \<Longrightarrow> (\<Sum>i\<in>I. enn2ereal (f i)) = enn2ereal (sum f I)"
```
```   367   by (induction I rule: infinite_finite_induct) (auto simp: sum_nonneg zero_ennreal.rep_eq plus_ennreal.rep_eq)
```
```   368
```
```   369 lemma transfer_e2ennreal_sum [transfer_rule]:
```
```   370   "rel_fun (rel_fun (=) pcr_ennreal) (rel_fun (=) pcr_ennreal) sum sum"
```
```   371   by (auto intro!: rel_funI simp: rel_fun_eq_pcr_ennreal comp_def)
```
```   372
```
```   373 lemma enn2ereal_of_nat[simp]: "enn2ereal (of_nat n) = ereal n"
```
```   374   by (induction n) (auto simp: zero_ennreal.rep_eq one_ennreal.rep_eq plus_ennreal.rep_eq)
```
```   375
```
```   376 lemma enn2ereal_numeral[simp]: "enn2ereal (numeral a) = numeral a"
```
```   377   apply (subst of_nat_numeral[of a, symmetric])
```
```   378   apply (subst enn2ereal_of_nat)
```
```   379   apply simp
```
```   380   done
```
```   381
```
```   382 lemma transfer_numeral[transfer_rule]: "pcr_ennreal (numeral a) (numeral a)"
```
```   383   unfolding cr_ennreal_def pcr_ennreal_def by auto
```
```   384
```
```   385 subsection \<open>Cancellation simprocs\<close>
```
```   386
```
```   387 lemma ennreal_add_left_cancel: "a + b = a + c \<longleftrightarrow> a = (\<infinity>::ennreal) \<or> b = c"
```
```   388   unfolding infinity_ennreal_def by transfer (simp add: top_ereal_def ereal_add_cancel_left)
```
```   389
```
```   390 lemma ennreal_add_left_cancel_le: "a + b \<le> a + c \<longleftrightarrow> a = (\<infinity>::ennreal) \<or> b \<le> c"
```
```   391   unfolding infinity_ennreal_def by transfer (simp add: ereal_add_le_add_iff top_ereal_def disj_commute)
```
```   392
```
```   393 lemma ereal_add_left_cancel_less:
```
```   394   fixes a b c :: ereal
```
```   395   shows "0 \<le> a \<Longrightarrow> 0 \<le> b \<Longrightarrow> a + b < a + c \<longleftrightarrow> a \<noteq> \<infinity> \<and> b < c"
```
```   396   by (cases a b c rule: ereal3_cases) auto
```
```   397
```
```   398 lemma ennreal_add_left_cancel_less: "a + b < a + c \<longleftrightarrow> a \<noteq> (\<infinity>::ennreal) \<and> b < c"
```
```   399   unfolding infinity_ennreal_def
```
```   400   by transfer (simp add: top_ereal_def ereal_add_left_cancel_less)
```
```   401
```
```   402 ML \<open>
```
```   403 structure Cancel_Ennreal_Common =
```
```   404 struct
```
```   405   (* copied from src/HOL/Tools/nat_numeral_simprocs.ML *)
```
```   406   fun find_first_t _    _ []         = raise TERM("find_first_t", [])
```
```   407     | find_first_t past u (t::terms) =
```
```   408           if u aconv t then (rev past @ terms)
```
```   409           else find_first_t (t::past) u terms
```
```   410
```
```   411   fun dest_summing (Const (\<^const_name>\<open>Groups.plus\<close>, _) \$ t \$ u, ts) =
```
```   412         dest_summing (t, dest_summing (u, ts))
```
```   413     | dest_summing (t, ts) = t :: ts
```
```   414
```
```   415   val mk_sum = Arith_Data.long_mk_sum
```
```   416   fun dest_sum t = dest_summing (t, [])
```
```   417   val find_first = find_first_t []
```
```   418   val trans_tac = Numeral_Simprocs.trans_tac
```
```   419   val norm_ss =
```
```   420     simpset_of (put_simpset HOL_basic_ss \<^context>
```
```   421       addsimps @{thms ac_simps add_0_left add_0_right})
```
```   422   fun norm_tac ctxt = ALLGOALS (simp_tac (put_simpset norm_ss ctxt))
```
```   423   fun simplify_meta_eq ctxt cancel_th th =
```
```   424     Arith_Data.simplify_meta_eq [] ctxt
```
```   425       ([th, cancel_th] MRS trans)
```
```   426   fun mk_eq (a, b) = HOLogic.mk_Trueprop (HOLogic.mk_eq (a, b))
```
```   427 end
```
```   428
```
```   429 structure Eq_Ennreal_Cancel = ExtractCommonTermFun
```
```   430 (open Cancel_Ennreal_Common
```
```   431   val mk_bal = HOLogic.mk_eq
```
```   432   val dest_bal = HOLogic.dest_bin \<^const_name>\<open>HOL.eq\<close> \<^typ>\<open>ennreal\<close>
```
```   433   fun simp_conv _ _ = SOME @{thm ennreal_add_left_cancel}
```
```   434 )
```
```   435
```
```   436 structure Le_Ennreal_Cancel = ExtractCommonTermFun
```
```   437 (open Cancel_Ennreal_Common
```
```   438   val mk_bal = HOLogic.mk_binrel \<^const_name>\<open>Orderings.less_eq\<close>
```
```   439   val dest_bal = HOLogic.dest_bin \<^const_name>\<open>Orderings.less_eq\<close> \<^typ>\<open>ennreal\<close>
```
```   440   fun simp_conv _ _ = SOME @{thm ennreal_add_left_cancel_le}
```
```   441 )
```
```   442
```
```   443 structure Less_Ennreal_Cancel = ExtractCommonTermFun
```
```   444 (open Cancel_Ennreal_Common
```
```   445   val mk_bal = HOLogic.mk_binrel \<^const_name>\<open>Orderings.less\<close>
```
```   446   val dest_bal = HOLogic.dest_bin \<^const_name>\<open>Orderings.less\<close> \<^typ>\<open>ennreal\<close>
```
```   447   fun simp_conv _ _ = SOME @{thm ennreal_add_left_cancel_less}
```
```   448 )
```
```   449 \<close>
```
```   450
```
```   451 simproc_setup ennreal_eq_cancel
```
```   452   ("(l::ennreal) + m = n" | "(l::ennreal) = m + n") =
```
```   453   \<open>fn phi => fn ctxt => fn ct => Eq_Ennreal_Cancel.proc ctxt (Thm.term_of ct)\<close>
```
```   454
```
```   455 simproc_setup ennreal_le_cancel
```
```   456   ("(l::ennreal) + m \<le> n" | "(l::ennreal) \<le> m + n") =
```
```   457   \<open>fn phi => fn ctxt => fn ct => Le_Ennreal_Cancel.proc ctxt (Thm.term_of ct)\<close>
```
```   458
```
```   459 simproc_setup ennreal_less_cancel
```
```   460   ("(l::ennreal) + m < n" | "(l::ennreal) < m + n") =
```
```   461   \<open>fn phi => fn ctxt => fn ct => Less_Ennreal_Cancel.proc ctxt (Thm.term_of ct)\<close>
```
```   462
```
```   463
```
```   464 subsection \<open>Order with top\<close>
```
```   465
```
```   466 lemma ennreal_zero_less_top[simp]: "0 < (top::ennreal)"
```
```   467   by transfer (simp add: top_ereal_def)
```
```   468
```
```   469 lemma ennreal_one_less_top[simp]: "1 < (top::ennreal)"
```
```   470   by transfer (simp add: top_ereal_def)
```
```   471
```
```   472 lemma ennreal_zero_neq_top[simp]: "0 \<noteq> (top::ennreal)"
```
```   473   by transfer (simp add: top_ereal_def)
```
```   474
```
```   475 lemma ennreal_top_neq_zero[simp]: "(top::ennreal) \<noteq> 0"
```
```   476   by transfer (simp add: top_ereal_def)
```
```   477
```
```   478 lemma ennreal_top_neq_one[simp]: "top \<noteq> (1::ennreal)"
```
```   479   by transfer (simp add: top_ereal_def one_ereal_def flip: ereal_max)
```
```   480
```
```   481 lemma ennreal_one_neq_top[simp]: "1 \<noteq> (top::ennreal)"
```
```   482   by transfer (simp add: top_ereal_def one_ereal_def flip: ereal_max)
```
```   483
```
```   484 lemma ennreal_add_less_top[simp]:
```
```   485   fixes a b :: ennreal
```
```   486   shows "a + b < top \<longleftrightarrow> a < top \<and> b < top"
```
```   487   by transfer (auto simp: top_ereal_def)
```
```   488
```
```   489 lemma ennreal_add_eq_top[simp]:
```
```   490   fixes a b :: ennreal
```
```   491   shows "a + b = top \<longleftrightarrow> a = top \<or> b = top"
```
```   492   by transfer (auto simp: top_ereal_def)
```
```   493
```
```   494 lemma ennreal_sum_less_top[simp]:
```
```   495   fixes f :: "'a \<Rightarrow> ennreal"
```
```   496   shows "finite I \<Longrightarrow> (\<Sum>i\<in>I. f i) < top \<longleftrightarrow> (\<forall>i\<in>I. f i < top)"
```
```   497   by (induction I rule: finite_induct) auto
```
```   498
```
```   499 lemma ennreal_sum_eq_top[simp]:
```
```   500   fixes f :: "'a \<Rightarrow> ennreal"
```
```   501   shows "finite I \<Longrightarrow> (\<Sum>i\<in>I. f i) = top \<longleftrightarrow> (\<exists>i\<in>I. f i = top)"
```
```   502   by (induction I rule: finite_induct) auto
```
```   503
```
```   504 lemma ennreal_mult_eq_top_iff:
```
```   505   fixes a b :: ennreal
```
```   506   shows "a * b = top \<longleftrightarrow> (a = top \<and> b \<noteq> 0) \<or> (b = top \<and> a \<noteq> 0)"
```
```   507   by transfer (auto simp: top_ereal_def)
```
```   508
```
```   509 lemma ennreal_top_eq_mult_iff:
```
```   510   fixes a b :: ennreal
```
```   511   shows "top = a * b \<longleftrightarrow> (a = top \<and> b \<noteq> 0) \<or> (b = top \<and> a \<noteq> 0)"
```
```   512   using ennreal_mult_eq_top_iff[of a b] by auto
```
```   513
```
```   514 lemma ennreal_mult_less_top:
```
```   515   fixes a b :: ennreal
```
```   516   shows "a * b < top \<longleftrightarrow> (a = 0 \<or> b = 0 \<or> (a < top \<and> b < top))"
```
```   517   by transfer (auto simp add: top_ereal_def)
```
```   518
```
```   519 lemma top_power_ennreal: "top ^ n = (if n = 0 then 1 else top :: ennreal)"
```
```   520   by (induction n) (simp_all add: ennreal_mult_eq_top_iff)
```
```   521
```
```   522 lemma ennreal_prod_eq_0[simp]:
```
```   523   fixes f :: "'a \<Rightarrow> ennreal"
```
```   524   shows "(prod f A = 0) = (finite A \<and> (\<exists>i\<in>A. f i = 0))"
```
```   525   by (induction A rule: infinite_finite_induct) auto
```
```   526
```
```   527 lemma ennreal_prod_eq_top:
```
```   528   fixes f :: "'a \<Rightarrow> ennreal"
```
```   529   shows "(\<Prod>i\<in>I. f i) = top \<longleftrightarrow> (finite I \<and> ((\<forall>i\<in>I. f i \<noteq> 0) \<and> (\<exists>i\<in>I. f i = top)))"
```
```   530   by (induction I rule: infinite_finite_induct) (auto simp: ennreal_mult_eq_top_iff)
```
```   531
```
```   532 lemma ennreal_top_mult: "top * a = (if a = 0 then 0 else top :: ennreal)"
```
```   533   by (simp add: ennreal_mult_eq_top_iff)
```
```   534
```
```   535 lemma ennreal_mult_top: "a * top = (if a = 0 then 0 else top :: ennreal)"
```
```   536   by (simp add: ennreal_mult_eq_top_iff)
```
```   537
```
```   538 lemma enn2ereal_eq_top_iff[simp]: "enn2ereal x = \<infinity> \<longleftrightarrow> x = top"
```
```   539   by transfer (simp add: top_ereal_def)
```
```   540
```
```   541 lemma enn2ereal_top[simp]: "enn2ereal top = \<infinity>"
```
```   542   by transfer (simp add: top_ereal_def)
```
```   543
```
```   544 lemma e2ennreal_infty[simp]: "e2ennreal \<infinity> = top"
```
```   545   by (simp add: top_ennreal.abs_eq top_ereal_def)
```
```   546
```
```   547 lemma ennreal_top_minus[simp]: "top - x = (top::ennreal)"
```
```   548   by transfer (auto simp: top_ereal_def max_def)
```
```   549
```
```   550 lemma minus_top_ennreal: "x - top = (if x = top then top else 0:: ennreal)"
```
```   551   apply transfer
```
```   552   subgoal for x
```
```   553     by (cases x) (auto simp: top_ereal_def max_def)
```
```   554   done
```
```   555
```
```   556 lemma bot_ennreal: "bot = (0::ennreal)"
```
```   557   by transfer rule
```
```   558
```
```   559 lemma ennreal_of_nat_neq_top[simp]: "of_nat i \<noteq> (top::ennreal)"
```
```   560   by (induction i) auto
```
```   561
```
```   562 lemma numeral_eq_of_nat: "(numeral a::ennreal) = of_nat (numeral a)"
```
```   563   by simp
```
```   564
```
```   565 lemma of_nat_less_top: "of_nat i < (top::ennreal)"
```
```   566   using less_le_trans[of "of_nat i" "of_nat (Suc i)" "top::ennreal"]
```
```   567   by simp
```
```   568
```
```   569 lemma top_neq_numeral[simp]: "top \<noteq> (numeral i::ennreal)"
```
```   570   using of_nat_less_top[of "numeral i"] by simp
```
```   571
```
```   572 lemma ennreal_numeral_less_top[simp]: "numeral i < (top::ennreal)"
```
```   573   using of_nat_less_top[of "numeral i"] by simp
```
```   574
```
```   575 lemma ennreal_add_bot[simp]: "bot + x = (x::ennreal)"
```
```   576   by transfer simp
```
```   577
```
```   578 instance ennreal :: semiring_char_0
```
```   579 proof (standard, safe intro!: linorder_injI)
```
```   580   have *: "1 + of_nat k \<noteq> (0::ennreal)" for k
```
```   581     using add_pos_nonneg[OF zero_less_one, of "of_nat k :: ennreal"] by auto
```
```   582   fix x y :: nat assume "x < y" "of_nat x = (of_nat y::ennreal)" then show False
```
```   583     by (auto simp add: less_iff_Suc_add *)
```
```   584 qed
```
```   585
```
```   586 subsection \<open>Arithmetic\<close>
```
```   587
```
```   588 lemma ennreal_minus_zero[simp]: "a - (0::ennreal) = a"
```
```   589   by transfer (auto simp: max_def)
```
```   590
```
```   591 lemma ennreal_add_diff_cancel_right[simp]:
```
```   592   fixes x y z :: ennreal shows "y \<noteq> top \<Longrightarrow> (x + y) - y = x"
```
```   593   apply transfer
```
```   594   subgoal for x y
```
```   595     apply (cases x y rule: ereal2_cases)
```
```   596     apply (auto split: split_max simp: top_ereal_def)
```
```   597     done
```
```   598   done
```
```   599
```
```   600 lemma ennreal_add_diff_cancel_left[simp]:
```
```   601   fixes x y z :: ennreal shows "y \<noteq> top \<Longrightarrow> (y + x) - y = x"
```
```   602   by (simp add: add.commute)
```
```   603
```
```   604 lemma
```
```   605   fixes a b :: ennreal
```
```   606   shows "a - b = 0 \<Longrightarrow> a \<le> b"
```
```   607   apply transfer
```
```   608   subgoal for a b
```
```   609     apply (cases a b rule: ereal2_cases)
```
```   610     apply (auto simp: not_le max_def split: if_splits)
```
```   611     done
```
```   612   done
```
```   613
```
```   614 lemma ennreal_minus_cancel:
```
```   615   fixes a b c :: ennreal
```
```   616   shows "c \<noteq> top \<Longrightarrow> a \<le> c \<Longrightarrow> b \<le> c \<Longrightarrow> c - a = c - b \<Longrightarrow> a = b"
```
```   617   apply transfer
```
```   618   subgoal for a b c
```
```   619     by (cases a b c rule: ereal3_cases)
```
```   620        (auto simp: top_ereal_def max_def split: if_splits)
```
```   621   done
```
```   622
```
```   623 lemma sup_const_add_ennreal:
```
```   624   fixes a b c :: "ennreal"
```
```   625   shows "sup (c + a) (c + b) = c + sup a b"
```
```   626   apply transfer
```
```   627   subgoal for a b c
```
```   628     apply (cases a b c rule: ereal3_cases)
```
```   629     apply (auto simp flip: ereal_max)
```
```   630     done
```
```   631   done
```
```   632
```
```   633 lemma ennreal_diff_add_assoc:
```
```   634   fixes a b c :: ennreal
```
```   635   shows "a \<le> b \<Longrightarrow> c + b - a = c + (b - a)"
```
```   636   apply transfer
```
```   637   subgoal for a b c
```
```   638     by (cases a b c rule: ereal3_cases) (auto simp: field_simps max_absorb2)
```
```   639   done
```
```   640
```
```   641 lemma mult_divide_eq_ennreal:
```
```   642   fixes a b :: ennreal
```
```   643   shows "b \<noteq> 0 \<Longrightarrow> b \<noteq> top \<Longrightarrow> (a * b) / b = a"
```
```   644   unfolding divide_ennreal_def
```
```   645   apply transfer
```
```   646   apply (subst mult.assoc)
```
```   647   apply (simp add: top_ereal_def flip: divide_ereal_def)
```
```   648   done
```
```   649
```
```   650 lemma divide_mult_eq: "a \<noteq> 0 \<Longrightarrow> a \<noteq> \<infinity> \<Longrightarrow> x * a / (b * a) = x / (b::ennreal)"
```
```   651   unfolding divide_ennreal_def infinity_ennreal_def
```
```   652   apply transfer
```
```   653   subgoal for a b c
```
```   654     apply (cases a b c rule: ereal3_cases)
```
```   655     apply (auto simp: top_ereal_def)
```
```   656     done
```
```   657   done
```
```   658
```
```   659 lemma ennreal_mult_divide_eq:
```
```   660   fixes a b :: ennreal
```
```   661   shows "b \<noteq> 0 \<Longrightarrow> b \<noteq> top \<Longrightarrow> (a * b) / b = a"
```
```   662   unfolding divide_ennreal_def
```
```   663   apply transfer
```
```   664   apply (subst mult.assoc)
```
```   665   apply (simp add: top_ereal_def flip: divide_ereal_def)
```
```   666   done
```
```   667
```
```   668 lemma ennreal_add_diff_cancel:
```
```   669   fixes a b :: ennreal
```
```   670   shows "b \<noteq> \<infinity> \<Longrightarrow> (a + b) - b = a"
```
```   671   unfolding infinity_ennreal_def
```
```   672   by transfer (simp add: max_absorb2 top_ereal_def ereal_add_diff_cancel)
```
```   673
```
```   674 lemma ennreal_minus_eq_0:
```
```   675   "a - b = 0 \<Longrightarrow> a \<le> (b::ennreal)"
```
```   676   apply transfer
```
```   677   subgoal for a b
```
```   678     apply (cases a b rule: ereal2_cases)
```
```   679     apply (auto simp: zero_ereal_def max.absorb2 simp flip: ereal_max)
```
```   680     done
```
```   681   done
```
```   682
```
```   683 lemma ennreal_mono_minus_cancel:
```
```   684   fixes a b c :: ennreal
```
```   685   shows "a - b \<le> a - c \<Longrightarrow> a < top \<Longrightarrow> b \<le> a \<Longrightarrow> c \<le> a \<Longrightarrow> c \<le> b"
```
```   686   by transfer
```
```   687      (auto simp add: max.absorb2 ereal_diff_positive top_ereal_def dest: ereal_mono_minus_cancel)
```
```   688
```
```   689 lemma ennreal_mono_minus:
```
```   690   fixes a b c :: ennreal
```
```   691   shows "c \<le> b \<Longrightarrow> a - b \<le> a - c"
```
```   692   apply transfer
```
```   693   apply (rule max.mono)
```
```   694   apply simp
```
```   695   subgoal for a b c
```
```   696     by (cases a b c rule: ereal3_cases) auto
```
```   697   done
```
```   698
```
```   699 lemma ennreal_minus_pos_iff:
```
```   700   fixes a b :: ennreal
```
```   701   shows "a < top \<or> b < top \<Longrightarrow> 0 < a - b \<Longrightarrow> b < a"
```
```   702   apply transfer
```
```   703   subgoal for a b
```
```   704     by (cases a b rule: ereal2_cases) (auto simp: less_max_iff_disj)
```
```   705   done
```
```   706
```
```   707 lemma ennreal_inverse_top[simp]: "inverse top = (0::ennreal)"
```
```   708   by transfer (simp add: top_ereal_def ereal_inverse_eq_0)
```
```   709
```
```   710 lemma ennreal_inverse_zero[simp]: "inverse 0 = (top::ennreal)"
```
```   711   by transfer (simp add: top_ereal_def ereal_inverse_eq_0)
```
```   712
```
```   713 lemma ennreal_top_divide: "top / (x::ennreal) = (if x = top then 0 else top)"
```
```   714   unfolding divide_ennreal_def
```
```   715   by transfer (simp add: top_ereal_def ereal_inverse_eq_0 ereal_0_gt_inverse)
```
```   716
```
```   717 lemma ennreal_zero_divide[simp]: "0 / (x::ennreal) = 0"
```
```   718   by (simp add: divide_ennreal_def)
```
```   719
```
```   720 lemma ennreal_divide_zero[simp]: "x / (0::ennreal) = (if x = 0 then 0 else top)"
```
```   721   by (simp add: divide_ennreal_def ennreal_mult_top)
```
```   722
```
```   723 lemma ennreal_divide_top[simp]: "x / (top::ennreal) = 0"
```
```   724   by (simp add: divide_ennreal_def ennreal_top_mult)
```
```   725
```
```   726 lemma ennreal_times_divide: "a * (b / c) = a * b / (c::ennreal)"
```
```   727   unfolding divide_ennreal_def
```
```   728   by transfer (simp add: divide_ereal_def[symmetric] ereal_times_divide_eq)
```
```   729
```
```   730 lemma ennreal_zero_less_divide: "0 < a / b \<longleftrightarrow> (0 < a \<and> b < (top::ennreal))"
```
```   731   unfolding divide_ennreal_def
```
```   732   by transfer (auto simp: ereal_zero_less_0_iff top_ereal_def ereal_0_gt_inverse)
```
```   733
```
```   734 lemma divide_right_mono_ennreal:
```
```   735   fixes a b c :: ennreal
```
```   736   shows "a \<le> b \<Longrightarrow> a / c \<le> b / c"
```
```   737   unfolding divide_ennreal_def by (intro mult_mono) auto
```
```   738
```
```   739 lemma ennreal_mult_strict_right_mono: "(a::ennreal) < c \<Longrightarrow> 0 < b \<Longrightarrow> b < top \<Longrightarrow> a * b < c * b"
```
```   740   by transfer (auto intro!: ereal_mult_strict_right_mono)
```
```   741
```
```   742 lemma ennreal_indicator_less[simp]:
```
```   743   "indicator A x \<le> (indicator B x::ennreal) \<longleftrightarrow> (x \<in> A \<longrightarrow> x \<in> B)"
```
```   744   by (simp add: indicator_def not_le)
```
```   745
```
```   746 lemma ennreal_inverse_positive: "0 < inverse x \<longleftrightarrow> (x::ennreal) \<noteq> top"
```
```   747   by transfer (simp add: ereal_0_gt_inverse top_ereal_def)
```
```   748
```
```   749 lemma ennreal_inverse_mult': "((0 < b \<or> a < top) \<and> (0 < a \<or> b < top)) \<Longrightarrow> inverse (a * b::ennreal) = inverse a * inverse b"
```
```   750   apply transfer
```
```   751   subgoal for a b
```
```   752     by (cases a b rule: ereal2_cases) (auto simp: top_ereal_def)
```
```   753   done
```
```   754
```
```   755 lemma ennreal_inverse_mult: "a < top \<Longrightarrow> b < top \<Longrightarrow> inverse (a * b::ennreal) = inverse a * inverse b"
```
```   756   apply transfer
```
```   757   subgoal for a b
```
```   758     by (cases a b rule: ereal2_cases) (auto simp: top_ereal_def)
```
```   759   done
```
```   760
```
```   761 lemma ennreal_inverse_1[simp]: "inverse (1::ennreal) = 1"
```
```   762   by transfer simp
```
```   763
```
```   764 lemma ennreal_inverse_eq_0_iff[simp]: "inverse (a::ennreal) = 0 \<longleftrightarrow> a = top"
```
```   765   by transfer (simp add: ereal_inverse_eq_0 top_ereal_def)
```
```   766
```
```   767 lemma ennreal_inverse_eq_top_iff[simp]: "inverse (a::ennreal) = top \<longleftrightarrow> a = 0"
```
```   768   by transfer (simp add: top_ereal_def)
```
```   769
```
```   770 lemma ennreal_divide_eq_0_iff[simp]: "(a::ennreal) / b = 0 \<longleftrightarrow> (a = 0 \<or> b = top)"
```
```   771   by (simp add: divide_ennreal_def)
```
```   772
```
```   773 lemma ennreal_divide_eq_top_iff: "(a::ennreal) / b = top \<longleftrightarrow> ((a \<noteq> 0 \<and> b = 0) \<or> (a = top \<and> b \<noteq> top))"
```
```   774   by (auto simp add: divide_ennreal_def ennreal_mult_eq_top_iff)
```
```   775
```
```   776 lemma one_divide_one_divide_ennreal[simp]: "1 / (1 / c) = (c::ennreal)"
```
```   777   including ennreal.lifting
```
```   778   unfolding divide_ennreal_def
```
```   779   by transfer auto
```
```   780
```
```   781 lemma ennreal_mult_left_cong:
```
```   782   "((a::ennreal) \<noteq> 0 \<Longrightarrow> b = c) \<Longrightarrow> a * b = a * c"
```
```   783   by (cases "a = 0") simp_all
```
```   784
```
```   785 lemma ennreal_mult_right_cong:
```
```   786   "((a::ennreal) \<noteq> 0 \<Longrightarrow> b = c) \<Longrightarrow> b * a = c * a"
```
```   787   by (cases "a = 0") simp_all
```
```   788
```
```   789 lemma ennreal_zero_less_mult_iff: "0 < a * b \<longleftrightarrow> 0 < a \<and> 0 < (b::ennreal)"
```
```   790   by transfer (auto simp add: ereal_zero_less_0_iff le_less)
```
```   791
```
```   792 lemma less_diff_eq_ennreal:
```
```   793   fixes a b c :: ennreal
```
```   794   shows "b < top \<or> c < top \<Longrightarrow> a < b - c \<longleftrightarrow> a + c < b"
```
```   795   apply transfer
```
```   796   subgoal for a b c
```
```   797     by (cases a b c rule: ereal3_cases) (auto split: split_max)
```
```   798   done
```
```   799
```
```   800 lemma diff_add_cancel_ennreal:
```
```   801   fixes a b :: ennreal shows "a \<le> b \<Longrightarrow> b - a + a = b"
```
```   802   unfolding infinity_ennreal_def
```
```   803   apply transfer
```
```   804   subgoal for a b
```
```   805     by (cases a b rule: ereal2_cases) (auto simp: max_absorb2)
```
```   806   done
```
```   807
```
```   808 lemma ennreal_diff_self[simp]: "a \<noteq> top \<Longrightarrow> a - a = (0::ennreal)"
```
```   809   by transfer (simp add: top_ereal_def)
```
```   810
```
```   811 lemma ennreal_minus_mono:
```
```   812   fixes a b c :: ennreal
```
```   813   shows "a \<le> c \<Longrightarrow> d \<le> b \<Longrightarrow> a - b \<le> c - d"
```
```   814   apply transfer
```
```   815   apply (rule max.mono)
```
```   816   apply simp
```
```   817   subgoal for a b c d
```
```   818     by (cases a b c d rule: ereal3_cases[case_product ereal_cases]) auto
```
```   819   done
```
```   820
```
```   821 lemma ennreal_minus_eq_top[simp]: "a - (b::ennreal) = top \<longleftrightarrow> a = top"
```
```   822   by transfer (auto simp: top_ereal_def max.absorb2 ereal_minus_eq_PInfty_iff split: split_max)
```
```   823
```
```   824 lemma ennreal_divide_self[simp]: "a \<noteq> 0 \<Longrightarrow> a < top \<Longrightarrow> a / a = (1::ennreal)"
```
```   825   unfolding divide_ennreal_def
```
```   826   apply transfer
```
```   827   subgoal for a
```
```   828     by (cases a) (auto simp: top_ereal_def)
```
```   829   done
```
```   830
```
```   831 subsection \<open>Coercion from \<^typ>\<open>real\<close> to \<^typ>\<open>ennreal\<close>\<close>
```
```   832
```
```   833 lift_definition ennreal :: "real \<Rightarrow> ennreal" is "sup 0 \<circ> ereal"
```
```   834   by simp
```
```   835
```
```   836 declare [[coercion ennreal]]
```
```   837
```
```   838 lemma ennreal_cong: "x = y \<Longrightarrow> ennreal x = ennreal y" by simp
```
```   839
```
```   840 lemma ennreal_cases[cases type: ennreal]:
```
```   841   fixes x :: ennreal
```
```   842   obtains (real) r :: real where "0 \<le> r" "x = ennreal r" | (top) "x = top"
```
```   843   apply transfer
```
```   844   subgoal for x thesis
```
```   845     by (cases x) (auto simp: max.absorb2 top_ereal_def)
```
```   846   done
```
```   847
```
```   848 lemmas ennreal2_cases = ennreal_cases[case_product ennreal_cases]
```
```   849 lemmas ennreal3_cases = ennreal_cases[case_product ennreal2_cases]
```
```   850
```
```   851 lemma ennreal_neq_top[simp]: "ennreal r \<noteq> top"
```
```   852   by transfer (simp add: top_ereal_def zero_ereal_def flip: ereal_max)
```
```   853
```
```   854 lemma top_neq_ennreal[simp]: "top \<noteq> ennreal r"
```
```   855   using ennreal_neq_top[of r] by (auto simp del: ennreal_neq_top)
```
```   856
```
```   857 lemma ennreal_less_top[simp]: "ennreal x < top"
```
```   858   by transfer (simp add: top_ereal_def max_def)
```
```   859
```
```   860 lemma ennreal_neg: "x \<le> 0 \<Longrightarrow> ennreal x = 0"
```
```   861   by transfer (simp add: max.absorb1)
```
```   862
```
```   863 lemma ennreal_inj[simp]:
```
```   864   "0 \<le> a \<Longrightarrow> 0 \<le> b \<Longrightarrow> ennreal a = ennreal b \<longleftrightarrow> a = b"
```
```   865   by (transfer fixing: a b) (auto simp: max_absorb2)
```
```   866
```
```   867 lemma ennreal_le_iff[simp]: "0 \<le> y \<Longrightarrow> ennreal x \<le> ennreal y \<longleftrightarrow> x \<le> y"
```
```   868   by (auto simp: ennreal_def zero_ereal_def less_eq_ennreal.abs_eq eq_onp_def split: split_max)
```
```   869
```
```   870 lemma le_ennreal_iff: "0 \<le> r \<Longrightarrow> x \<le> ennreal r \<longleftrightarrow> (\<exists>q\<ge>0. x = ennreal q \<and> q \<le> r)"
```
```   871   by (cases x) (auto simp: top_unique)
```
```   872
```
```   873 lemma ennreal_less_iff: "0 \<le> r \<Longrightarrow> ennreal r < ennreal q \<longleftrightarrow> r < q"
```
```   874   unfolding not_le[symmetric] by auto
```
```   875
```
```   876 lemma ennreal_eq_zero_iff[simp]: "0 \<le> x \<Longrightarrow> ennreal x = 0 \<longleftrightarrow> x = 0"
```
```   877   by transfer (auto simp: max_absorb2)
```
```   878
```
```   879 lemma ennreal_less_zero_iff[simp]: "0 < ennreal x \<longleftrightarrow> 0 < x"
```
```   880   by transfer (auto simp: max_def)
```
```   881
```
```   882 lemma ennreal_lessI: "0 < q \<Longrightarrow> r < q \<Longrightarrow> ennreal r < ennreal q"
```
```   883   by (cases "0 \<le> r") (auto simp: ennreal_less_iff ennreal_neg)
```
```   884
```
```   885 lemma ennreal_leI: "x \<le> y \<Longrightarrow> ennreal x \<le> ennreal y"
```
```   886   by (cases "0 \<le> y") (auto simp: ennreal_neg)
```
```   887
```
```   888 lemma enn2ereal_ennreal[simp]: "0 \<le> x \<Longrightarrow> enn2ereal (ennreal x) = x"
```
```   889   by transfer (simp add: max_absorb2)
```
```   890
```
```   891 lemma e2ennreal_enn2ereal[simp]: "e2ennreal (enn2ereal x) = x"
```
```   892   by (simp add: e2ennreal_def max_absorb2 ennreal.enn2ereal_inverse)
```
```   893
```
```   894 lemma enn2ereal_e2ennreal: "x \<ge> 0 \<Longrightarrow> enn2ereal (e2ennreal x) = x"
```
```   895 by (metis e2ennreal_enn2ereal ereal_ennreal_cases not_le)
```
```   896
```
```   897 lemma e2ennreal_ereal [simp]: "e2ennreal (ereal x) = ennreal x"
```
```   898 by (metis e2ennreal_def enn2ereal_inverse ennreal.rep_eq sup_ereal_def)
```
```   899
```
```   900 lemma ennreal_0[simp]: "ennreal 0 = 0"
```
```   901   by (simp add: ennreal_def max.absorb1 zero_ennreal.abs_eq)
```
```   902
```
```   903 lemma ennreal_1[simp]: "ennreal 1 = 1"
```
```   904   by transfer (simp add: max_absorb2)
```
```   905
```
```   906 lemma ennreal_eq_0_iff: "ennreal x = 0 \<longleftrightarrow> x \<le> 0"
```
```   907   by (cases "0 \<le> x") (auto simp: ennreal_neg)
```
```   908
```
```   909 lemma ennreal_le_iff2: "ennreal x \<le> ennreal y \<longleftrightarrow> ((0 \<le> y \<and> x \<le> y) \<or> (x \<le> 0 \<and> y \<le> 0))"
```
```   910   by (cases "0 \<le> y") (auto simp: ennreal_eq_0_iff ennreal_neg)
```
```   911
```
```   912 lemma ennreal_eq_1[simp]: "ennreal x = 1 \<longleftrightarrow> x = 1"
```
```   913   by (cases "0 \<le> x") (auto simp: ennreal_neg simp flip: ennreal_1)
```
```   914
```
```   915 lemma ennreal_le_1[simp]: "ennreal x \<le> 1 \<longleftrightarrow> x \<le> 1"
```
```   916   by (cases "0 \<le> x") (auto simp: ennreal_neg simp flip: ennreal_1)
```
```   917
```
```   918 lemma ennreal_ge_1[simp]: "ennreal x \<ge> 1 \<longleftrightarrow> x \<ge> 1"
```
```   919   by (cases "0 \<le> x") (auto simp: ennreal_neg simp flip: ennreal_1)
```
```   920
```
```   921 lemma one_less_ennreal[simp]: "1 < ennreal x \<longleftrightarrow> 1 < x"
```
```   922   by transfer (auto simp: max.absorb2 less_max_iff_disj)
```
```   923
```
```   924 lemma ennreal_plus[simp]:
```
```   925   "0 \<le> a \<Longrightarrow> 0 \<le> b \<Longrightarrow> ennreal (a + b) = ennreal a + ennreal b"
```
```   926   by (transfer fixing: a b) (auto simp: max_absorb2)
```
```   927
```
```   928 lemma sum_ennreal[simp]: "(\<And>i. i \<in> I \<Longrightarrow> 0 \<le> f i) \<Longrightarrow> (\<Sum>i\<in>I. ennreal (f i)) = ennreal (sum f I)"
```
```   929   by (induction I rule: infinite_finite_induct) (auto simp: sum_nonneg)
```
```   930
```
```   931 lemma sum_list_ennreal[simp]:
```
```   932   assumes "\<And>x. x \<in> set xs \<Longrightarrow> f x \<ge> 0"
```
```   933   shows   "sum_list (map (\<lambda>x. ennreal (f x)) xs) = ennreal (sum_list (map f xs))"
```
```   934 using assms
```
```   935 proof (induction xs)
```
```   936   case (Cons x xs)
```
```   937   from Cons have "(\<Sum>x\<leftarrow>x # xs. ennreal (f x)) = ennreal (f x) + ennreal (sum_list (map f xs))"
```
```   938     by simp
```
```   939   also from Cons.prems have "\<dots> = ennreal (f x + sum_list (map f xs))"
```
```   940     by (intro ennreal_plus [symmetric] sum_list_nonneg) auto
```
```   941   finally show ?case by simp
```
```   942 qed simp_all
```
```   943
```
```   944 lemma ennreal_of_nat_eq_real_of_nat: "of_nat i = ennreal (of_nat i)"
```
```   945   by (induction i) simp_all
```
```   946
```
```   947 lemma of_nat_le_ennreal_iff[simp]: "0 \<le> r \<Longrightarrow> of_nat i \<le> ennreal r \<longleftrightarrow> of_nat i \<le> r"
```
```   948   by (simp add: ennreal_of_nat_eq_real_of_nat)
```
```   949
```
```   950 lemma ennreal_le_of_nat_iff[simp]: "ennreal r \<le> of_nat i \<longleftrightarrow> r \<le> of_nat i"
```
```   951   by (simp add: ennreal_of_nat_eq_real_of_nat)
```
```   952
```
```   953 lemma ennreal_indicator: "ennreal (indicator A x) = indicator A x"
```
```   954   by (auto split: split_indicator)
```
```   955
```
```   956 lemma ennreal_numeral[simp]: "ennreal (numeral n) = numeral n"
```
```   957   using ennreal_of_nat_eq_real_of_nat[of "numeral n"] by simp
```
```   958
```
```   959 lemma min_ennreal: "0 \<le> x \<Longrightarrow> 0 \<le> y \<Longrightarrow> min (ennreal x) (ennreal y) = ennreal (min x y)"
```
```   960   by (auto split: split_min)
```
```   961
```
```   962 lemma ennreal_half[simp]: "ennreal (1/2) = inverse 2"
```
```   963   by transfer (simp add: max.absorb2)
```
```   964
```
```   965 lemma ennreal_minus: "0 \<le> q \<Longrightarrow> ennreal r - ennreal q = ennreal (r - q)"
```
```   966   by transfer
```
```   967      (simp add: max.absorb2 zero_ereal_def flip: ereal_max)
```
```   968
```
```   969 lemma ennreal_minus_top[simp]: "ennreal a - top = 0"
```
```   970   by (simp add: minus_top_ennreal)
```
```   971
```
```   972 lemma e2eenreal_enn2ereal_diff [simp]:
```
```   973   "e2ennreal(enn2ereal x - enn2ereal y) = x - y" for x y
```
```   974 by (cases x, cases y, auto simp add: ennreal_minus e2ennreal_neg)
```
```   975
```
```   976 lemma ennreal_mult: "0 \<le> a \<Longrightarrow> 0 \<le> b \<Longrightarrow> ennreal (a * b) = ennreal a * ennreal b"
```
```   977   by transfer (simp add: max_absorb2)
```
```   978
```
```   979 lemma ennreal_mult': "0 \<le> a \<Longrightarrow> ennreal (a * b) = ennreal a * ennreal b"
```
```   980   by (cases "0 \<le> b") (auto simp: ennreal_mult ennreal_neg mult_nonneg_nonpos)
```
```   981
```
```   982 lemma indicator_mult_ennreal: "indicator A x * ennreal r = ennreal (indicator A x * r)"
```
```   983   by (simp split: split_indicator)
```
```   984
```
```   985 lemma ennreal_mult'': "0 \<le> b \<Longrightarrow> ennreal (a * b) = ennreal a * ennreal b"
```
```   986   by (cases "0 \<le> a") (auto simp: ennreal_mult ennreal_neg mult_nonpos_nonneg)
```
```   987
```
```   988 lemma numeral_mult_ennreal: "0 \<le> x \<Longrightarrow> numeral b * ennreal x = ennreal (numeral b * x)"
```
```   989   by (simp add: ennreal_mult)
```
```   990
```
```   991 lemma ennreal_power: "0 \<le> r \<Longrightarrow> ennreal r ^ n = ennreal (r ^ n)"
```
```   992   by (induction n) (auto simp: ennreal_mult)
```
```   993
```
```   994 lemma power_eq_top_ennreal: "x ^ n = top \<longleftrightarrow> (n \<noteq> 0 \<and> (x::ennreal) = top)"
```
```   995   by (cases x rule: ennreal_cases)
```
```   996      (auto simp: ennreal_power top_power_ennreal)
```
```   997
```
```   998 lemma inverse_ennreal: "0 < r \<Longrightarrow> inverse (ennreal r) = ennreal (inverse r)"
```
```   999   by transfer (simp add: max.absorb2)
```
```  1000
```
```  1001 lemma divide_ennreal: "0 \<le> r \<Longrightarrow> 0 < q \<Longrightarrow> ennreal r / ennreal q = ennreal (r / q)"
```
```  1002   by (simp add: divide_ennreal_def inverse_ennreal ennreal_mult[symmetric] inverse_eq_divide)
```
```  1003
```
```  1004 lemma ennreal_inverse_power: "inverse (x ^ n :: ennreal) = inverse x ^ n"
```
```  1005 proof (cases x rule: ennreal_cases)
```
```  1006   case top with power_eq_top_ennreal[of x n] show ?thesis
```
```  1007     by (cases "n = 0") auto
```
```  1008 next
```
```  1009   case (real r) then show ?thesis
```
```  1010   proof cases
```
```  1011     assume "x = 0" then show ?thesis
```
```  1012       using power_eq_top_ennreal[of top "n - 1"]
```
```  1013       by (cases n) (auto simp: ennreal_top_mult)
```
```  1014   next
```
```  1015     assume "x \<noteq> 0"
```
```  1016     with real have "0 < r" by auto
```
```  1017     with real show ?thesis
```
```  1018       by (induction n)
```
```  1019          (auto simp add: ennreal_power ennreal_mult[symmetric] inverse_ennreal)
```
```  1020   qed
```
```  1021 qed
```
```  1022
```
```  1023 lemma ennreal_divide_numeral: "0 \<le> x \<Longrightarrow> ennreal x / numeral b = ennreal (x / numeral b)"
```
```  1024   by (subst divide_ennreal[symmetric]) auto
```
```  1025
```
```  1026 lemma prod_ennreal: "(\<And>i. i \<in> A \<Longrightarrow> 0 \<le> f i) \<Longrightarrow> (\<Prod>i\<in>A. ennreal (f i)) = ennreal (prod f A)"
```
```  1027   by (induction A rule: infinite_finite_induct)
```
```  1028      (auto simp: ennreal_mult prod_nonneg)
```
```  1029
```
```  1030 lemma mult_right_ennreal_cancel: "a * ennreal c = b * ennreal c \<longleftrightarrow> (a = b \<or> c \<le> 0)"
```
```  1031   apply (cases "0 \<le> c")
```
```  1032   apply (cases a b rule: ennreal2_cases)
```
```  1033   apply (auto simp: ennreal_mult[symmetric] ennreal_neg ennreal_top_mult)
```
```  1034   done
```
```  1035
```
```  1036 lemma ennreal_le_epsilon:
```
```  1037   "(\<And>e::real. y < top \<Longrightarrow> 0 < e \<Longrightarrow> x \<le> y + ennreal e) \<Longrightarrow> x \<le> y"
```
```  1038   apply (cases y rule: ennreal_cases)
```
```  1039   apply (cases x rule: ennreal_cases)
```
```  1040   apply (auto simp flip: ennreal_plus simp add: top_unique intro: zero_less_one field_le_epsilon)
```
```  1041   done
```
```  1042
```
```  1043 lemma ennreal_rat_dense:
```
```  1044   fixes x y :: ennreal
```
```  1045   shows "x < y \<Longrightarrow> \<exists>r::rat. x < real_of_rat r \<and> real_of_rat r < y"
```
```  1046 proof transfer
```
```  1047   fix x y :: ereal assume xy: "0 \<le> x" "0 \<le> y" "x < y"
```
```  1048   moreover
```
```  1049   from ereal_dense3[OF \<open>x < y\<close>]
```
```  1050   obtain r where r: "x < ereal (real_of_rat r)" "ereal (real_of_rat r) < y"
```
```  1051     by auto
```
```  1052   then have "0 \<le> r"
```
```  1053     using le_less_trans[OF \<open>0 \<le> x\<close> \<open>x < ereal (real_of_rat r)\<close>] by auto
```
```  1054   with r show "\<exists>r. x < (sup 0 \<circ> ereal) (real_of_rat r) \<and> (sup 0 \<circ> ereal) (real_of_rat r) < y"
```
```  1055     by (intro exI[of _ r]) (auto simp: max_absorb2)
```
```  1056 qed
```
```  1057
```
```  1058 lemma ennreal_Ex_less_of_nat: "(x::ennreal) < top \<Longrightarrow> \<exists>n. x < of_nat n"
```
```  1059   by (cases x rule: ennreal_cases)
```
```  1060      (auto simp: ennreal_of_nat_eq_real_of_nat ennreal_less_iff reals_Archimedean2)
```
```  1061
```
```  1062 subsection \<open>Coercion from \<^typ>\<open>ennreal\<close> to \<^typ>\<open>real\<close>\<close>
```
```  1063
```
```  1064 definition "enn2real x = real_of_ereal (enn2ereal x)"
```
```  1065
```
```  1066 lemma enn2real_nonneg[simp]: "0 \<le> enn2real x"
```
```  1067   by (auto simp: enn2real_def intro!: real_of_ereal_pos enn2ereal_nonneg)
```
```  1068
```
```  1069 lemma enn2real_mono: "a \<le> b \<Longrightarrow> b < top \<Longrightarrow> enn2real a \<le> enn2real b"
```
```  1070   by (auto simp add: enn2real_def less_eq_ennreal.rep_eq intro!: real_of_ereal_positive_mono enn2ereal_nonneg)
```
```  1071
```
```  1072 lemma enn2real_of_nat[simp]: "enn2real (of_nat n) = n"
```
```  1073   by (auto simp: enn2real_def)
```
```  1074
```
```  1075 lemma enn2real_ennreal[simp]: "0 \<le> r \<Longrightarrow> enn2real (ennreal r) = r"
```
```  1076   by (simp add: enn2real_def)
```
```  1077
```
```  1078 lemma ennreal_enn2real[simp]: "r < top \<Longrightarrow> ennreal (enn2real r) = r"
```
```  1079   by (cases r rule: ennreal_cases) auto
```
```  1080
```
```  1081 lemma real_of_ereal_enn2ereal[simp]: "real_of_ereal (enn2ereal x) = enn2real x"
```
```  1082   by (simp add: enn2real_def)
```
```  1083
```
```  1084 lemma enn2real_top[simp]: "enn2real top = 0"
```
```  1085   unfolding enn2real_def top_ennreal.rep_eq top_ereal_def by simp
```
```  1086
```
```  1087 lemma enn2real_0[simp]: "enn2real 0 = 0"
```
```  1088   unfolding enn2real_def zero_ennreal.rep_eq by simp
```
```  1089
```
```  1090 lemma enn2real_1[simp]: "enn2real 1 = 1"
```
```  1091   unfolding enn2real_def one_ennreal.rep_eq by simp
```
```  1092
```
```  1093 lemma enn2real_numeral[simp]: "enn2real (numeral n) = (numeral n)"
```
```  1094   unfolding enn2real_def by simp
```
```  1095
```
```  1096 lemma enn2real_mult: "enn2real (a * b) = enn2real a * enn2real b"
```
```  1097   unfolding enn2real_def
```
```  1098   by (simp del: real_of_ereal_enn2ereal add: times_ennreal.rep_eq)
```
```  1099
```
```  1100 lemma enn2real_leI: "0 \<le> B \<Longrightarrow> x \<le> ennreal B \<Longrightarrow> enn2real x \<le> B"
```
```  1101   by (cases x rule: ennreal_cases) (auto simp: top_unique)
```
```  1102
```
```  1103 lemma enn2real_positive_iff: "0 < enn2real x \<longleftrightarrow> (0 < x \<and> x < top)"
```
```  1104   by (cases x rule: ennreal_cases) auto
```
```  1105
```
```  1106 lemma enn2real_eq_1_iff[simp]: "enn2real x = 1 \<longleftrightarrow> x = 1"
```
```  1107   by (cases x) auto
```
```  1108
```
```  1109 subsection \<open>Coercion from \<^typ>\<open>enat\<close> to \<^typ>\<open>ennreal\<close>\<close>
```
```  1110
```
```  1111
```
```  1112 definition ennreal_of_enat :: "enat \<Rightarrow> ennreal"
```
```  1113 where
```
```  1114   "ennreal_of_enat n = (case n of \<infinity> \<Rightarrow> top | enat n \<Rightarrow> of_nat n)"
```
```  1115
```
```  1116 declare [[coercion ennreal_of_enat]]
```
```  1117 declare [[coercion "of_nat :: nat \<Rightarrow> ennreal"]]
```
```  1118
```
```  1119 lemma ennreal_of_enat_infty[simp]: "ennreal_of_enat \<infinity> = \<infinity>"
```
```  1120   by (simp add: ennreal_of_enat_def)
```
```  1121
```
```  1122 lemma ennreal_of_enat_enat[simp]: "ennreal_of_enat (enat n) = of_nat n"
```
```  1123   by (simp add: ennreal_of_enat_def)
```
```  1124
```
```  1125 lemma ennreal_of_enat_0[simp]: "ennreal_of_enat 0 = 0"
```
```  1126   using ennreal_of_enat_enat[of 0] unfolding enat_0 by simp
```
```  1127
```
```  1128 lemma ennreal_of_enat_1[simp]: "ennreal_of_enat 1 = 1"
```
```  1129   using ennreal_of_enat_enat[of 1] unfolding enat_1 by simp
```
```  1130
```
```  1131 lemma ennreal_top_neq_of_nat[simp]: "(top::ennreal) \<noteq> of_nat i"
```
```  1132   using ennreal_of_nat_neq_top[of i] by metis
```
```  1133
```
```  1134 lemma ennreal_of_enat_inj[simp]: "ennreal_of_enat i = ennreal_of_enat j \<longleftrightarrow> i = j"
```
```  1135   by (cases i j rule: enat.exhaust[case_product enat.exhaust]) auto
```
```  1136
```
```  1137 lemma ennreal_of_enat_le_iff[simp]: "ennreal_of_enat m \<le> ennreal_of_enat n \<longleftrightarrow> m \<le> n"
```
```  1138   by (auto simp: ennreal_of_enat_def top_unique split: enat.split)
```
```  1139
```
```  1140 lemma of_nat_less_ennreal_of_nat[simp]: "of_nat n \<le> ennreal_of_enat x \<longleftrightarrow> of_nat n \<le> x"
```
```  1141   by (cases x) (auto simp: of_nat_eq_enat)
```
```  1142
```
```  1143 lemma ennreal_of_enat_Sup: "ennreal_of_enat (Sup X) = (SUP x\<in>X. ennreal_of_enat x)"
```
```  1144 proof -
```
```  1145   have "ennreal_of_enat (Sup X) \<le> (SUP x \<in> X. ennreal_of_enat x)"
```
```  1146     unfolding Sup_enat_def
```
```  1147   proof (clarsimp, intro conjI impI)
```
```  1148     fix x assume "finite X" "X \<noteq> {}"
```
```  1149     then show "ennreal_of_enat (Max X) \<le> (SUP x \<in> X. ennreal_of_enat x)"
```
```  1150       by (intro SUP_upper Max_in)
```
```  1151   next
```
```  1152     assume "infinite X" "X \<noteq> {}"
```
```  1153     have "\<exists>y\<in>X. r < ennreal_of_enat y" if r: "r < top" for r
```
```  1154     proof -
```
```  1155       from ennreal_Ex_less_of_nat[OF r] guess n .. note n = this
```
```  1156       have "\<not> (X \<subseteq> enat ` {.. n})"
```
```  1157         using \<open>infinite X\<close> by (auto dest: finite_subset)
```
```  1158       then obtain x where x: "x \<in> X" "x \<notin> enat ` {..n}"
```
```  1159         by blast
```
```  1160       then have "of_nat n \<le> x"
```
```  1161         by (cases x) (auto simp: of_nat_eq_enat)
```
```  1162       with x show ?thesis
```
```  1163         by (auto intro!: bexI[of _ x] less_le_trans[OF n])
```
```  1164     qed
```
```  1165     then have "(SUP x \<in> X. ennreal_of_enat x) = top"
```
```  1166       by simp
```
```  1167     then show "top \<le> (SUP x \<in> X. ennreal_of_enat x)"
```
```  1168       unfolding top_unique by simp
```
```  1169   qed
```
```  1170   then show ?thesis
```
```  1171     by (auto intro!: antisym Sup_least intro: Sup_upper)
```
```  1172 qed
```
```  1173
```
```  1174 lemma ennreal_of_enat_eSuc[simp]: "ennreal_of_enat (eSuc x) = 1 + ennreal_of_enat x"
```
```  1175   by (cases x) (auto simp: eSuc_enat)
```
```  1176
```
```  1177 subsection \<open>Topology on \<^typ>\<open>ennreal\<close>\<close>
```
```  1178
```
```  1179 lemma enn2ereal_Iio: "enn2ereal -` {..<a} = (if 0 \<le> a then {..< e2ennreal a} else {})"
```
```  1180   using enn2ereal_nonneg
```
```  1181   by (cases a rule: ereal_ennreal_cases)
```
```  1182      (auto simp add: vimage_def set_eq_iff ennreal.enn2ereal_inverse less_ennreal.rep_eq e2ennreal_def max_absorb2
```
```  1183            simp del: enn2ereal_nonneg
```
```  1184            intro: le_less_trans less_imp_le)
```
```  1185
```
```  1186 lemma enn2ereal_Ioi: "enn2ereal -` {a <..} = (if 0 \<le> a then {e2ennreal a <..} else UNIV)"
```
```  1187   by (cases a rule: ereal_ennreal_cases)
```
```  1188      (auto simp add: vimage_def set_eq_iff ennreal.enn2ereal_inverse less_ennreal.rep_eq e2ennreal_def max_absorb2
```
```  1189            intro: less_le_trans)
```
```  1190
```
```  1191 instantiation ennreal :: linear_continuum_topology
```
```  1192 begin
```
```  1193
```
```  1194 definition open_ennreal :: "ennreal set \<Rightarrow> bool"
```
```  1195   where "(open :: ennreal set \<Rightarrow> bool) = generate_topology (range lessThan \<union> range greaterThan)"
```
```  1196
```
```  1197 instance
```
```  1198 proof
```
```  1199   show "\<exists>a b::ennreal. a \<noteq> b"
```
```  1200     using zero_neq_one by (intro exI)
```
```  1201   show "\<And>x y::ennreal. x < y \<Longrightarrow> \<exists>z>x. z < y"
```
```  1202   proof transfer
```
```  1203     fix x y :: ereal assume "0 \<le> x" and *: "x < y"
```
```  1204     moreover from dense[OF *] guess z ..
```
```  1205     ultimately show "\<exists>z\<in>Collect ((\<le>) 0). x < z \<and> z < y"
```
```  1206       by (intro bexI[of _ z]) auto
```
```  1207   qed
```
```  1208 qed (rule open_ennreal_def)
```
```  1209
```
```  1210 end
```
```  1211
```
```  1212 lemma continuous_on_e2ennreal: "continuous_on A e2ennreal"
```
```  1213 proof (rule continuous_on_subset)
```
```  1214   show "continuous_on ({0..} \<union> {..0}) e2ennreal"
```
```  1215   proof (rule continuous_on_closed_Un)
```
```  1216     show "continuous_on {0 ..} e2ennreal"
```
```  1217       by (rule continuous_onI_mono)
```
```  1218          (auto simp add: less_eq_ennreal.abs_eq eq_onp_def enn2ereal_range)
```
```  1219     show "continuous_on {.. 0} e2ennreal"
```
```  1220       by (subst continuous_on_cong[OF refl, of _ _ "\<lambda>_. 0"])
```
```  1221          (auto simp add: e2ennreal_neg continuous_on_const)
```
```  1222   qed auto
```
```  1223   show "A \<subseteq> {0..} \<union> {..0::ereal}"
```
```  1224     by auto
```
```  1225 qed
```
```  1226
```
```  1227 lemma continuous_at_e2ennreal: "continuous (at x within A) e2ennreal"
```
```  1228   by (rule continuous_on_imp_continuous_within[OF continuous_on_e2ennreal, of _ UNIV]) auto
```
```  1229
```
```  1230 lemma continuous_on_enn2ereal: "continuous_on UNIV enn2ereal"
```
```  1231   by (rule continuous_on_generate_topology[OF open_generated_order])
```
```  1232      (auto simp add: enn2ereal_Iio enn2ereal_Ioi)
```
```  1233
```
```  1234 lemma continuous_at_enn2ereal: "continuous (at x within A) enn2ereal"
```
```  1235   by (rule continuous_on_imp_continuous_within[OF continuous_on_enn2ereal]) auto
```
```  1236
```
```  1237 lemma sup_continuous_e2ennreal[order_continuous_intros]:
```
```  1238   assumes f: "sup_continuous f" shows "sup_continuous (\<lambda>x. e2ennreal (f x))"
```
```  1239   apply (rule sup_continuous_compose[OF _ f])
```
```  1240   apply (rule continuous_at_left_imp_sup_continuous)
```
```  1241   apply (auto simp: mono_def e2ennreal_mono continuous_at_e2ennreal)
```
```  1242   done
```
```  1243
```
```  1244 lemma sup_continuous_enn2ereal[order_continuous_intros]:
```
```  1245   assumes f: "sup_continuous f" shows "sup_continuous (\<lambda>x. enn2ereal (f x))"
```
```  1246   apply (rule sup_continuous_compose[OF _ f])
```
```  1247   apply (rule continuous_at_left_imp_sup_continuous)
```
```  1248   apply (simp_all add: mono_def less_eq_ennreal.rep_eq continuous_at_enn2ereal)
```
```  1249   done
```
```  1250
```
```  1251 lemma sup_continuous_mult_left_ennreal':
```
```  1252   fixes c :: "ennreal"
```
```  1253   shows "sup_continuous (\<lambda>x. c * x)"
```
```  1254   unfolding sup_continuous_def
```
```  1255   by transfer (auto simp: SUP_ereal_mult_left max.absorb2 SUP_upper2)
```
```  1256
```
```  1257 lemma sup_continuous_mult_left_ennreal[order_continuous_intros]:
```
```  1258   "sup_continuous f \<Longrightarrow> sup_continuous (\<lambda>x. c * f x :: ennreal)"
```
```  1259   by (rule sup_continuous_compose[OF sup_continuous_mult_left_ennreal'])
```
```  1260
```
```  1261 lemma sup_continuous_mult_right_ennreal[order_continuous_intros]:
```
```  1262   "sup_continuous f \<Longrightarrow> sup_continuous (\<lambda>x. f x * c :: ennreal)"
```
```  1263   using sup_continuous_mult_left_ennreal[of f c] by (simp add: mult.commute)
```
```  1264
```
```  1265 lemma sup_continuous_divide_ennreal[order_continuous_intros]:
```
```  1266   fixes f g :: "'a::complete_lattice \<Rightarrow> ennreal"
```
```  1267   shows "sup_continuous f \<Longrightarrow> sup_continuous (\<lambda>x. f x / c)"
```
```  1268   unfolding divide_ennreal_def by (rule sup_continuous_mult_right_ennreal)
```
```  1269
```
```  1270 lemma transfer_enn2ereal_continuous_on [transfer_rule]:
```
```  1271   "rel_fun (=) (rel_fun (rel_fun (=) pcr_ennreal) (=)) continuous_on continuous_on"
```
```  1272 proof -
```
```  1273   have "continuous_on A f" if "continuous_on A (\<lambda>x. enn2ereal (f x))" for A and f :: "'a \<Rightarrow> ennreal"
```
```  1274     using continuous_on_compose2[OF continuous_on_e2ennreal[of "{0..}"] that]
```
```  1275     by (auto simp: ennreal.enn2ereal_inverse subset_eq e2ennreal_def max_absorb2)
```
```  1276   moreover
```
```  1277   have "continuous_on A (\<lambda>x. enn2ereal (f x))" if "continuous_on A f" for A and f :: "'a \<Rightarrow> ennreal"
```
```  1278     using continuous_on_compose2[OF continuous_on_enn2ereal that] by auto
```
```  1279   ultimately
```
```  1280   show ?thesis
```
```  1281     by (auto simp add: rel_fun_def ennreal.pcr_cr_eq cr_ennreal_def)
```
```  1282 qed
```
```  1283
```
```  1284 lemma transfer_sup_continuous[transfer_rule]:
```
```  1285   "(rel_fun (rel_fun (=) pcr_ennreal) (=)) sup_continuous sup_continuous"
```
```  1286 proof (safe intro!: rel_funI dest!: rel_fun_eq_pcr_ennreal[THEN iffD1])
```
```  1287   show "sup_continuous (enn2ereal \<circ> f) \<Longrightarrow> sup_continuous f" for f :: "'a \<Rightarrow> _"
```
```  1288     using sup_continuous_e2ennreal[of "enn2ereal \<circ> f"] by simp
```
```  1289   show "sup_continuous f \<Longrightarrow> sup_continuous (enn2ereal \<circ> f)" for f :: "'a \<Rightarrow> _"
```
```  1290     using sup_continuous_enn2ereal[of f] by (simp add: comp_def)
```
```  1291 qed
```
```  1292
```
```  1293 lemma continuous_on_ennreal[tendsto_intros]:
```
```  1294   "continuous_on A f \<Longrightarrow> continuous_on A (\<lambda>x. ennreal (f x))"
```
```  1295   by transfer (auto intro!: continuous_on_max continuous_on_const continuous_on_ereal)
```
```  1296
```
```  1297 lemma tendsto_ennrealD:
```
```  1298   assumes lim: "((\<lambda>x. ennreal (f x)) \<longlongrightarrow> ennreal x) F"
```
```  1299   assumes *: "\<forall>\<^sub>F x in F. 0 \<le> f x" and x: "0 \<le> x"
```
```  1300   shows "(f \<longlongrightarrow> x) F"
```
```  1301   using continuous_on_tendsto_compose[OF continuous_on_enn2ereal lim]
```
```  1302   apply simp
```
```  1303   apply (subst (asm) tendsto_cong)
```
```  1304   using *
```
```  1305   apply eventually_elim
```
```  1306   apply (auto simp: max_absorb2 \<open>0 \<le> x\<close>)
```
```  1307   done
```
```  1308
```
```  1309 lemma tendsto_ennreal_iff[simp]:
```
```  1310   "\<forall>\<^sub>F x in F. 0 \<le> f x \<Longrightarrow> 0 \<le> x \<Longrightarrow> ((\<lambda>x. ennreal (f x)) \<longlongrightarrow> ennreal x) F \<longleftrightarrow> (f \<longlongrightarrow> x) F"
```
```  1311   by (auto dest: tendsto_ennrealD)
```
```  1312      (auto simp: ennreal_def
```
```  1313            intro!: continuous_on_tendsto_compose[OF continuous_on_e2ennreal[of UNIV]] tendsto_max)
```
```  1314
```
```  1315 lemma tendsto_enn2ereal_iff[simp]: "((\<lambda>i. enn2ereal (f i)) \<longlongrightarrow> enn2ereal x) F \<longleftrightarrow> (f \<longlongrightarrow> x) F"
```
```  1316   using continuous_on_enn2ereal[THEN continuous_on_tendsto_compose, of f x F]
```
```  1317     continuous_on_e2ennreal[THEN continuous_on_tendsto_compose, of "\<lambda>x. enn2ereal (f x)" "enn2ereal x" F UNIV]
```
```  1318   by auto
```
```  1319
```
```  1320 lemma continuous_on_add_ennreal:
```
```  1321   fixes f g :: "'a::topological_space \<Rightarrow> ennreal"
```
```  1322   shows "continuous_on A f \<Longrightarrow> continuous_on A g \<Longrightarrow> continuous_on A (\<lambda>x. f x + g x)"
```
```  1323   by (transfer fixing: A) (auto intro!: tendsto_add_ereal_nonneg simp: continuous_on_def)
```
```  1324
```
```  1325 lemma continuous_on_inverse_ennreal[continuous_intros]:
```
```  1326   fixes f :: "'a::topological_space \<Rightarrow> ennreal"
```
```  1327   shows "continuous_on A f \<Longrightarrow> continuous_on A (\<lambda>x. inverse (f x))"
```
```  1328 proof (transfer fixing: A)
```
```  1329   show "pred_fun top  ((\<le>) 0) f \<Longrightarrow> continuous_on A (\<lambda>x. inverse (f x))" if "continuous_on A f"
```
```  1330     for f :: "'a \<Rightarrow> ereal"
```
```  1331     using continuous_on_compose2[OF continuous_on_inverse_ereal that] by (auto simp: subset_eq)
```
```  1332 qed
```
```  1333
```
```  1334 instance ennreal :: topological_comm_monoid_add
```
```  1335 proof
```
```  1336   show "((\<lambda>x. fst x + snd x) \<longlongrightarrow> a + b) (nhds a \<times>\<^sub>F nhds b)" for a b :: ennreal
```
```  1337     using continuous_on_add_ennreal[of UNIV fst snd]
```
```  1338     using tendsto_at_iff_tendsto_nhds[symmetric, of "\<lambda>x::(ennreal \<times> ennreal). fst x + snd x"]
```
```  1339     by (auto simp: continuous_on_eq_continuous_at)
```
```  1340        (simp add: isCont_def nhds_prod[symmetric])
```
```  1341 qed
```
```  1342
```
```  1343 lemma sup_continuous_add_ennreal[order_continuous_intros]:
```
```  1344   fixes f g :: "'a::complete_lattice \<Rightarrow> ennreal"
```
```  1345   shows "sup_continuous f \<Longrightarrow> sup_continuous g \<Longrightarrow> sup_continuous (\<lambda>x. f x + g x)"
```
```  1346   by transfer (auto intro!: sup_continuous_add)
```
```  1347
```
```  1348 lemma ennreal_suminf_lessD: "(\<Sum>i. f i :: ennreal) < x \<Longrightarrow> f i < x"
```
```  1349   using le_less_trans[OF sum_le_suminf[OF summableI, of "{i}" f]] by simp
```
```  1350
```
```  1351 lemma sums_ennreal[simp]: "(\<And>i. 0 \<le> f i) \<Longrightarrow> 0 \<le> x \<Longrightarrow> (\<lambda>i. ennreal (f i)) sums ennreal x \<longleftrightarrow> f sums x"
```
```  1352   unfolding sums_def by (simp add: always_eventually sum_nonneg)
```
```  1353
```
```  1354 lemma summable_suminf_not_top: "(\<And>i. 0 \<le> f i) \<Longrightarrow> (\<Sum>i. ennreal (f i)) \<noteq> top \<Longrightarrow> summable f"
```
```  1355   using summable_sums[OF summableI, of "\<lambda>i. ennreal (f i)"]
```
```  1356   by (cases "\<Sum>i. ennreal (f i)" rule: ennreal_cases)
```
```  1357      (auto simp: summable_def)
```
```  1358
```
```  1359 lemma suminf_ennreal[simp]:
```
```  1360   "(\<And>i. 0 \<le> f i) \<Longrightarrow> (\<Sum>i. ennreal (f i)) \<noteq> top \<Longrightarrow> (\<Sum>i. ennreal (f i)) = ennreal (\<Sum>i. f i)"
```
```  1361   by (rule sums_unique[symmetric]) (simp add: summable_suminf_not_top suminf_nonneg summable_sums)
```
```  1362
```
```  1363 lemma sums_enn2ereal[simp]: "(\<lambda>i. enn2ereal (f i)) sums enn2ereal x \<longleftrightarrow> f sums x"
```
```  1364   unfolding sums_def by (simp add: always_eventually sum_nonneg)
```
```  1365
```
```  1366 lemma suminf_enn2ereal[simp]: "(\<Sum>i. enn2ereal (f i)) = enn2ereal (suminf f)"
```
```  1367   by (rule sums_unique[symmetric]) (simp add: summable_sums)
```
```  1368
```
```  1369 lemma transfer_e2ennreal_suminf [transfer_rule]: "rel_fun (rel_fun (=) pcr_ennreal) pcr_ennreal suminf suminf"
```
```  1370   by (auto simp: rel_funI rel_fun_eq_pcr_ennreal comp_def)
```
```  1371
```
```  1372 lemma ennreal_suminf_cmult[simp]: "(\<Sum>i. r * f i) = r * (\<Sum>i. f i::ennreal)"
```
```  1373   by transfer (auto intro!: suminf_cmult_ereal)
```
```  1374
```
```  1375 lemma ennreal_suminf_multc[simp]: "(\<Sum>i. f i * r) = (\<Sum>i. f i::ennreal) * r"
```
```  1376   using ennreal_suminf_cmult[of r f] by (simp add: ac_simps)
```
```  1377
```
```  1378 lemma ennreal_suminf_divide[simp]: "(\<Sum>i. f i / r) = (\<Sum>i. f i::ennreal) / r"
```
```  1379   by (simp add: divide_ennreal_def)
```
```  1380
```
```  1381 lemma ennreal_suminf_neq_top: "summable f \<Longrightarrow> (\<And>i. 0 \<le> f i) \<Longrightarrow> (\<Sum>i. ennreal (f i)) \<noteq> top"
```
```  1382   using sums_ennreal[of f "suminf f"]
```
```  1383   by (simp add: suminf_nonneg flip: sums_unique summable_sums_iff del: sums_ennreal)
```
```  1384
```
```  1385 lemma suminf_ennreal_eq:
```
```  1386   "(\<And>i. 0 \<le> f i) \<Longrightarrow> f sums x \<Longrightarrow> (\<Sum>i. ennreal (f i)) = ennreal x"
```
```  1387   using suminf_nonneg[of f] sums_unique[of f x]
```
```  1388   by (intro sums_unique[symmetric]) (auto simp: summable_sums_iff)
```
```  1389
```
```  1390 lemma ennreal_suminf_bound_add:
```
```  1391   fixes f :: "nat \<Rightarrow> ennreal"
```
```  1392   shows "(\<And>N. (\<Sum>n<N. f n) + y \<le> x) \<Longrightarrow> suminf f + y \<le> x"
```
```  1393   by transfer (auto intro!: suminf_bound_add)
```
```  1394
```
```  1395 lemma ennreal_suminf_SUP_eq_directed:
```
```  1396   fixes f :: "'a \<Rightarrow> nat \<Rightarrow> ennreal"
```
```  1397   assumes *: "\<And>N i j. i \<in> I \<Longrightarrow> j \<in> I \<Longrightarrow> finite N \<Longrightarrow> \<exists>k\<in>I. \<forall>n\<in>N. f i n \<le> f k n \<and> f j n \<le> f k n"
```
```  1398   shows "(\<Sum>n. SUP i\<in>I. f i n) = (SUP i\<in>I. \<Sum>n. f i n)"
```
```  1399 proof cases
```
```  1400   assume "I \<noteq> {}"
```
```  1401   then obtain i where "i \<in> I" by auto
```
```  1402   from * show ?thesis
```
```  1403     by (transfer fixing: I)
```
```  1404        (auto simp: max_absorb2 SUP_upper2[OF \<open>i \<in> I\<close>] suminf_nonneg summable_ereal_pos \<open>I \<noteq> {}\<close>
```
```  1405              intro!: suminf_SUP_eq_directed)
```
```  1406 qed (simp add: bot_ennreal)
```
```  1407
```
```  1408 lemma INF_ennreal_add_const:
```
```  1409   fixes f g :: "nat \<Rightarrow> ennreal"
```
```  1410   shows "(INF i. f i + c) = (INF i. f i) + c"
```
```  1411   using continuous_at_Inf_mono[of "\<lambda>x. x + c" "f`UNIV"]
```
```  1412   using continuous_add[of "at_right (Inf (range f))", of "\<lambda>x. x" "\<lambda>x. c"]
```
```  1413   by (auto simp: mono_def image_comp)
```
```  1414
```
```  1415 lemma INF_ennreal_const_add:
```
```  1416   fixes f g :: "nat \<Rightarrow> ennreal"
```
```  1417   shows "(INF i. c + f i) = c + (INF i. f i)"
```
```  1418   using INF_ennreal_add_const[of f c] by (simp add: ac_simps)
```
```  1419
```
```  1420 lemma SUP_mult_left_ennreal: "c * (SUP i\<in>I. f i) = (SUP i\<in>I. c * f i ::ennreal)"
```
```  1421 proof cases
```
```  1422   assume "I \<noteq> {}" then show ?thesis
```
```  1423     by transfer (auto simp add: SUP_ereal_mult_left max_absorb2 SUP_upper2)
```
```  1424 qed (simp add: bot_ennreal)
```
```  1425
```
```  1426 lemma SUP_mult_right_ennreal: "(SUP i\<in>I. f i) * c = (SUP i\<in>I. f i * c ::ennreal)"
```
```  1427   using SUP_mult_left_ennreal by (simp add: mult.commute)
```
```  1428
```
```  1429 lemma SUP_divide_ennreal: "(SUP i\<in>I. f i) / c = (SUP i\<in>I. f i / c ::ennreal)"
```
```  1430   using SUP_mult_right_ennreal by (simp add: divide_ennreal_def)
```
```  1431
```
```  1432 lemma ennreal_SUP_of_nat_eq_top: "(SUP x. of_nat x :: ennreal) = top"
```
```  1433 proof (intro antisym top_greatest le_SUP_iff[THEN iffD2] allI impI)
```
```  1434   fix y :: ennreal assume "y < top"
```
```  1435   then obtain r where "y = ennreal r"
```
```  1436     by (cases y rule: ennreal_cases) auto
```
```  1437   then show "\<exists>i\<in>UNIV. y < of_nat i"
```
```  1438     using reals_Archimedean2[of "max 1 r"] zero_less_one
```
```  1439     by (simp add: ennreal_Ex_less_of_nat)
```
```  1440 qed
```
```  1441
```
```  1442 lemma ennreal_SUP_eq_top:
```
```  1443   fixes f :: "'a \<Rightarrow> ennreal"
```
```  1444   assumes "\<And>n. \<exists>i\<in>I. of_nat n \<le> f i"
```
```  1445   shows "(SUP i \<in> I. f i) = top"
```
```  1446 proof -
```
```  1447   have "(SUP x. of_nat x :: ennreal) \<le> (SUP i \<in> I. f i)"
```
```  1448     using assms by (auto intro!: SUP_least intro: SUP_upper2)
```
```  1449   then show ?thesis
```
```  1450     by (auto simp: ennreal_SUP_of_nat_eq_top top_unique)
```
```  1451 qed
```
```  1452
```
```  1453 lemma ennreal_INF_const_minus:
```
```  1454   fixes f :: "'a \<Rightarrow> ennreal"
```
```  1455   shows "I \<noteq> {} \<Longrightarrow> (SUP x\<in>I. c - f x) = c - (INF x\<in>I. f x)"
```
```  1456   by (transfer fixing: I)
```
```  1457      (simp add: sup_max[symmetric] SUP_sup_const1 SUP_ereal_minus_right del: sup_ereal_def)
```
```  1458
```
```  1459 lemma of_nat_Sup_ennreal:
```
```  1460   assumes "A \<noteq> {}" "bdd_above A"
```
```  1461   shows "of_nat (Sup A) = (SUP a\<in>A. of_nat a :: ennreal)"
```
```  1462 proof (intro antisym)
```
```  1463   show "(SUP a\<in>A. of_nat a::ennreal) \<le> of_nat (Sup A)"
```
```  1464     by (intro SUP_least of_nat_mono) (auto intro: cSup_upper assms)
```
```  1465   have "Sup A \<in> A"
```
```  1466     unfolding Sup_nat_def using assms by (intro Max_in) (auto simp: bdd_above_nat)
```
```  1467   then show "of_nat (Sup A) \<le> (SUP a\<in>A. of_nat a::ennreal)"
```
```  1468     by (intro SUP_upper)
```
```  1469 qed
```
```  1470
```
```  1471 lemma ennreal_tendsto_const_minus:
```
```  1472   fixes g :: "'a \<Rightarrow> ennreal"
```
```  1473   assumes ae: "\<forall>\<^sub>F x in F. g x \<le> c"
```
```  1474   assumes g: "((\<lambda>x. c - g x) \<longlongrightarrow> 0) F"
```
```  1475   shows "(g \<longlongrightarrow> c) F"
```
```  1476 proof (cases c rule: ennreal_cases)
```
```  1477   case top with tendsto_unique[OF _ g, of "top"] show ?thesis
```
```  1478     by (cases "F = bot") auto
```
```  1479 next
```
```  1480   case (real r)
```
```  1481   then have "\<forall>x. \<exists>q\<ge>0. g x \<le> c \<longrightarrow> (g x = ennreal q \<and> q \<le> r)"
```
```  1482     by (auto simp: le_ennreal_iff)
```
```  1483   then obtain f where *: "0 \<le> f x" "g x = ennreal (f x)" "f x \<le> r" if "g x \<le> c" for x
```
```  1484     by metis
```
```  1485   from ae have ae2: "\<forall>\<^sub>F x in F. c - g x = ennreal (r - f x) \<and> f x \<le> r \<and> g x = ennreal (f x) \<and> 0 \<le> f x"
```
```  1486   proof eventually_elim
```
```  1487     fix x assume "g x \<le> c" with *[of x] \<open>0 \<le> r\<close> show "c - g x = ennreal (r - f x) \<and> f x \<le> r \<and> g x = ennreal (f x) \<and> 0 \<le> f x"
```
```  1488       by (auto simp: real ennreal_minus)
```
```  1489   qed
```
```  1490   with g have "((\<lambda>x. ennreal (r - f x)) \<longlongrightarrow> ennreal 0) F"
```
```  1491     by (auto simp add: tendsto_cong eventually_conj_iff)
```
```  1492   with ae2 have "((\<lambda>x. r - f x) \<longlongrightarrow> 0) F"
```
```  1493     by (subst (asm) tendsto_ennreal_iff) (auto elim: eventually_mono)
```
```  1494   then have "(f \<longlongrightarrow> r) F"
```
```  1495     by (rule Lim_transform2[OF tendsto_const])
```
```  1496   with ae2 have "((\<lambda>x. ennreal (f x)) \<longlongrightarrow> ennreal r) F"
```
```  1497     by (subst tendsto_ennreal_iff) (auto elim: eventually_mono simp: real)
```
```  1498   with ae2 show ?thesis
```
```  1499     by (auto simp: real tendsto_cong eventually_conj_iff)
```
```  1500 qed
```
```  1501
```
```  1502 lemma ennreal_SUP_add:
```
```  1503   fixes f g :: "nat \<Rightarrow> ennreal"
```
```  1504   shows "incseq f \<Longrightarrow> incseq g \<Longrightarrow> (SUP i. f i + g i) = Sup (f ` UNIV) + Sup (g ` UNIV)"
```
```  1505   unfolding incseq_def le_fun_def
```
```  1506   by transfer
```
```  1507      (simp add: SUP_ereal_add incseq_def le_fun_def max_absorb2 SUP_upper2)
```
```  1508
```
```  1509 lemma ennreal_SUP_sum:
```
```  1510   fixes f :: "'a \<Rightarrow> nat \<Rightarrow> ennreal"
```
```  1511   shows "(\<And>i. i \<in> I \<Longrightarrow> incseq (f i)) \<Longrightarrow> (SUP n. \<Sum>i\<in>I. f i n) = (\<Sum>i\<in>I. SUP n. f i n)"
```
```  1512   unfolding incseq_def
```
```  1513   by transfer
```
```  1514      (simp add: SUP_ereal_sum incseq_def SUP_upper2 max_absorb2 sum_nonneg)
```
```  1515
```
```  1516 lemma ennreal_liminf_minus:
```
```  1517   fixes f :: "nat \<Rightarrow> ennreal"
```
```  1518   shows "(\<And>n. f n \<le> c) \<Longrightarrow> liminf (\<lambda>n. c - f n) = c - limsup f"
```
```  1519   apply transfer
```
```  1520   apply (simp add: ereal_diff_positive max.absorb2 liminf_ereal_cminus)
```
```  1521   apply (subst max.absorb2)
```
```  1522   apply (rule ereal_diff_positive)
```
```  1523   apply (rule Limsup_bounded)
```
```  1524   apply auto
```
```  1525   done
```
```  1526
```
```  1527 lemma ennreal_continuous_on_cmult:
```
```  1528   "(c::ennreal) < top \<Longrightarrow> continuous_on A f \<Longrightarrow> continuous_on A (\<lambda>x. c * f x)"
```
```  1529   by (transfer fixing: A) (auto intro: continuous_on_cmult_ereal)
```
```  1530
```
```  1531 lemma ennreal_tendsto_cmult:
```
```  1532   "(c::ennreal) < top \<Longrightarrow> (f \<longlongrightarrow> x) F \<Longrightarrow> ((\<lambda>x. c * f x) \<longlongrightarrow> c * x) F"
```
```  1533   by (rule continuous_on_tendsto_compose[where g=f, OF ennreal_continuous_on_cmult, where s=UNIV])
```
```  1534      (auto simp: continuous_on_id)
```
```  1535
```
```  1536 lemma tendsto_ennrealI[intro, simp, tendsto_intros]:
```
```  1537   "(f \<longlongrightarrow> x) F \<Longrightarrow> ((\<lambda>x. ennreal (f x)) \<longlongrightarrow> ennreal x) F"
```
```  1538   by (auto simp: ennreal_def
```
```  1539            intro!: continuous_on_tendsto_compose[OF continuous_on_e2ennreal[of UNIV]] tendsto_max)
```
```  1540
```
```  1541 lemma tendsto_enn2erealI [tendsto_intros]:
```
```  1542   assumes "(f \<longlongrightarrow> l) F"
```
```  1543   shows "((\<lambda>i. enn2ereal(f i)) \<longlongrightarrow> enn2ereal l) F"
```
```  1544 using tendsto_enn2ereal_iff assms by auto
```
```  1545
```
```  1546 lemma tendsto_e2ennrealI [tendsto_intros]:
```
```  1547   assumes "(f \<longlongrightarrow> l) F"
```
```  1548   shows "((\<lambda>i. e2ennreal(f i)) \<longlongrightarrow> e2ennreal l) F"
```
```  1549 proof -
```
```  1550   have *: "e2ennreal (max x 0) = e2ennreal x" for x
```
```  1551     by (simp add: e2ennreal_def max.commute)
```
```  1552   have "((\<lambda>i. max (f i) 0) \<longlongrightarrow> max l 0) F"
```
```  1553     apply (intro tendsto_intros) using assms by auto
```
```  1554   then have "((\<lambda>i. enn2ereal(e2ennreal (max (f i) 0))) \<longlongrightarrow> enn2ereal (e2ennreal (max l 0))) F"
```
```  1555     by (subst enn2ereal_e2ennreal, auto)+
```
```  1556   then have "((\<lambda>i. e2ennreal (max (f i) 0)) \<longlongrightarrow> e2ennreal (max l 0)) F"
```
```  1557     using tendsto_enn2ereal_iff by auto
```
```  1558   then show ?thesis
```
```  1559     unfolding * by auto
```
```  1560 qed
```
```  1561
```
```  1562 lemma ennreal_suminf_minus:
```
```  1563   fixes f g :: "nat \<Rightarrow> ennreal"
```
```  1564   shows "(\<And>i. g i \<le> f i) \<Longrightarrow> suminf f \<noteq> top \<Longrightarrow> suminf g \<noteq> top \<Longrightarrow> (\<Sum>i. f i - g i) = suminf f - suminf g"
```
```  1565   by transfer
```
```  1566      (auto simp add: max.absorb2 ereal_diff_positive suminf_le_pos top_ereal_def intro!: suminf_ereal_minus)
```
```  1567
```
```  1568 lemma ennreal_Sup_countable_SUP:
```
```  1569   "A \<noteq> {} \<Longrightarrow> \<exists>f::nat \<Rightarrow> ennreal. incseq f \<and> range f \<subseteq> A \<and> Sup A = (SUP i. f i)"
```
```  1570   unfolding incseq_def
```
```  1571   apply transfer
```
```  1572   subgoal for A
```
```  1573     using Sup_countable_SUP[of A]
```
```  1574     apply (clarsimp simp add: incseq_def[symmetric] SUP_upper2 max.absorb2 image_subset_iff Sup_upper2 cong: conj_cong)
```
```  1575     subgoal for f
```
```  1576       by (intro exI[of _ f]) auto
```
```  1577     done
```
```  1578   done
```
```  1579
```
```  1580 lemma ennreal_Inf_countable_INF:
```
```  1581   "A \<noteq> {} \<Longrightarrow> \<exists>f::nat \<Rightarrow> ennreal. decseq f \<and> range f \<subseteq> A \<and> Inf A = (INF i. f i)"
```
```  1582   including ennreal.lifting
```
```  1583   unfolding decseq_def
```
```  1584   apply transfer
```
```  1585   subgoal for A
```
```  1586     using Inf_countable_INF[of A]
```
```  1587     apply (clarsimp simp flip: decseq_def)
```
```  1588     subgoal for f
```
```  1589       by (intro exI[of _ f]) auto
```
```  1590     done
```
```  1591   done
```
```  1592
```
```  1593 lemma ennreal_SUP_countable_SUP:
```
```  1594   "A \<noteq> {} \<Longrightarrow> \<exists>f::nat \<Rightarrow> ennreal. range f \<subseteq> g`A \<and> Sup (g ` A) = Sup (f ` UNIV)"
```
```  1595   using ennreal_Sup_countable_SUP [of "g`A"] by auto
```
```  1596
```
```  1597 lemma of_nat_tendsto_top_ennreal: "(\<lambda>n::nat. of_nat n :: ennreal) \<longlonglongrightarrow> top"
```
```  1598   using LIMSEQ_SUP[of "of_nat :: nat \<Rightarrow> ennreal"]
```
```  1599   by (simp add: ennreal_SUP_of_nat_eq_top incseq_def)
```
```  1600
```
```  1601 lemma SUP_sup_continuous_ennreal:
```
```  1602   fixes f :: "ennreal \<Rightarrow> 'a::complete_lattice"
```
```  1603   assumes f: "sup_continuous f" and "I \<noteq> {}"
```
```  1604   shows "(SUP i\<in>I. f (g i)) = f (SUP i\<in>I. g i)"
```
```  1605 proof (rule antisym)
```
```  1606   show "(SUP i\<in>I. f (g i)) \<le> f (SUP i\<in>I. g i)"
```
```  1607     by (rule mono_SUP[OF sup_continuous_mono[OF f]])
```
```  1608   from ennreal_Sup_countable_SUP[of "g`I"] \<open>I \<noteq> {}\<close>
```
```  1609   obtain M :: "nat \<Rightarrow> ennreal" where "incseq M" and M: "range M \<subseteq> g ` I" and eq: "(SUP i \<in> I. g i) = (SUP i. M i)"
```
```  1610     by auto
```
```  1611   have "f (SUP i \<in> I. g i) = (SUP i \<in> range M. f i)"
```
```  1612     unfolding eq sup_continuousD[OF f \<open>mono M\<close>] by (simp add: image_comp)
```
```  1613   also have "\<dots> \<le> (SUP i \<in> I. f (g i))"
```
```  1614     by (insert M, drule SUP_subset_mono) (auto simp add: image_comp)
```
```  1615   finally show "f (SUP i \<in> I. g i) \<le> (SUP i \<in> I. f (g i))" .
```
```  1616 qed
```
```  1617
```
```  1618 lemma ennreal_suminf_SUP_eq:
```
```  1619   fixes f :: "nat \<Rightarrow> nat \<Rightarrow> ennreal"
```
```  1620   shows "(\<And>i. incseq (\<lambda>n. f n i)) \<Longrightarrow> (\<Sum>i. SUP n. f n i) = (SUP n. \<Sum>i. f n i)"
```
```  1621   apply (rule ennreal_suminf_SUP_eq_directed)
```
```  1622   subgoal for N n j
```
```  1623     by (auto simp: incseq_def intro!:exI[of _ "max n j"])
```
```  1624   done
```
```  1625
```
```  1626 lemma ennreal_SUP_add_left:
```
```  1627   fixes c :: ennreal
```
```  1628   shows "I \<noteq> {} \<Longrightarrow> (SUP i\<in>I. f i + c) = (SUP i\<in>I. f i) + c"
```
```  1629   apply transfer
```
```  1630   apply (simp add: SUP_ereal_add_left)
```
```  1631   apply (subst (1 2) max.absorb2)
```
```  1632   apply (auto intro: SUP_upper2 add_nonneg_nonneg)
```
```  1633   done
```
```  1634
```
```  1635 lemma ennreal_SUP_const_minus: (* TODO: rename: ennreal_SUP_const_minus *)
```
```  1636   fixes f :: "'a \<Rightarrow> ennreal"
```
```  1637   shows "I \<noteq> {} \<Longrightarrow> c < top \<Longrightarrow> (INF x\<in>I. c - f x) = c - (SUP x\<in>I. f x)"
```
```  1638   apply (transfer fixing: I)
```
```  1639   unfolding ex_in_conv[symmetric]
```
```  1640   apply (auto simp add: sup_max[symmetric] SUP_upper2 sup_absorb2
```
```  1641               simp del: sup_ereal_def)
```
```  1642   apply (subst INF_ereal_minus_right[symmetric])
```
```  1643   apply (auto simp del: sup_ereal_def simp add: sup_INF)
```
```  1644   done
```
```  1645
```
```  1646 subsection \<open>Approximation lemmas\<close>
```
```  1647
```
```  1648 lemma INF_approx_ennreal:
```
```  1649   fixes x::ennreal and e::real
```
```  1650   assumes "e > 0"
```
```  1651   assumes INF: "x = (INF i \<in> A. f i)"
```
```  1652   assumes "x \<noteq> \<infinity>"
```
```  1653   shows "\<exists>i \<in> A. f i < x + e"
```
```  1654 proof -
```
```  1655   have "(INF i \<in> A. f i) < x + e"
```
```  1656     unfolding INF[symmetric] using \<open>0<e\<close> \<open>x \<noteq> \<infinity>\<close> by (cases x) auto
```
```  1657   then show ?thesis
```
```  1658     unfolding INF_less_iff .
```
```  1659 qed
```
```  1660
```
```  1661 lemma SUP_approx_ennreal:
```
```  1662   fixes x::ennreal and e::real
```
```  1663   assumes "e > 0" "A \<noteq> {}"
```
```  1664   assumes SUP: "x = (SUP i \<in> A. f i)"
```
```  1665   assumes "x \<noteq> \<infinity>"
```
```  1666   shows "\<exists>i \<in> A. x < f i + e"
```
```  1667 proof -
```
```  1668   have "x < x + e"
```
```  1669     using \<open>0<e\<close> \<open>x \<noteq> \<infinity>\<close> by (cases x) auto
```
```  1670   also have "x + e = (SUP i \<in> A. f i + e)"
```
```  1671     unfolding SUP ennreal_SUP_add_left[OF \<open>A \<noteq> {}\<close>] ..
```
```  1672   finally show ?thesis
```
```  1673     unfolding less_SUP_iff .
```
```  1674 qed
```
```  1675
```
```  1676 lemma ennreal_approx_SUP:
```
```  1677   fixes x::ennreal
```
```  1678   assumes f_bound: "\<And>i. i \<in> A \<Longrightarrow> f i \<le> x"
```
```  1679   assumes approx: "\<And>e. (e::real) > 0 \<Longrightarrow> \<exists>i \<in> A. x \<le> f i + e"
```
```  1680   shows "x = (SUP i \<in> A. f i)"
```
```  1681 proof (rule antisym)
```
```  1682   show "x \<le> (SUP i\<in>A. f i)"
```
```  1683   proof (rule ennreal_le_epsilon)
```
```  1684     fix e :: real assume "0 < e"
```
```  1685     from approx[OF this] guess i ..
```
```  1686     then have "x \<le> f i + e"
```
```  1687       by simp
```
```  1688     also have "\<dots> \<le> (SUP i\<in>A. f i) + e"
```
```  1689       by (intro add_mono \<open>i \<in> A\<close> SUP_upper order_refl)
```
```  1690     finally show "x \<le> (SUP i\<in>A. f i) + e" .
```
```  1691   qed
```
```  1692 qed (intro SUP_least f_bound)
```
```  1693
```
```  1694 lemma ennreal_approx_INF:
```
```  1695   fixes x::ennreal
```
```  1696   assumes f_bound: "\<And>i. i \<in> A \<Longrightarrow> x \<le> f i"
```
```  1697   assumes approx: "\<And>e. (e::real) > 0 \<Longrightarrow> \<exists>i \<in> A. f i \<le> x + e"
```
```  1698   shows "x = (INF i \<in> A. f i)"
```
```  1699 proof (rule antisym)
```
```  1700   show "(INF i\<in>A. f i) \<le> x"
```
```  1701   proof (rule ennreal_le_epsilon)
```
```  1702     fix e :: real assume "0 < e"
```
```  1703     from approx[OF this] guess i .. note i = this
```
```  1704     then have "(INF i\<in>A. f i) \<le> f i"
```
```  1705       by (intro INF_lower)
```
```  1706     also have "\<dots> \<le> x + e"
```
```  1707       by fact
```
```  1708     finally show "(INF i\<in>A. f i) \<le> x + e" .
```
```  1709   qed
```
```  1710 qed (intro INF_greatest f_bound)
```
```  1711
```
```  1712 lemma ennreal_approx_unit:
```
```  1713   "(\<And>a::ennreal. 0 < a \<Longrightarrow> a < 1 \<Longrightarrow> a * z \<le> y) \<Longrightarrow> z \<le> y"
```
```  1714   apply (subst SUP_mult_right_ennreal[of "\<lambda>x. x" "{0 <..< 1}" z, simplified])
```
```  1715   apply (rule SUP_least)
```
```  1716   apply auto
```
```  1717   done
```
```  1718
```
```  1719 lemma suminf_ennreal2:
```
```  1720   "(\<And>i. 0 \<le> f i) \<Longrightarrow> summable f \<Longrightarrow> (\<Sum>i. ennreal (f i)) = ennreal (\<Sum>i. f i)"
```
```  1721   using suminf_ennreal_eq by blast
```
```  1722
```
```  1723 lemma less_top_ennreal: "x < top \<longleftrightarrow> (\<exists>r\<ge>0. x = ennreal r)"
```
```  1724   by (cases x) auto
```
```  1725
```
```  1726 lemma tendsto_top_iff_ennreal:
```
```  1727   fixes f :: "'a \<Rightarrow> ennreal"
```
```  1728   shows "(f \<longlongrightarrow> top) F \<longleftrightarrow> (\<forall>l\<ge>0. eventually (\<lambda>x. ennreal l < f x) F)"
```
```  1729   by (auto simp: less_top_ennreal order_tendsto_iff )
```
```  1730
```
```  1731 lemma ennreal_tendsto_top_eq_at_top:
```
```  1732   "((\<lambda>z. ennreal (f z)) \<longlongrightarrow> top) F \<longleftrightarrow> (LIM z F. f z :> at_top)"
```
```  1733   unfolding filterlim_at_top_dense tendsto_top_iff_ennreal
```
```  1734   apply (auto simp: ennreal_less_iff)
```
```  1735   subgoal for y
```
```  1736     by (auto elim!: eventually_mono allE[of _ "max 0 y"])
```
```  1737   done
```
```  1738
```
```  1739 lemma tendsto_0_if_Limsup_eq_0_ennreal:
```
```  1740   fixes f :: "_ \<Rightarrow> ennreal"
```
```  1741   shows "Limsup F f = 0 \<Longrightarrow> (f \<longlongrightarrow> 0) F"
```
```  1742   using Liminf_le_Limsup[of F f] tendsto_iff_Liminf_eq_Limsup[of F f 0]
```
```  1743   by (cases "F = bot") auto
```
```  1744
```
```  1745 lemma diff_le_self_ennreal[simp]: "a - b \<le> (a::ennreal)"
```
```  1746   by (cases a b rule: ennreal2_cases) (auto simp: ennreal_minus)
```
```  1747
```
```  1748 lemma ennreal_ineq_diff_add: "b \<le> a \<Longrightarrow> a = b + (a - b::ennreal)"
```
```  1749   by transfer (auto simp: ereal_diff_positive max.absorb2 ereal_ineq_diff_add)
```
```  1750
```
```  1751 lemma ennreal_mult_strict_left_mono: "(a::ennreal) < c \<Longrightarrow> 0 < b \<Longrightarrow> b < top \<Longrightarrow> b * a < b * c"
```
```  1752   by transfer (auto intro!: ereal_mult_strict_left_mono)
```
```  1753
```
```  1754 lemma ennreal_between: "0 < e \<Longrightarrow> 0 < x \<Longrightarrow> x < top \<Longrightarrow> x - e < (x::ennreal)"
```
```  1755   by transfer (auto intro!: ereal_between)
```
```  1756
```
```  1757 lemma minus_less_iff_ennreal: "b < top \<Longrightarrow> b \<le> a \<Longrightarrow> a - b < c \<longleftrightarrow> a < c + (b::ennreal)"
```
```  1758   by transfer
```
```  1759      (auto simp: top_ereal_def ereal_minus_less le_less)
```
```  1760
```
```  1761 lemma tendsto_zero_ennreal:
```
```  1762   assumes ev: "\<And>r. 0 < r \<Longrightarrow> \<forall>\<^sub>F x in F. f x < ennreal r"
```
```  1763   shows "(f \<longlongrightarrow> 0) F"
```
```  1764 proof (rule order_tendstoI)
```
```  1765   fix e::ennreal assume "e > 0"
```
```  1766   obtain e'::real where "e' > 0" "ennreal e' < e"
```
```  1767     using \<open>0 < e\<close> dense[of 0 "if e = top then 1 else (enn2real e)"]
```
```  1768     by (cases e) (auto simp: ennreal_less_iff)
```
```  1769   from ev[OF \<open>e' > 0\<close>] show "\<forall>\<^sub>F x in F. f x < e"
```
```  1770     by eventually_elim (insert \<open>ennreal e' < e\<close>, auto)
```
```  1771 qed simp
```
```  1772
```
```  1773 lifting_update ennreal.lifting
```
```  1774 lifting_forget ennreal.lifting
```
```  1775
```
```  1776
```
```  1777 subsection \<open>\<^typ>\<open>ennreal\<close> theorems\<close>
```
```  1778
```
```  1779 lemma neq_top_trans: fixes x y :: ennreal shows "\<lbrakk> y \<noteq> top; x \<le> y \<rbrakk> \<Longrightarrow> x \<noteq> top"
```
```  1780 by (auto simp: top_unique)
```
```  1781
```
```  1782 lemma diff_diff_ennreal: fixes a b :: ennreal shows "a \<le> b \<Longrightarrow> b \<noteq> \<infinity> \<Longrightarrow> b - (b - a) = a"
```
```  1783   by (cases a b rule: ennreal2_cases) (auto simp: ennreal_minus top_unique)
```
```  1784
```
```  1785 lemma ennreal_less_one_iff[simp]: "ennreal x < 1 \<longleftrightarrow> x < 1"
```
```  1786   by (cases "0 \<le> x") (auto simp: ennreal_neg ennreal_less_iff simp flip: ennreal_1)
```
```  1787
```
```  1788 lemma SUP_const_minus_ennreal:
```
```  1789   fixes f :: "'a \<Rightarrow> ennreal" shows "I \<noteq> {} \<Longrightarrow> (SUP x\<in>I. c - f x) = c - (INF x\<in>I. f x)"
```
```  1790   including ennreal.lifting
```
```  1791   by (transfer fixing: I)
```
```  1792      (simp add: SUP_sup_distrib[symmetric] SUP_ereal_minus_right
```
```  1793            flip: sup_ereal_def)
```
```  1794
```
```  1795 lemma zero_minus_ennreal[simp]: "0 - (a::ennreal) = 0"
```
```  1796   including ennreal.lifting
```
```  1797   by transfer (simp split: split_max)
```
```  1798
```
```  1799 lemma diff_diff_commute_ennreal:
```
```  1800   fixes a b c :: ennreal shows "a - b - c = a - c - b"
```
```  1801   by (cases a b c rule: ennreal3_cases) (simp_all add: ennreal_minus field_simps)
```
```  1802
```
```  1803 lemma diff_gr0_ennreal: "b < (a::ennreal) \<Longrightarrow> 0 < a - b"
```
```  1804   including ennreal.lifting by transfer (auto simp: ereal_diff_gr0 ereal_diff_positive split: split_max)
```
```  1805
```
```  1806 lemma divide_le_posI_ennreal:
```
```  1807   fixes x y z :: ennreal
```
```  1808   shows "x > 0 \<Longrightarrow> z \<le> x * y \<Longrightarrow> z / x \<le> y"
```
```  1809   by (cases x y z rule: ennreal3_cases)
```
```  1810      (auto simp: divide_ennreal ennreal_mult[symmetric] field_simps top_unique)
```
```  1811
```
```  1812 lemma add_diff_eq_ennreal:
```
```  1813   fixes x y z :: ennreal
```
```  1814   shows "z \<le> y \<Longrightarrow> x + (y - z) = x + y - z"
```
```  1815   including ennreal.lifting
```
```  1816   by transfer
```
```  1817      (insert add_mono[of "0::ereal"], auto simp add: ereal_diff_positive max.absorb2 add_diff_eq_ereal)
```
```  1818
```
```  1819 lemma add_diff_inverse_ennreal:
```
```  1820   fixes x y :: ennreal shows "x \<le> y \<Longrightarrow> x + (y - x) = y"
```
```  1821   by (cases x) (simp_all add: top_unique add_diff_eq_ennreal)
```
```  1822
```
```  1823 lemma add_diff_eq_iff_ennreal[simp]:
```
```  1824   fixes x y :: ennreal shows "x + (y - x) = y \<longleftrightarrow> x \<le> y"
```
```  1825 proof
```
```  1826   assume *: "x + (y - x) = y" show "x \<le> y"
```
```  1827     by (subst *[symmetric]) simp
```
```  1828 qed (simp add: add_diff_inverse_ennreal)
```
```  1829
```
```  1830 lemma add_diff_le_ennreal: "a + b - c \<le> a + (b - c::ennreal)"
```
```  1831   apply (cases a b c rule: ennreal3_cases)
```
```  1832   subgoal for a' b' c'
```
```  1833     by (cases "0 \<le> b' - c'") (simp_all add: ennreal_minus top_add ennreal_neg flip: ennreal_plus)
```
```  1834   apply (simp_all add: top_add flip: ennreal_plus)
```
```  1835   done
```
```  1836
```
```  1837 lemma diff_eq_0_ennreal: "a < top \<Longrightarrow> a \<le> b \<Longrightarrow> a - b = (0::ennreal)"
```
```  1838   using ennreal_minus_pos_iff gr_zeroI not_less by blast
```
```  1839
```
```  1840 lemma diff_diff_ennreal': fixes x y z :: ennreal shows "z \<le> y \<Longrightarrow> y - z \<le> x \<Longrightarrow> x - (y - z) = x + z - y"
```
```  1841   by (cases x; cases y; cases z)
```
```  1842      (auto simp add: top_add add_top minus_top_ennreal ennreal_minus top_unique
```
```  1843            simp flip: ennreal_plus)
```
```  1844
```
```  1845 lemma diff_diff_ennreal'': fixes x y z :: ennreal
```
```  1846   shows "z \<le> y \<Longrightarrow> x - (y - z) = (if y - z \<le> x then x + z - y else 0)"
```
```  1847   by (cases x; cases y; cases z)
```
```  1848      (auto simp add: top_add add_top minus_top_ennreal ennreal_minus top_unique ennreal_neg
```
```  1849            simp flip: ennreal_plus)
```
```  1850
```
```  1851 lemma power_less_top_ennreal: fixes x :: ennreal shows "x ^ n < top \<longleftrightarrow> x < top \<or> n = 0"
```
```  1852   using power_eq_top_ennreal[of x n] by (auto simp: less_top)
```
```  1853
```
```  1854 lemma ennreal_divide_times: "(a / b) * c = a * (c / b :: ennreal)"
```
```  1855   by (simp add: mult.commute ennreal_times_divide)
```
```  1856
```
```  1857 lemma diff_less_top_ennreal: "a - b < top \<longleftrightarrow>  a < (top :: ennreal)"
```
```  1858   by (cases a; cases b) (auto simp: ennreal_minus)
```
```  1859
```
```  1860 lemma divide_less_ennreal: "b \<noteq> 0 \<Longrightarrow> b < top \<Longrightarrow> a / b < c \<longleftrightarrow> a < (c * b :: ennreal)"
```
```  1861   by (cases a; cases b; cases c)
```
```  1862      (auto simp: divide_ennreal ennreal_mult[symmetric] ennreal_less_iff field_simps ennreal_top_mult ennreal_top_divide)
```
```  1863
```
```  1864 lemma one_less_numeral[simp]: "1 < (numeral n::ennreal) \<longleftrightarrow> (num.One < n)"
```
```  1865   by (simp flip: ennreal_1 ennreal_numeral add: ennreal_less_iff)
```
```  1866
```
```  1867 lemma divide_eq_1_ennreal: "a / b = (1::ennreal) \<longleftrightarrow> (b \<noteq> top \<and> b \<noteq> 0 \<and> b = a)"
```
```  1868   by (cases a ; cases b; cases "b = 0") (auto simp: ennreal_top_divide divide_ennreal split: if_split_asm)
```
```  1869
```
```  1870 lemma ennreal_mult_cancel_left: "(a * b = a * c) = (a = top \<and> b \<noteq> 0 \<and> c \<noteq> 0 \<or> a = 0 \<or> b = (c::ennreal))"
```
```  1871   by (cases a; cases b; cases c) (auto simp: ennreal_mult[symmetric] ennreal_mult_top ennreal_top_mult)
```
```  1872
```
```  1873 lemma ennreal_minus_if: "ennreal a - ennreal b = ennreal (if 0 \<le> b then (if b \<le> a then a - b else 0) else a)"
```
```  1874   by (auto simp: ennreal_minus ennreal_neg)
```
```  1875
```
```  1876 lemma ennreal_plus_if: "ennreal a + ennreal b = ennreal (if 0 \<le> a then (if 0 \<le> b then a + b else a) else b)"
```
```  1877   by (auto simp: ennreal_neg)
```
```  1878
```
```  1879 lemma power_le_one_iff: "0 \<le> (a::real) \<Longrightarrow> a ^ n \<le> 1 \<longleftrightarrow> (n = 0 \<or> a \<le> 1)"
```
```  1880   by (metis (mono_tags, hide_lams) le_less neq0_conv not_le one_le_power power_0 power_eq_imp_eq_base power_le_one zero_le_one)
```
```  1881
```
```  1882 lemma ennreal_diff_le_mono_left: "a \<le> b \<Longrightarrow> a - c \<le> (b::ennreal)"
```
```  1883   using ennreal_mono_minus[of 0 c a, THEN order_trans, of b] by simp
```
```  1884
```
```  1885 lemma ennreal_minus_le_iff: "a - b \<le> c \<longleftrightarrow> (a \<le> b + (c::ennreal) \<and> (a = top \<and> b = top \<longrightarrow> c = top))"
```
```  1886   by (cases a; cases b; cases c)
```
```  1887      (auto simp: top_unique top_add add_top ennreal_minus simp flip: ennreal_plus)
```
```  1888
```
```  1889 lemma ennreal_le_minus_iff: "a \<le> b - c \<longleftrightarrow> (a + c \<le> (b::ennreal) \<or> (a = 0 \<and> b \<le> c))"
```
```  1890   by (cases a; cases b; cases c)
```
```  1891      (auto simp: top_unique top_add add_top ennreal_minus ennreal_le_iff2
```
```  1892            simp flip: ennreal_plus)
```
```  1893
```
```  1894 lemma diff_add_eq_diff_diff_swap_ennreal: "x - (y + z :: ennreal) = x - y - z"
```
```  1895   by (cases x; cases y; cases z)
```
```  1896      (auto simp: ennreal_minus_if add_top top_add simp flip: ennreal_plus)
```
```  1897
```
```  1898 lemma diff_add_assoc2_ennreal: "b \<le> a \<Longrightarrow> (a - b + c::ennreal) = a + c - b"
```
```  1899   by (cases a; cases b; cases c)
```
```  1900      (auto simp add: ennreal_minus_if ennreal_plus_if add_top top_add top_unique simp del: ennreal_plus)
```
```  1901
```
```  1902 lemma diff_gt_0_iff_gt_ennreal: "0 < a - b \<longleftrightarrow> (a = top \<and> b = top \<or> b < (a::ennreal))"
```
```  1903   by (cases a; cases b) (auto simp: ennreal_minus_if ennreal_less_iff)
```
```  1904
```
```  1905 lemma diff_eq_0_iff_ennreal: "(a - b::ennreal) = 0 \<longleftrightarrow> (a < top \<and> a \<le> b)"
```
```  1906   by (cases a) (auto simp: ennreal_minus_eq_0 diff_eq_0_ennreal)
```
```  1907
```
```  1908 lemma add_diff_self_ennreal: "a + (b - a::ennreal) = (if a \<le> b then b else a)"
```
```  1909   by (auto simp: diff_eq_0_iff_ennreal less_top)
```
```  1910
```
```  1911 lemma diff_add_self_ennreal: "(b - a + a::ennreal) = (if a \<le> b then b else a)"
```
```  1912   by (auto simp: diff_add_cancel_ennreal diff_eq_0_iff_ennreal less_top)
```
```  1913
```
```  1914 lemma ennreal_minus_cancel_iff:
```
```  1915   fixes a b c :: ennreal
```
```  1916   shows "a - b = a - c \<longleftrightarrow> (b = c \<or> (a \<le> b \<and> a \<le> c) \<or> a = top)"
```
```  1917   by (cases a; cases b; cases c) (auto simp: ennreal_minus_if)
```
```  1918
```
```  1919 text \<open>The next lemma is wrong for \$a = top\$, for \$b = c = 1\$ for instance.\<close>
```
```  1920
```
```  1921 lemma ennreal_right_diff_distrib:
```
```  1922   fixes a b c::ennreal
```
```  1923   assumes "a \<noteq> top"
```
```  1924   shows "a * (b - c) = a * b - a * c"
```
```  1925   apply (cases a, cases b, cases c, auto simp add: assms)
```
```  1926   apply (metis (mono_tags, lifting) ennreal_minus ennreal_mult' linordered_field_class.sign_simps(38) split_mult_pos_le)
```
```  1927   apply (metis ennreal_minus_zero ennreal_mult_cancel_left ennreal_top_eq_mult_iff minus_top_ennreal mult_eq_0_iff top_neq_ennreal)
```
```  1928   apply (metis ennreal_minus_eq_top ennreal_minus_zero ennreal_mult_eq_top_iff mult_eq_0_iff)
```
```  1929   done
```
```  1930
```
```  1931 lemma SUP_diff_ennreal:
```
```  1932   "c < top \<Longrightarrow> (SUP i\<in>I. f i - c :: ennreal) = (SUP i\<in>I. f i) - c"
```
```  1933   by (auto intro!: SUP_eqI ennreal_minus_mono SUP_least intro: SUP_upper
```
```  1934            simp: ennreal_minus_cancel_iff ennreal_minus_le_iff less_top[symmetric])
```
```  1935
```
```  1936 lemma ennreal_SUP_add_right:
```
```  1937   fixes c :: ennreal shows "I \<noteq> {} \<Longrightarrow> c + (SUP i\<in>I. f i) = (SUP i\<in>I. c + f i)"
```
```  1938   using ennreal_SUP_add_left[of I f c] by (simp add: add.commute)
```
```  1939
```
```  1940 lemma SUP_add_directed_ennreal:
```
```  1941   fixes f g :: "_ \<Rightarrow> ennreal"
```
```  1942   assumes directed: "\<And>i j. i \<in> I \<Longrightarrow> j \<in> I \<Longrightarrow> \<exists>k\<in>I. f i + g j \<le> f k + g k"
```
```  1943   shows "(SUP i\<in>I. f i + g i) = (SUP i\<in>I. f i) + (SUP i\<in>I. g i)"
```
```  1944 proof cases
```
```  1945   assume "I = {}" then show ?thesis
```
```  1946     by (simp add: bot_ereal_def)
```
```  1947 next
```
```  1948   assume "I \<noteq> {}"
```
```  1949   show ?thesis
```
```  1950   proof (rule antisym)
```
```  1951     show "(SUP i\<in>I. f i + g i) \<le> (SUP i\<in>I. f i) + (SUP i\<in>I. g i)"
```
```  1952       by (rule SUP_least; intro add_mono SUP_upper)
```
```  1953   next
```
```  1954     have "(SUP i\<in>I. f i) + (SUP i\<in>I. g i) = (SUP i\<in>I. f i + (SUP i\<in>I. g i))"
```
```  1955       by (intro ennreal_SUP_add_left[symmetric] \<open>I \<noteq> {}\<close>)
```
```  1956     also have "\<dots> = (SUP i\<in>I. (SUP j\<in>I. f i + g j))"
```
```  1957       using \<open>I \<noteq> {}\<close> by (simp add: ennreal_SUP_add_right)
```
```  1958     also have "\<dots> \<le> (SUP i\<in>I. f i + g i)"
```
```  1959       using directed by (intro SUP_least) (blast intro: SUP_upper2)
```
```  1960     finally show "(SUP i\<in>I. f i) + (SUP i\<in>I. g i) \<le> (SUP i\<in>I. f i + g i)" .
```
```  1961   qed
```
```  1962 qed
```
```  1963
```
```  1964 lemma enn2real_eq_0_iff: "enn2real x = 0 \<longleftrightarrow> x = 0 \<or> x = top"
```
```  1965   by (cases x) auto
```
```  1966
```
```  1967 lemma continuous_on_diff_ennreal:
```
```  1968   "continuous_on A f \<Longrightarrow> continuous_on A g \<Longrightarrow> (\<And>x. x \<in> A \<Longrightarrow> f x \<noteq> top) \<Longrightarrow> (\<And>x. x \<in> A \<Longrightarrow> g x \<noteq> top) \<Longrightarrow> continuous_on A (\<lambda>z. f z - g z::ennreal)"
```
```  1969   including ennreal.lifting
```
```  1970 proof (transfer fixing: A, simp add: top_ereal_def)
```
```  1971   fix f g :: "'a \<Rightarrow> ereal" assume "\<forall>x. 0 \<le> f x" "\<forall>x. 0 \<le> g x" "continuous_on A f" "continuous_on A g"
```
```  1972   moreover assume "f x \<noteq> \<infinity>" "g x \<noteq> \<infinity>" if "x \<in> A" for x
```
```  1973   ultimately show "continuous_on A (\<lambda>z. max 0 (f z - g z))"
```
```  1974     by (intro continuous_on_max continuous_on_const continuous_on_diff_ereal) auto
```
```  1975 qed
```
```  1976
```
```  1977 lemma tendsto_diff_ennreal:
```
```  1978   "(f \<longlongrightarrow> x) F \<Longrightarrow> (g \<longlongrightarrow> y) F \<Longrightarrow> x \<noteq> top \<Longrightarrow> y \<noteq> top \<Longrightarrow> ((\<lambda>z. f z - g z::ennreal) \<longlongrightarrow> x - y) F"
```
```  1979   using continuous_on_tendsto_compose[where f="\<lambda>x. fst x - snd x::ennreal" and s="{(x, y). x \<noteq> top \<and> y \<noteq> top}" and g="\<lambda>x. (f x, g x)" and l="(x, y)" and F="F",
```
```  1980     OF continuous_on_diff_ennreal]
```
```  1981   by (auto simp: tendsto_Pair eventually_conj_iff less_top order_tendstoD continuous_on_fst continuous_on_snd continuous_on_id)
```
```  1982
```
```  1983 declare lim_real_of_ereal [tendsto_intros]
```
```  1984
```
```  1985 lemma tendsto_enn2real [tendsto_intros]:
```
```  1986   assumes "(u \<longlongrightarrow> ennreal l) F" "l \<ge> 0"
```
```  1987   shows "((\<lambda>n. enn2real (u n)) \<longlongrightarrow> l) F"
```
```  1988   unfolding enn2real_def
```
```  1989   apply (intro tendsto_intros)
```
```  1990   apply (subst enn2ereal_ennreal[symmetric])
```
```  1991   by (intro tendsto_intros assms)+
```
```  1992
```
```  1993 end
```