src/HOL/OrderedGroup.thy
author obua
Mon Mar 07 18:19:55 2005 +0100 (2005-03-07)
changeset 15580 900291ee0af8
parent 15539 333a88244569
child 16417 9bc16273c2d4
permissions -rw-r--r--
Cleaning up HOL/Matrix
     1 (*  Title:   HOL/OrderedGroup.thy
     2     ID:      $Id$
     3     Author:  Gertrud Bauer, Steven Obua, Lawrence C Paulson, and Markus Wenzel
     4 *)
     5 
     6 header {* Ordered Groups *}
     7 
     8 theory OrderedGroup
     9 imports Inductive LOrder
    10 files "../Provers/Arith/abel_cancel.ML"
    11 begin
    12 
    13 text {*
    14   The theory of partially ordered groups is taken from the books:
    15   \begin{itemize}
    16   \item \emph{Lattice Theory} by Garret Birkhoff, American Mathematical Society 1979 
    17   \item \emph{Partially Ordered Algebraic Systems}, Pergamon Press 1963
    18   \end{itemize}
    19   Most of the used notions can also be looked up in 
    20   \begin{itemize}
    21   \item \url{http://www.mathworld.com} by Eric Weisstein et. al.
    22   \item \emph{Algebra I} by van der Waerden, Springer.
    23   \end{itemize}
    24 *}
    25 
    26 subsection {* Semigroups, Groups *}
    27  
    28 axclass semigroup_add \<subseteq> plus
    29   add_assoc: "(a + b) + c = a + (b + c)"
    30 
    31 axclass ab_semigroup_add \<subseteq> semigroup_add
    32   add_commute: "a + b = b + a"
    33 
    34 lemma add_left_commute: "a + (b + c) = b + (a + (c::'a::ab_semigroup_add))"
    35   by (rule mk_left_commute [of "op +", OF add_assoc add_commute])
    36 
    37 theorems add_ac = add_assoc add_commute add_left_commute
    38 
    39 axclass semigroup_mult \<subseteq> times
    40   mult_assoc: "(a * b) * c = a * (b * c)"
    41 
    42 axclass ab_semigroup_mult \<subseteq> semigroup_mult
    43   mult_commute: "a * b = b * a"
    44 
    45 lemma mult_left_commute: "a * (b * c) = b * (a * (c::'a::ab_semigroup_mult))"
    46   by (rule mk_left_commute [of "op *", OF mult_assoc mult_commute])
    47 
    48 theorems mult_ac = mult_assoc mult_commute mult_left_commute
    49 
    50 axclass comm_monoid_add \<subseteq> zero, ab_semigroup_add
    51   add_0[simp]: "0 + a = a"
    52 
    53 axclass monoid_mult \<subseteq> one, semigroup_mult
    54   mult_1_left[simp]: "1 * a  = a"
    55   mult_1_right[simp]: "a * 1 = a"
    56 
    57 axclass comm_monoid_mult \<subseteq> one, ab_semigroup_mult
    58   mult_1: "1 * a = a"
    59 
    60 instance comm_monoid_mult \<subseteq> monoid_mult
    61 by (intro_classes, insert mult_1, simp_all add: mult_commute, auto)
    62 
    63 axclass cancel_semigroup_add \<subseteq> semigroup_add
    64   add_left_imp_eq: "a + b = a + c \<Longrightarrow> b = c"
    65   add_right_imp_eq: "b + a = c + a \<Longrightarrow> b = c"
    66 
    67 axclass cancel_ab_semigroup_add \<subseteq> ab_semigroup_add
    68   add_imp_eq: "a + b = a + c \<Longrightarrow> b = c"
    69 
    70 instance cancel_ab_semigroup_add \<subseteq> cancel_semigroup_add
    71 proof
    72   {
    73     fix a b c :: 'a
    74     assume "a + b = a + c"
    75     thus "b = c" by (rule add_imp_eq)
    76   }
    77   note f = this
    78   fix a b c :: 'a
    79   assume "b + a = c + a"
    80   hence "a + b = a + c" by (simp only: add_commute)
    81   thus "b = c" by (rule f)
    82 qed
    83 
    84 axclass ab_group_add \<subseteq> minus, comm_monoid_add
    85   left_minus[simp]: " - a + a = 0"
    86   diff_minus: "a - b = a + (-b)"
    87 
    88 instance ab_group_add \<subseteq> cancel_ab_semigroup_add
    89 proof 
    90   fix a b c :: 'a
    91   assume "a + b = a + c"
    92   hence "-a + a + b = -a + a + c" by (simp only: add_assoc)
    93   thus "b = c" by simp 
    94 qed
    95 
    96 lemma add_0_right [simp]: "a + 0 = (a::'a::comm_monoid_add)"
    97 proof -
    98   have "a + 0 = 0 + a" by (simp only: add_commute)
    99   also have "... = a" by simp
   100   finally show ?thesis .
   101 qed
   102 
   103 lemma add_left_cancel [simp]:
   104      "(a + b = a + c) = (b = (c::'a::cancel_semigroup_add))"
   105 by (blast dest: add_left_imp_eq) 
   106 
   107 lemma add_right_cancel [simp]:
   108      "(b + a = c + a) = (b = (c::'a::cancel_semigroup_add))"
   109   by (blast dest: add_right_imp_eq)
   110 
   111 lemma right_minus [simp]: "a + -(a::'a::ab_group_add) = 0"
   112 proof -
   113   have "a + -a = -a + a" by (simp add: add_ac)
   114   also have "... = 0" by simp
   115   finally show ?thesis .
   116 qed
   117 
   118 lemma right_minus_eq: "(a - b = 0) = (a = (b::'a::ab_group_add))"
   119 proof
   120   have "a = a - b + b" by (simp add: diff_minus add_ac)
   121   also assume "a - b = 0"
   122   finally show "a = b" by simp
   123 next
   124   assume "a = b"
   125   thus "a - b = 0" by (simp add: diff_minus)
   126 qed
   127 
   128 lemma minus_minus [simp]: "- (- (a::'a::ab_group_add)) = a"
   129 proof (rule add_left_cancel [of "-a", THEN iffD1])
   130   show "(-a + -(-a) = -a + a)"
   131   by simp
   132 qed
   133 
   134 lemma equals_zero_I: "a+b = 0 ==> -a = (b::'a::ab_group_add)"
   135 apply (rule right_minus_eq [THEN iffD1, symmetric])
   136 apply (simp add: diff_minus add_commute) 
   137 done
   138 
   139 lemma minus_zero [simp]: "- 0 = (0::'a::ab_group_add)"
   140 by (simp add: equals_zero_I)
   141 
   142 lemma diff_self [simp]: "a - (a::'a::ab_group_add) = 0"
   143   by (simp add: diff_minus)
   144 
   145 lemma diff_0 [simp]: "(0::'a::ab_group_add) - a = -a"
   146 by (simp add: diff_minus)
   147 
   148 lemma diff_0_right [simp]: "a - (0::'a::ab_group_add) = a" 
   149 by (simp add: diff_minus)
   150 
   151 lemma diff_minus_eq_add [simp]: "a - - b = a + (b::'a::ab_group_add)"
   152 by (simp add: diff_minus)
   153 
   154 lemma neg_equal_iff_equal [simp]: "(-a = -b) = (a = (b::'a::ab_group_add))" 
   155 proof 
   156   assume "- a = - b"
   157   hence "- (- a) = - (- b)"
   158     by simp
   159   thus "a=b" by simp
   160 next
   161   assume "a=b"
   162   thus "-a = -b" by simp
   163 qed
   164 
   165 lemma neg_equal_0_iff_equal [simp]: "(-a = 0) = (a = (0::'a::ab_group_add))"
   166 by (subst neg_equal_iff_equal [symmetric], simp)
   167 
   168 lemma neg_0_equal_iff_equal [simp]: "(0 = -a) = (0 = (a::'a::ab_group_add))"
   169 by (subst neg_equal_iff_equal [symmetric], simp)
   170 
   171 text{*The next two equations can make the simplifier loop!*}
   172 
   173 lemma equation_minus_iff: "(a = - b) = (b = - (a::'a::ab_group_add))"
   174 proof -
   175   have "(- (-a) = - b) = (- a = b)" by (rule neg_equal_iff_equal)
   176   thus ?thesis by (simp add: eq_commute)
   177 qed
   178 
   179 lemma minus_equation_iff: "(- a = b) = (- (b::'a::ab_group_add) = a)"
   180 proof -
   181   have "(- a = - (-b)) = (a = -b)" by (rule neg_equal_iff_equal)
   182   thus ?thesis by (simp add: eq_commute)
   183 qed
   184 
   185 lemma minus_add_distrib [simp]: "- (a + b) = -a + -(b::'a::ab_group_add)"
   186 apply (rule equals_zero_I)
   187 apply (simp add: add_ac) 
   188 done
   189 
   190 lemma minus_diff_eq [simp]: "- (a - b) = b - (a::'a::ab_group_add)"
   191 by (simp add: diff_minus add_commute)
   192 
   193 subsection {* (Partially) Ordered Groups *} 
   194 
   195 axclass pordered_ab_semigroup_add \<subseteq> order, ab_semigroup_add
   196   add_left_mono: "a \<le> b \<Longrightarrow> c + a \<le> c + b"
   197 
   198 axclass pordered_cancel_ab_semigroup_add \<subseteq> pordered_ab_semigroup_add, cancel_ab_semigroup_add
   199 
   200 instance pordered_cancel_ab_semigroup_add \<subseteq> pordered_ab_semigroup_add ..
   201 
   202 axclass pordered_ab_semigroup_add_imp_le \<subseteq> pordered_cancel_ab_semigroup_add
   203   add_le_imp_le_left: "c + a \<le> c + b \<Longrightarrow> a \<le> b"
   204 
   205 axclass pordered_ab_group_add \<subseteq> ab_group_add, pordered_ab_semigroup_add
   206 
   207 instance pordered_ab_group_add \<subseteq> pordered_ab_semigroup_add_imp_le
   208 proof
   209   fix a b c :: 'a
   210   assume "c + a \<le> c + b"
   211   hence "(-c) + (c + a) \<le> (-c) + (c + b)" by (rule add_left_mono)
   212   hence "((-c) + c) + a \<le> ((-c) + c) + b" by (simp only: add_assoc)
   213   thus "a \<le> b" by simp
   214 qed
   215 
   216 axclass ordered_cancel_ab_semigroup_add \<subseteq> pordered_cancel_ab_semigroup_add, linorder
   217 
   218 instance ordered_cancel_ab_semigroup_add \<subseteq> pordered_ab_semigroup_add_imp_le
   219 proof
   220   fix a b c :: 'a
   221   assume le: "c + a <= c + b"  
   222   show "a <= b"
   223   proof (rule ccontr)
   224     assume w: "~ a \<le> b"
   225     hence "b <= a" by (simp add: linorder_not_le)
   226     hence le2: "c+b <= c+a" by (rule add_left_mono)
   227     have "a = b" 
   228       apply (insert le)
   229       apply (insert le2)
   230       apply (drule order_antisym, simp_all)
   231       done
   232     with w  show False 
   233       by (simp add: linorder_not_le [symmetric])
   234   qed
   235 qed
   236 
   237 lemma add_right_mono: "a \<le> (b::'a::pordered_ab_semigroup_add) ==> a + c \<le> b + c"
   238 by (simp add: add_commute[of _ c] add_left_mono)
   239 
   240 text {* non-strict, in both arguments *}
   241 lemma add_mono:
   242      "[|a \<le> b;  c \<le> d|] ==> a + c \<le> b + (d::'a::pordered_ab_semigroup_add)"
   243   apply (erule add_right_mono [THEN order_trans])
   244   apply (simp add: add_commute add_left_mono)
   245   done
   246 
   247 lemma add_strict_left_mono:
   248      "a < b ==> c + a < c + (b::'a::pordered_cancel_ab_semigroup_add)"
   249  by (simp add: order_less_le add_left_mono) 
   250 
   251 lemma add_strict_right_mono:
   252      "a < b ==> a + c < b + (c::'a::pordered_cancel_ab_semigroup_add)"
   253  by (simp add: add_commute [of _ c] add_strict_left_mono)
   254 
   255 text{*Strict monotonicity in both arguments*}
   256 lemma add_strict_mono: "[|a<b; c<d|] ==> a + c < b + (d::'a::pordered_cancel_ab_semigroup_add)"
   257 apply (erule add_strict_right_mono [THEN order_less_trans])
   258 apply (erule add_strict_left_mono)
   259 done
   260 
   261 lemma add_less_le_mono:
   262      "[| a<b; c\<le>d |] ==> a + c < b + (d::'a::pordered_cancel_ab_semigroup_add)"
   263 apply (erule add_strict_right_mono [THEN order_less_le_trans])
   264 apply (erule add_left_mono) 
   265 done
   266 
   267 lemma add_le_less_mono:
   268      "[| a\<le>b; c<d |] ==> a + c < b + (d::'a::pordered_cancel_ab_semigroup_add)"
   269 apply (erule add_right_mono [THEN order_le_less_trans])
   270 apply (erule add_strict_left_mono) 
   271 done
   272 
   273 lemma add_less_imp_less_left:
   274       assumes less: "c + a < c + b"  shows "a < (b::'a::pordered_ab_semigroup_add_imp_le)"
   275 proof -
   276   from less have le: "c + a <= c + b" by (simp add: order_le_less)
   277   have "a <= b" 
   278     apply (insert le)
   279     apply (drule add_le_imp_le_left)
   280     by (insert le, drule add_le_imp_le_left, assumption)
   281   moreover have "a \<noteq> b"
   282   proof (rule ccontr)
   283     assume "~(a \<noteq> b)"
   284     then have "a = b" by simp
   285     then have "c + a = c + b" by simp
   286     with less show "False"by simp
   287   qed
   288   ultimately show "a < b" by (simp add: order_le_less)
   289 qed
   290 
   291 lemma add_less_imp_less_right:
   292       "a + c < b + c ==> a < (b::'a::pordered_ab_semigroup_add_imp_le)"
   293 apply (rule add_less_imp_less_left [of c])
   294 apply (simp add: add_commute)  
   295 done
   296 
   297 lemma add_less_cancel_left [simp]:
   298     "(c+a < c+b) = (a < (b::'a::pordered_ab_semigroup_add_imp_le))"
   299 by (blast intro: add_less_imp_less_left add_strict_left_mono) 
   300 
   301 lemma add_less_cancel_right [simp]:
   302     "(a+c < b+c) = (a < (b::'a::pordered_ab_semigroup_add_imp_le))"
   303 by (blast intro: add_less_imp_less_right add_strict_right_mono)
   304 
   305 lemma add_le_cancel_left [simp]:
   306     "(c+a \<le> c+b) = (a \<le> (b::'a::pordered_ab_semigroup_add_imp_le))"
   307 by (auto, drule add_le_imp_le_left, simp_all add: add_left_mono) 
   308 
   309 lemma add_le_cancel_right [simp]:
   310     "(a+c \<le> b+c) = (a \<le> (b::'a::pordered_ab_semigroup_add_imp_le))"
   311 by (simp add: add_commute[of a c] add_commute[of b c])
   312 
   313 lemma add_le_imp_le_right:
   314       "a + c \<le> b + c ==> a \<le> (b::'a::pordered_ab_semigroup_add_imp_le)"
   315 by simp
   316 
   317 lemma add_increasing:
   318   fixes c :: "'a::{pordered_ab_semigroup_add_imp_le, comm_monoid_add}"
   319   shows  "[|0\<le>a; b\<le>c|] ==> b \<le> a + c"
   320 by (insert add_mono [of 0 a b c], simp)
   321 
   322 lemma add_increasing2:
   323   fixes c :: "'a::{pordered_ab_semigroup_add_imp_le, comm_monoid_add}"
   324   shows  "[|0\<le>c; b\<le>a|] ==> b \<le> a + c"
   325 by (simp add:add_increasing add_commute[of a])
   326 
   327 lemma add_strict_increasing:
   328   fixes c :: "'a::{pordered_ab_semigroup_add_imp_le, comm_monoid_add}"
   329   shows "[|0<a; b\<le>c|] ==> b < a + c"
   330 by (insert add_less_le_mono [of 0 a b c], simp)
   331 
   332 lemma add_strict_increasing2:
   333   fixes c :: "'a::{pordered_ab_semigroup_add_imp_le, comm_monoid_add}"
   334   shows "[|0\<le>a; b<c|] ==> b < a + c"
   335 by (insert add_le_less_mono [of 0 a b c], simp)
   336 
   337 
   338 subsection {* Ordering Rules for Unary Minus *}
   339 
   340 lemma le_imp_neg_le:
   341       assumes "a \<le> (b::'a::{pordered_ab_semigroup_add_imp_le, ab_group_add})" shows "-b \<le> -a"
   342 proof -
   343   have "-a+a \<le> -a+b"
   344     by (rule add_left_mono) 
   345   hence "0 \<le> -a+b"
   346     by simp
   347   hence "0 + (-b) \<le> (-a + b) + (-b)"
   348     by (rule add_right_mono) 
   349   thus ?thesis
   350     by (simp add: add_assoc)
   351 qed
   352 
   353 lemma neg_le_iff_le [simp]: "(-b \<le> -a) = (a \<le> (b::'a::pordered_ab_group_add))"
   354 proof 
   355   assume "- b \<le> - a"
   356   hence "- (- a) \<le> - (- b)"
   357     by (rule le_imp_neg_le)
   358   thus "a\<le>b" by simp
   359 next
   360   assume "a\<le>b"
   361   thus "-b \<le> -a" by (rule le_imp_neg_le)
   362 qed
   363 
   364 lemma neg_le_0_iff_le [simp]: "(-a \<le> 0) = (0 \<le> (a::'a::pordered_ab_group_add))"
   365 by (subst neg_le_iff_le [symmetric], simp)
   366 
   367 lemma neg_0_le_iff_le [simp]: "(0 \<le> -a) = (a \<le> (0::'a::pordered_ab_group_add))"
   368 by (subst neg_le_iff_le [symmetric], simp)
   369 
   370 lemma neg_less_iff_less [simp]: "(-b < -a) = (a < (b::'a::pordered_ab_group_add))"
   371 by (force simp add: order_less_le) 
   372 
   373 lemma neg_less_0_iff_less [simp]: "(-a < 0) = (0 < (a::'a::pordered_ab_group_add))"
   374 by (subst neg_less_iff_less [symmetric], simp)
   375 
   376 lemma neg_0_less_iff_less [simp]: "(0 < -a) = (a < (0::'a::pordered_ab_group_add))"
   377 by (subst neg_less_iff_less [symmetric], simp)
   378 
   379 text{*The next several equations can make the simplifier loop!*}
   380 
   381 lemma less_minus_iff: "(a < - b) = (b < - (a::'a::pordered_ab_group_add))"
   382 proof -
   383   have "(- (-a) < - b) = (b < - a)" by (rule neg_less_iff_less)
   384   thus ?thesis by simp
   385 qed
   386 
   387 lemma minus_less_iff: "(- a < b) = (- b < (a::'a::pordered_ab_group_add))"
   388 proof -
   389   have "(- a < - (-b)) = (- b < a)" by (rule neg_less_iff_less)
   390   thus ?thesis by simp
   391 qed
   392 
   393 lemma le_minus_iff: "(a \<le> - b) = (b \<le> - (a::'a::pordered_ab_group_add))"
   394 proof -
   395   have mm: "!! a (b::'a). (-(-a)) < -b \<Longrightarrow> -(-b) < -a" by (simp only: minus_less_iff)
   396   have "(- (- a) <= -b) = (b <= - a)" 
   397     apply (auto simp only: order_le_less)
   398     apply (drule mm)
   399     apply (simp_all)
   400     apply (drule mm[simplified], assumption)
   401     done
   402   then show ?thesis by simp
   403 qed
   404 
   405 lemma minus_le_iff: "(- a \<le> b) = (- b \<le> (a::'a::pordered_ab_group_add))"
   406 by (auto simp add: order_le_less minus_less_iff)
   407 
   408 lemma add_diff_eq: "a + (b - c) = (a + b) - (c::'a::ab_group_add)"
   409 by (simp add: diff_minus add_ac)
   410 
   411 lemma diff_add_eq: "(a - b) + c = (a + c) - (b::'a::ab_group_add)"
   412 by (simp add: diff_minus add_ac)
   413 
   414 lemma diff_eq_eq: "(a-b = c) = (a = c + (b::'a::ab_group_add))"
   415 by (auto simp add: diff_minus add_assoc)
   416 
   417 lemma eq_diff_eq: "(a = c-b) = (a + (b::'a::ab_group_add) = c)"
   418 by (auto simp add: diff_minus add_assoc)
   419 
   420 lemma diff_diff_eq: "(a - b) - c = a - (b + (c::'a::ab_group_add))"
   421 by (simp add: diff_minus add_ac)
   422 
   423 lemma diff_diff_eq2: "a - (b - c) = (a + c) - (b::'a::ab_group_add)"
   424 by (simp add: diff_minus add_ac)
   425 
   426 lemma diff_add_cancel: "a - b + b = (a::'a::ab_group_add)"
   427 by (simp add: diff_minus add_ac)
   428 
   429 lemma add_diff_cancel: "a + b - b = (a::'a::ab_group_add)"
   430 by (simp add: diff_minus add_ac)
   431 
   432 text{*Further subtraction laws*}
   433 
   434 lemma less_iff_diff_less_0: "(a < b) = (a - b < (0::'a::pordered_ab_group_add))"
   435 proof -
   436   have  "(a < b) = (a + (- b) < b + (-b))"  
   437     by (simp only: add_less_cancel_right)
   438   also have "... =  (a - b < 0)" by (simp add: diff_minus)
   439   finally show ?thesis .
   440 qed
   441 
   442 lemma diff_less_eq: "(a-b < c) = (a < c + (b::'a::pordered_ab_group_add))"
   443 apply (subst less_iff_diff_less_0 [of a])
   444 apply (rule less_iff_diff_less_0 [of _ c, THEN ssubst])
   445 apply (simp add: diff_minus add_ac)
   446 done
   447 
   448 lemma less_diff_eq: "(a < c-b) = (a + (b::'a::pordered_ab_group_add) < c)"
   449 apply (subst less_iff_diff_less_0 [of "a+b"])
   450 apply (subst less_iff_diff_less_0 [of a])
   451 apply (simp add: diff_minus add_ac)
   452 done
   453 
   454 lemma diff_le_eq: "(a-b \<le> c) = (a \<le> c + (b::'a::pordered_ab_group_add))"
   455 by (auto simp add: order_le_less diff_less_eq diff_add_cancel add_diff_cancel)
   456 
   457 lemma le_diff_eq: "(a \<le> c-b) = (a + (b::'a::pordered_ab_group_add) \<le> c)"
   458 by (auto simp add: order_le_less less_diff_eq diff_add_cancel add_diff_cancel)
   459 
   460 text{*This list of rewrites simplifies (in)equalities by bringing subtractions
   461   to the top and then moving negative terms to the other side.
   462   Use with @{text add_ac}*}
   463 lemmas compare_rls =
   464        diff_minus [symmetric]
   465        add_diff_eq diff_add_eq diff_diff_eq diff_diff_eq2
   466        diff_less_eq less_diff_eq diff_le_eq le_diff_eq
   467        diff_eq_eq eq_diff_eq
   468 
   469 
   470 subsection{*Lemmas for the @{text cancel_numerals} simproc*}
   471 
   472 lemma eq_iff_diff_eq_0: "(a = b) = (a-b = (0::'a::ab_group_add))"
   473 by (simp add: compare_rls)
   474 
   475 lemma le_iff_diff_le_0: "(a \<le> b) = (a-b \<le> (0::'a::pordered_ab_group_add))"
   476 by (simp add: compare_rls)
   477 
   478 subsection {* Lattice Ordered (Abelian) Groups *}
   479 
   480 axclass lordered_ab_group_meet < pordered_ab_group_add, meet_semilorder
   481 
   482 axclass lordered_ab_group_join < pordered_ab_group_add, join_semilorder
   483 
   484 lemma add_meet_distrib_left: "a + (meet b c) = meet (a + b) (a + (c::'a::{pordered_ab_group_add, meet_semilorder}))"
   485 apply (rule order_antisym)
   486 apply (rule meet_imp_le, simp_all add: meet_join_le)
   487 apply (rule add_le_imp_le_left [of "-a"])
   488 apply (simp only: add_assoc[symmetric], simp)
   489 apply (rule meet_imp_le)
   490 apply (rule add_le_imp_le_left[of "a"], simp only: add_assoc[symmetric], simp add: meet_join_le)+
   491 done
   492 
   493 lemma add_join_distrib_left: "a + (join b c) = join (a + b) (a+ (c::'a::{pordered_ab_group_add, join_semilorder}))" 
   494 apply (rule order_antisym)
   495 apply (rule add_le_imp_le_left [of "-a"])
   496 apply (simp only: add_assoc[symmetric], simp)
   497 apply (rule join_imp_le)
   498 apply (rule add_le_imp_le_left [of "a"], simp only: add_assoc[symmetric], simp add: meet_join_le)+
   499 apply (rule join_imp_le)
   500 apply (simp_all add: meet_join_le)
   501 done
   502 
   503 lemma is_join_neg_meet: "is_join (% (a::'a::{pordered_ab_group_add, meet_semilorder}) b. - (meet (-a) (-b)))"
   504 apply (auto simp add: is_join_def)
   505 apply (rule_tac c="meet (-a) (-b)" in add_le_imp_le_right, simp, simp add: add_meet_distrib_left meet_join_le)
   506 apply (rule_tac c="meet (-a) (-b)" in add_le_imp_le_right, simp, simp add: add_meet_distrib_left meet_join_le)
   507 apply (subst neg_le_iff_le[symmetric]) 
   508 apply (simp add: meet_imp_le)
   509 done
   510 
   511 lemma is_meet_neg_join: "is_meet (% (a::'a::{pordered_ab_group_add, join_semilorder}) b. - (join (-a) (-b)))"
   512 apply (auto simp add: is_meet_def)
   513 apply (rule_tac c="join (-a) (-b)" in add_le_imp_le_right, simp, simp add: add_join_distrib_left meet_join_le)
   514 apply (rule_tac c="join (-a) (-b)" in add_le_imp_le_right, simp, simp add: add_join_distrib_left meet_join_le)
   515 apply (subst neg_le_iff_le[symmetric]) 
   516 apply (simp add: join_imp_le)
   517 done
   518 
   519 axclass lordered_ab_group \<subseteq> pordered_ab_group_add, lorder
   520 
   521 instance lordered_ab_group_meet \<subseteq> lordered_ab_group
   522 proof 
   523   show "? j. is_join (j::'a\<Rightarrow>'a\<Rightarrow>('a::lordered_ab_group_meet))" by (blast intro: is_join_neg_meet)
   524 qed
   525 
   526 instance lordered_ab_group_join \<subseteq> lordered_ab_group
   527 proof
   528   show "? m. is_meet (m::'a\<Rightarrow>'a\<Rightarrow>('a::lordered_ab_group_join))" by (blast intro: is_meet_neg_join)
   529 qed
   530 
   531 lemma add_join_distrib_right: "(join a b) + (c::'a::lordered_ab_group) = join (a+c) (b+c)"
   532 proof -
   533   have "c + (join a b) = join (c+a) (c+b)" by (simp add: add_join_distrib_left)
   534   thus ?thesis by (simp add: add_commute)
   535 qed
   536 
   537 lemma add_meet_distrib_right: "(meet a b) + (c::'a::lordered_ab_group) = meet (a+c) (b+c)"
   538 proof -
   539   have "c + (meet a b) = meet (c+a) (c+b)" by (simp add: add_meet_distrib_left)
   540   thus ?thesis by (simp add: add_commute)
   541 qed
   542 
   543 lemmas add_meet_join_distribs = add_meet_distrib_right add_meet_distrib_left add_join_distrib_right add_join_distrib_left
   544 
   545 lemma join_eq_neg_meet: "join a (b::'a::lordered_ab_group) = - meet (-a) (-b)"
   546 by (simp add: is_join_unique[OF is_join_join is_join_neg_meet])
   547 
   548 lemma meet_eq_neg_join: "meet a (b::'a::lordered_ab_group) = - join (-a) (-b)"
   549 by (simp add: is_meet_unique[OF is_meet_meet is_meet_neg_join])
   550 
   551 lemma add_eq_meet_join: "a + b = (join a b) + (meet a (b::'a::lordered_ab_group))"
   552 proof -
   553   have "0 = - meet 0 (a-b) + meet (a-b) 0" by (simp add: meet_comm)
   554   hence "0 = join 0 (b-a) + meet (a-b) 0" by (simp add: meet_eq_neg_join)
   555   hence "0 = (-a + join a b) + (meet a b + (-b))"
   556     apply (simp add: add_join_distrib_left add_meet_distrib_right)
   557     by (simp add: diff_minus add_commute)
   558   thus ?thesis
   559     apply (simp add: compare_rls)
   560     apply (subst add_left_cancel[symmetric, of "a+b" "join a b + meet a b" "-a"])
   561     apply (simp only: add_assoc, simp add: add_assoc[symmetric])
   562     done
   563 qed
   564 
   565 subsection {* Positive Part, Negative Part, Absolute Value *}
   566 
   567 constdefs
   568   pprt :: "'a \<Rightarrow> ('a::lordered_ab_group)"
   569   "pprt x == join x 0"
   570   nprt :: "'a \<Rightarrow> ('a::lordered_ab_group)"
   571   "nprt x == meet x 0"
   572 
   573 lemma prts: "a = pprt a + nprt a"
   574 by (simp add: pprt_def nprt_def add_eq_meet_join[symmetric])
   575 
   576 lemma zero_le_pprt[simp]: "0 \<le> pprt a"
   577 by (simp add: pprt_def meet_join_le)
   578 
   579 lemma nprt_le_zero[simp]: "nprt a \<le> 0"
   580 by (simp add: nprt_def meet_join_le)
   581 
   582 lemma le_eq_neg: "(a \<le> -b) = (a + b \<le> (0::_::lordered_ab_group))" (is "?l = ?r")
   583 proof -
   584   have a: "?l \<longrightarrow> ?r"
   585     apply (auto)
   586     apply (rule add_le_imp_le_right[of _ "-b" _])
   587     apply (simp add: add_assoc)
   588     done
   589   have b: "?r \<longrightarrow> ?l"
   590     apply (auto)
   591     apply (rule add_le_imp_le_right[of _ "b" _])
   592     apply (simp)
   593     done
   594   from a b show ?thesis by blast
   595 qed
   596 
   597 lemma pprt_0[simp]: "pprt 0 = 0" by (simp add: pprt_def)
   598 lemma nprt_0[simp]: "nprt 0 = 0" by (simp add: nprt_def)
   599 
   600 lemma pprt_eq_id[simp]: "0 <= x \<Longrightarrow> pprt x = x"
   601   by (simp add: pprt_def le_def_join join_aci)
   602 
   603 lemma nprt_eq_id[simp]: "x <= 0 \<Longrightarrow> nprt x = x"
   604   by (simp add: nprt_def le_def_meet meet_aci)
   605 
   606 lemma pprt_eq_0[simp]: "x <= 0 \<Longrightarrow> pprt x = 0"
   607   by (simp add: pprt_def le_def_join join_aci)
   608 
   609 lemma nprt_eq_0[simp]: "0 <= x \<Longrightarrow> nprt x = 0"
   610   by (simp add: nprt_def le_def_meet meet_aci)
   611 
   612 lemma join_0_imp_0: "join a (-a) = 0 \<Longrightarrow> a = (0::'a::lordered_ab_group)"
   613 proof -
   614   {
   615     fix a::'a
   616     assume hyp: "join a (-a) = 0"
   617     hence "join a (-a) + a = a" by (simp)
   618     hence "join (a+a) 0 = a" by (simp add: add_join_distrib_right) 
   619     hence "join (a+a) 0 <= a" by (simp)
   620     hence "0 <= a" by (blast intro: order_trans meet_join_le)
   621   }
   622   note p = this
   623   assume hyp:"join a (-a) = 0"
   624   hence hyp2:"join (-a) (-(-a)) = 0" by (simp add: join_comm)
   625   from p[OF hyp] p[OF hyp2] show "a = 0" by simp
   626 qed
   627 
   628 lemma meet_0_imp_0: "meet a (-a) = 0 \<Longrightarrow> a = (0::'a::lordered_ab_group)"
   629 apply (simp add: meet_eq_neg_join)
   630 apply (simp add: join_comm)
   631 apply (erule join_0_imp_0)
   632 done
   633 
   634 lemma join_0_eq_0[simp]: "(join a (-a) = 0) = (a = (0::'a::lordered_ab_group))"
   635 by (auto, erule join_0_imp_0)
   636 
   637 lemma meet_0_eq_0[simp]: "(meet a (-a) = 0) = (a = (0::'a::lordered_ab_group))"
   638 by (auto, erule meet_0_imp_0)
   639 
   640 lemma zero_le_double_add_iff_zero_le_single_add[simp]: "(0 \<le> a + a) = (0 \<le> (a::'a::lordered_ab_group))"
   641 proof
   642   assume "0 <= a + a"
   643   hence a:"meet (a+a) 0 = 0" by (simp add: le_def_meet meet_comm)
   644   have "(meet a 0)+(meet a 0) = meet (meet (a+a) 0) a" (is "?l=_") by (simp add: add_meet_join_distribs meet_aci)
   645   hence "?l = 0 + meet a 0" by (simp add: a, simp add: meet_comm)
   646   hence "meet a 0 = 0" by (simp only: add_right_cancel)
   647   then show "0 <= a" by (simp add: le_def_meet meet_comm)    
   648 next  
   649   assume a: "0 <= a"
   650   show "0 <= a + a" by (simp add: add_mono[OF a a, simplified])
   651 qed
   652 
   653 lemma double_add_le_zero_iff_single_add_le_zero[simp]: "(a + a <= 0) = ((a::'a::lordered_ab_group) <= 0)" 
   654 proof -
   655   have "(a + a <= 0) = (0 <= -(a+a))" by (subst le_minus_iff, simp)
   656   moreover have "\<dots> = (a <= 0)" by (simp add: zero_le_double_add_iff_zero_le_single_add)
   657   ultimately show ?thesis by blast
   658 qed
   659 
   660 lemma double_add_less_zero_iff_single_less_zero[simp]: "(a+a<0) = ((a::'a::{pordered_ab_group_add,linorder}) < 0)" (is ?s)
   661 proof cases
   662   assume a: "a < 0"
   663   thus ?s by (simp add:  add_strict_mono[OF a a, simplified])
   664 next
   665   assume "~(a < 0)" 
   666   hence a:"0 <= a" by (simp)
   667   hence "0 <= a+a" by (simp add: add_mono[OF a a, simplified])
   668   hence "~(a+a < 0)" by simp
   669   with a show ?thesis by simp 
   670 qed
   671 
   672 axclass lordered_ab_group_abs \<subseteq> lordered_ab_group
   673   abs_lattice: "abs x = join x (-x)"
   674 
   675 lemma abs_zero[simp]: "abs 0 = (0::'a::lordered_ab_group_abs)"
   676 by (simp add: abs_lattice)
   677 
   678 lemma abs_eq_0[simp]: "(abs a = 0) = (a = (0::'a::lordered_ab_group_abs))"
   679 by (simp add: abs_lattice)
   680 
   681 lemma abs_0_eq[simp]: "(0 = abs a) = (a = (0::'a::lordered_ab_group_abs))"
   682 proof -
   683   have "(0 = abs a) = (abs a = 0)" by (simp only: eq_ac)
   684   thus ?thesis by simp
   685 qed
   686 
   687 lemma neg_meet_eq_join[simp]: "- meet a (b::_::lordered_ab_group) = join (-a) (-b)"
   688 by (simp add: meet_eq_neg_join)
   689 
   690 lemma neg_join_eq_meet[simp]: "- join a (b::_::lordered_ab_group) = meet (-a) (-b)"
   691 by (simp del: neg_meet_eq_join add: join_eq_neg_meet)
   692 
   693 lemma join_eq_if: "join a (-a) = (if a < 0 then -a else (a::'a::{lordered_ab_group, linorder}))"
   694 proof -
   695   note b = add_le_cancel_right[of a a "-a",symmetric,simplified]
   696   have c: "a + a = 0 \<Longrightarrow> -a = a" by (rule add_right_imp_eq[of _ a], simp)
   697   show ?thesis by (auto simp add: join_max max_def b linorder_not_less)
   698 qed
   699 
   700 lemma abs_if_lattice: "\<bar>a\<bar> = (if a < 0 then -a else (a::'a::{lordered_ab_group_abs, linorder}))"
   701 proof -
   702   show ?thesis by (simp add: abs_lattice join_eq_if)
   703 qed
   704 
   705 lemma abs_eq [simp]:
   706   fixes a :: "'a::{lordered_ab_group_abs, linorder}"
   707   shows  "0 \<le> a ==> abs a = a"
   708 by (simp add: abs_if_lattice linorder_not_less [symmetric]) 
   709 
   710 lemma abs_minus_eq [simp]: 
   711   fixes a :: "'a::{lordered_ab_group_abs, linorder}"
   712   shows "a < 0 ==> abs a = -a"
   713 by (simp add: abs_if_lattice linorder_not_less [symmetric])
   714 
   715 lemma abs_ge_zero[simp]: "0 \<le> abs (a::'a::lordered_ab_group_abs)"
   716 proof -
   717   have a:"a <= abs a" and b:"-a <= abs a" by (auto simp add: abs_lattice meet_join_le)
   718   show ?thesis by (rule add_mono[OF a b, simplified])
   719 qed
   720   
   721 lemma abs_le_zero_iff [simp]: "(abs a \<le> (0::'a::lordered_ab_group_abs)) = (a = 0)" 
   722 proof
   723   assume "abs a <= 0"
   724   hence "abs a = 0" by (auto dest: order_antisym)
   725   thus "a = 0" by simp
   726 next
   727   assume "a = 0"
   728   thus "abs a <= 0" by simp
   729 qed
   730 
   731 lemma zero_less_abs_iff [simp]: "(0 < abs a) = (a \<noteq> (0::'a::lordered_ab_group_abs))"
   732 by (simp add: order_less_le)
   733 
   734 lemma abs_not_less_zero [simp]: "~ abs a < (0::'a::lordered_ab_group_abs)"
   735 proof -
   736   have a:"!! x (y::_::order). x <= y \<Longrightarrow> ~(y < x)" by auto
   737   show ?thesis by (simp add: a)
   738 qed
   739 
   740 lemma abs_ge_self: "a \<le> abs (a::'a::lordered_ab_group_abs)"
   741 by (simp add: abs_lattice meet_join_le)
   742 
   743 lemma abs_ge_minus_self: "-a \<le> abs (a::'a::lordered_ab_group_abs)"
   744 by (simp add: abs_lattice meet_join_le)
   745 
   746 lemma le_imp_join_eq: "a \<le> b \<Longrightarrow> join a b = b" 
   747 by (simp add: le_def_join)
   748 
   749 lemma ge_imp_join_eq: "b \<le> a \<Longrightarrow> join a b = a"
   750 by (simp add: le_def_join join_aci)
   751 
   752 lemma le_imp_meet_eq: "a \<le> b \<Longrightarrow> meet a b = a"
   753 by (simp add: le_def_meet)
   754 
   755 lemma ge_imp_meet_eq: "b \<le> a \<Longrightarrow> meet a b = b"
   756 by (simp add: le_def_meet meet_aci)
   757 
   758 lemma abs_prts: "abs (a::_::lordered_ab_group_abs) = pprt a - nprt a"
   759 apply (simp add: pprt_def nprt_def diff_minus)
   760 apply (simp add: add_meet_join_distribs join_aci abs_lattice[symmetric])
   761 apply (subst le_imp_join_eq, auto)
   762 done
   763 
   764 lemma abs_minus_cancel [simp]: "abs (-a) = abs(a::'a::lordered_ab_group_abs)"
   765 by (simp add: abs_lattice join_comm)
   766 
   767 lemma abs_idempotent [simp]: "abs (abs a) = abs (a::'a::lordered_ab_group_abs)"
   768 apply (simp add: abs_lattice[of "abs a"])
   769 apply (subst ge_imp_join_eq)
   770 apply (rule order_trans[of _ 0])
   771 by auto
   772 
   773 lemma abs_minus_commute: 
   774   fixes a :: "'a::lordered_ab_group_abs"
   775   shows "abs (a-b) = abs(b-a)"
   776 proof -
   777   have "abs (a-b) = abs (- (a-b))" by (simp only: abs_minus_cancel)
   778   also have "... = abs(b-a)" by simp
   779   finally show ?thesis .
   780 qed
   781 
   782 lemma zero_le_iff_zero_nprt: "(0 \<le> a) = (nprt a = 0)"
   783 by (simp add: le_def_meet nprt_def meet_comm)
   784 
   785 lemma le_zero_iff_zero_pprt: "(a \<le> 0) = (pprt a = 0)"
   786 by (simp add: le_def_join pprt_def join_comm)
   787 
   788 lemma le_zero_iff_pprt_id: "(0 \<le> a) = (pprt a = a)"
   789 by (simp add: le_def_join pprt_def join_comm)
   790 
   791 lemma zero_le_iff_nprt_id: "(a \<le> 0) = (nprt a = a)"
   792 by (simp add: le_def_meet nprt_def meet_comm)
   793 
   794 lemma pprt_mono[simp]: "(a::_::lordered_ab_group) <= b \<Longrightarrow> pprt a <= pprt b"
   795   by (simp add: le_def_join pprt_def join_aci)
   796 
   797 lemma nprt_mono[simp]: "(a::_::lordered_ab_group) <= b \<Longrightarrow> nprt a <= nprt b"
   798   by (simp add: le_def_meet nprt_def meet_aci)
   799 
   800 lemma iff2imp: "(A=B) \<Longrightarrow> (A \<Longrightarrow> B)"
   801 by (simp)
   802 
   803 lemma imp_abs_id: "0 \<le> a \<Longrightarrow> abs a = (a::'a::lordered_ab_group_abs)"
   804 by (simp add: iff2imp[OF zero_le_iff_zero_nprt] iff2imp[OF le_zero_iff_pprt_id] abs_prts)
   805 
   806 lemma imp_abs_neg_id: "a \<le> 0 \<Longrightarrow> abs a = -(a::'a::lordered_ab_group_abs)"
   807 by (simp add: iff2imp[OF le_zero_iff_zero_pprt] iff2imp[OF zero_le_iff_nprt_id] abs_prts)
   808 
   809 lemma abs_leI: "[|a \<le> b; -a \<le> b|] ==> abs a \<le> (b::'a::lordered_ab_group_abs)"
   810 by (simp add: abs_lattice join_imp_le)
   811 
   812 lemma le_minus_self_iff: "(a \<le> -a) = (a \<le> (0::'a::lordered_ab_group))"
   813 proof -
   814   from add_le_cancel_left[of "-a" "a+a" "0"] have "(a <= -a) = (a+a <= 0)" 
   815     by (simp add: add_assoc[symmetric])
   816   thus ?thesis by simp
   817 qed
   818 
   819 lemma minus_le_self_iff: "(-a \<le> a) = (0 \<le> (a::'a::lordered_ab_group))"
   820 proof -
   821   from add_le_cancel_left[of "-a" "0" "a+a"] have "(-a <= a) = (0 <= a+a)" 
   822     by (simp add: add_assoc[symmetric])
   823   thus ?thesis by simp
   824 qed
   825 
   826 lemma abs_le_D1: "abs a \<le> b ==> a \<le> (b::'a::lordered_ab_group_abs)"
   827 by (insert abs_ge_self, blast intro: order_trans)
   828 
   829 lemma abs_le_D2: "abs a \<le> b ==> -a \<le> (b::'a::lordered_ab_group_abs)"
   830 by (insert abs_le_D1 [of "-a"], simp)
   831 
   832 lemma abs_le_iff: "(abs a \<le> b) = (a \<le> b & -a \<le> (b::'a::lordered_ab_group_abs))"
   833 by (blast intro: abs_leI dest: abs_le_D1 abs_le_D2)
   834 
   835 lemma abs_triangle_ineq: "abs(a+b) \<le> abs a + abs(b::'a::lordered_ab_group_abs)"
   836 proof -
   837   have g:"abs a + abs b = join (a+b) (join (-a-b) (join (-a+b) (a + (-b))))" (is "_=join ?m ?n")
   838     apply (simp add: abs_lattice add_meet_join_distribs join_aci)
   839     by (simp only: diff_minus)
   840   have a:"a+b <= join ?m ?n" by (simp add: meet_join_le)
   841   have b:"-a-b <= ?n" by (simp add: meet_join_le) 
   842   have c:"?n <= join ?m ?n" by (simp add: meet_join_le)
   843   from b c have d: "-a-b <= join ?m ?n" by simp
   844   have e:"-a-b = -(a+b)" by (simp add: diff_minus)
   845   from a d e have "abs(a+b) <= join ?m ?n" 
   846     by (drule_tac abs_leI, auto)
   847   with g[symmetric] show ?thesis by simp
   848 qed
   849 
   850 lemma abs_diff_triangle_ineq:
   851      "\<bar>(a::'a::lordered_ab_group_abs) + b - (c+d)\<bar> \<le> \<bar>a-c\<bar> + \<bar>b-d\<bar>"
   852 proof -
   853   have "\<bar>a + b - (c+d)\<bar> = \<bar>(a-c) + (b-d)\<bar>" by (simp add: diff_minus add_ac)
   854   also have "... \<le> \<bar>a-c\<bar> + \<bar>b-d\<bar>" by (rule abs_triangle_ineq)
   855   finally show ?thesis .
   856 qed
   857 
   858 lemma abs_add_abs[simp]:
   859 fixes a:: "'a::{lordered_ab_group_abs}"
   860 shows "abs(abs a + abs b) = abs a + abs b" (is "?L = ?R")
   861 proof (rule order_antisym)
   862   show "?L \<ge> ?R" by(rule abs_ge_self)
   863 next
   864   have "?L \<le> \<bar>\<bar>a\<bar>\<bar> + \<bar>\<bar>b\<bar>\<bar>" by(rule abs_triangle_ineq)
   865   also have "\<dots> = ?R" by simp
   866   finally show "?L \<le> ?R" .
   867 qed
   868 
   869 text {* Needed for abelian cancellation simprocs: *}
   870 
   871 lemma add_cancel_21: "((x::'a::ab_group_add) + (y + z) = y + u) = (x + z = u)"
   872 apply (subst add_left_commute)
   873 apply (subst add_left_cancel)
   874 apply simp
   875 done
   876 
   877 lemma add_cancel_end: "(x + (y + z) = y) = (x = - (z::'a::ab_group_add))"
   878 apply (subst add_cancel_21[of _ _ _ 0, simplified])
   879 apply (simp add: add_right_cancel[symmetric, of "x" "-z" "z", simplified])
   880 done
   881 
   882 lemma less_eqI: "(x::'a::pordered_ab_group_add) - y = x' - y' \<Longrightarrow> (x < y) = (x' < y')"
   883 by (simp add: less_iff_diff_less_0[of x y] less_iff_diff_less_0[of x' y'])
   884 
   885 lemma le_eqI: "(x::'a::pordered_ab_group_add) - y = x' - y' \<Longrightarrow> (y <= x) = (y' <= x')"
   886 apply (simp add: le_iff_diff_le_0[of y x] le_iff_diff_le_0[of  y' x'])
   887 apply (simp add: neg_le_iff_le[symmetric, of "y-x" 0] neg_le_iff_le[symmetric, of "y'-x'" 0])
   888 done
   889 
   890 lemma eq_eqI: "(x::'a::ab_group_add) - y = x' - y' \<Longrightarrow> (x = y) = (x' = y')"
   891 by (simp add: eq_iff_diff_eq_0[of x y] eq_iff_diff_eq_0[of x' y'])
   892 
   893 lemma diff_def: "(x::'a::ab_group_add) - y == x + (-y)"
   894 by (simp add: diff_minus)
   895 
   896 lemma add_minus_cancel: "(a::'a::ab_group_add) + (-a + b) = b"
   897 by (simp add: add_assoc[symmetric])
   898 
   899 lemma minus_add_cancel: "-(a::'a::ab_group_add) + (a + b) = b"
   900 by (simp add: add_assoc[symmetric])
   901 
   902 lemma  le_add_right_mono: 
   903   assumes 
   904   "a <= b + (c::'a::pordered_ab_group_add)"
   905   "c <= d"    
   906   shows "a <= b + d"
   907   apply (rule_tac order_trans[where y = "b+c"])
   908   apply (simp_all add: prems)
   909   done
   910 
   911 lemmas group_eq_simps =
   912   mult_ac
   913   add_ac
   914   add_diff_eq diff_add_eq diff_diff_eq diff_diff_eq2
   915   diff_eq_eq eq_diff_eq
   916 
   917 lemma estimate_by_abs:
   918 "a + b <= (c::'a::lordered_ab_group_abs) \<Longrightarrow> a <= c + abs b" 
   919 proof -
   920   assume 1: "a+b <= c"
   921   have 2: "a <= c+(-b)"
   922     apply (insert 1)
   923     apply (drule_tac add_right_mono[where c="-b"])
   924     apply (simp add: group_eq_simps)
   925     done
   926   have 3: "(-b) <= abs b" by (rule abs_ge_minus_self)
   927   show ?thesis by (rule le_add_right_mono[OF 2 3])
   928 qed
   929 
   930 lemma abs_of_ge_0: "0 <= (y::'a::lordered_ab_group_abs) \<Longrightarrow> abs y = y"
   931 proof -
   932   assume 1:"0 <= y"
   933   have 2:"-y <= 0" by (simp add: 1)
   934   from 1 2 have 3:"-y <= y" by (simp only:)
   935   show ?thesis by (simp add: abs_lattice ge_imp_join_eq[OF 3])
   936 qed
   937 
   938 ML {*
   939 val add_zero_left = thm"add_0";
   940 val add_zero_right = thm"add_0_right";
   941 *}
   942 
   943 ML {*
   944 val add_assoc = thm "add_assoc";
   945 val add_commute = thm "add_commute";
   946 val add_left_commute = thm "add_left_commute";
   947 val add_ac = thms "add_ac";
   948 val mult_assoc = thm "mult_assoc";
   949 val mult_commute = thm "mult_commute";
   950 val mult_left_commute = thm "mult_left_commute";
   951 val mult_ac = thms "mult_ac";
   952 val add_0 = thm "add_0";
   953 val mult_1_left = thm "mult_1_left";
   954 val mult_1_right = thm "mult_1_right";
   955 val mult_1 = thm "mult_1";
   956 val add_left_imp_eq = thm "add_left_imp_eq";
   957 val add_right_imp_eq = thm "add_right_imp_eq";
   958 val add_imp_eq = thm "add_imp_eq";
   959 val left_minus = thm "left_minus";
   960 val diff_minus = thm "diff_minus";
   961 val add_0_right = thm "add_0_right";
   962 val add_left_cancel = thm "add_left_cancel";
   963 val add_right_cancel = thm "add_right_cancel";
   964 val right_minus = thm "right_minus";
   965 val right_minus_eq = thm "right_minus_eq";
   966 val minus_minus = thm "minus_minus";
   967 val equals_zero_I = thm "equals_zero_I";
   968 val minus_zero = thm "minus_zero";
   969 val diff_self = thm "diff_self";
   970 val diff_0 = thm "diff_0";
   971 val diff_0_right = thm "diff_0_right";
   972 val diff_minus_eq_add = thm "diff_minus_eq_add";
   973 val neg_equal_iff_equal = thm "neg_equal_iff_equal";
   974 val neg_equal_0_iff_equal = thm "neg_equal_0_iff_equal";
   975 val neg_0_equal_iff_equal = thm "neg_0_equal_iff_equal";
   976 val equation_minus_iff = thm "equation_minus_iff";
   977 val minus_equation_iff = thm "minus_equation_iff";
   978 val minus_add_distrib = thm "minus_add_distrib";
   979 val minus_diff_eq = thm "minus_diff_eq";
   980 val add_left_mono = thm "add_left_mono";
   981 val add_le_imp_le_left = thm "add_le_imp_le_left";
   982 val add_right_mono = thm "add_right_mono";
   983 val add_mono = thm "add_mono";
   984 val add_strict_left_mono = thm "add_strict_left_mono";
   985 val add_strict_right_mono = thm "add_strict_right_mono";
   986 val add_strict_mono = thm "add_strict_mono";
   987 val add_less_le_mono = thm "add_less_le_mono";
   988 val add_le_less_mono = thm "add_le_less_mono";
   989 val add_less_imp_less_left = thm "add_less_imp_less_left";
   990 val add_less_imp_less_right = thm "add_less_imp_less_right";
   991 val add_less_cancel_left = thm "add_less_cancel_left";
   992 val add_less_cancel_right = thm "add_less_cancel_right";
   993 val add_le_cancel_left = thm "add_le_cancel_left";
   994 val add_le_cancel_right = thm "add_le_cancel_right";
   995 val add_le_imp_le_right = thm "add_le_imp_le_right";
   996 val add_increasing = thm "add_increasing";
   997 val le_imp_neg_le = thm "le_imp_neg_le";
   998 val neg_le_iff_le = thm "neg_le_iff_le";
   999 val neg_le_0_iff_le = thm "neg_le_0_iff_le";
  1000 val neg_0_le_iff_le = thm "neg_0_le_iff_le";
  1001 val neg_less_iff_less = thm "neg_less_iff_less";
  1002 val neg_less_0_iff_less = thm "neg_less_0_iff_less";
  1003 val neg_0_less_iff_less = thm "neg_0_less_iff_less";
  1004 val less_minus_iff = thm "less_minus_iff";
  1005 val minus_less_iff = thm "minus_less_iff";
  1006 val le_minus_iff = thm "le_minus_iff";
  1007 val minus_le_iff = thm "minus_le_iff";
  1008 val add_diff_eq = thm "add_diff_eq";
  1009 val diff_add_eq = thm "diff_add_eq";
  1010 val diff_eq_eq = thm "diff_eq_eq";
  1011 val eq_diff_eq = thm "eq_diff_eq";
  1012 val diff_diff_eq = thm "diff_diff_eq";
  1013 val diff_diff_eq2 = thm "diff_diff_eq2";
  1014 val diff_add_cancel = thm "diff_add_cancel";
  1015 val add_diff_cancel = thm "add_diff_cancel";
  1016 val less_iff_diff_less_0 = thm "less_iff_diff_less_0";
  1017 val diff_less_eq = thm "diff_less_eq";
  1018 val less_diff_eq = thm "less_diff_eq";
  1019 val diff_le_eq = thm "diff_le_eq";
  1020 val le_diff_eq = thm "le_diff_eq";
  1021 val compare_rls = thms "compare_rls";
  1022 val eq_iff_diff_eq_0 = thm "eq_iff_diff_eq_0";
  1023 val le_iff_diff_le_0 = thm "le_iff_diff_le_0";
  1024 val add_meet_distrib_left = thm "add_meet_distrib_left";
  1025 val add_join_distrib_left = thm "add_join_distrib_left";
  1026 val is_join_neg_meet = thm "is_join_neg_meet";
  1027 val is_meet_neg_join = thm "is_meet_neg_join";
  1028 val add_join_distrib_right = thm "add_join_distrib_right";
  1029 val add_meet_distrib_right = thm "add_meet_distrib_right";
  1030 val add_meet_join_distribs = thms "add_meet_join_distribs";
  1031 val join_eq_neg_meet = thm "join_eq_neg_meet";
  1032 val meet_eq_neg_join = thm "meet_eq_neg_join";
  1033 val add_eq_meet_join = thm "add_eq_meet_join";
  1034 val prts = thm "prts";
  1035 val zero_le_pprt = thm "zero_le_pprt";
  1036 val nprt_le_zero = thm "nprt_le_zero";
  1037 val le_eq_neg = thm "le_eq_neg";
  1038 val join_0_imp_0 = thm "join_0_imp_0";
  1039 val meet_0_imp_0 = thm "meet_0_imp_0";
  1040 val join_0_eq_0 = thm "join_0_eq_0";
  1041 val meet_0_eq_0 = thm "meet_0_eq_0";
  1042 val zero_le_double_add_iff_zero_le_single_add = thm "zero_le_double_add_iff_zero_le_single_add";
  1043 val double_add_le_zero_iff_single_add_le_zero = thm "double_add_le_zero_iff_single_add_le_zero";
  1044 val double_add_less_zero_iff_single_less_zero = thm "double_add_less_zero_iff_single_less_zero";
  1045 val abs_lattice = thm "abs_lattice";
  1046 val abs_zero = thm "abs_zero";
  1047 val abs_eq_0 = thm "abs_eq_0";
  1048 val abs_0_eq = thm "abs_0_eq";
  1049 val neg_meet_eq_join = thm "neg_meet_eq_join";
  1050 val neg_join_eq_meet = thm "neg_join_eq_meet";
  1051 val join_eq_if = thm "join_eq_if";
  1052 val abs_if_lattice = thm "abs_if_lattice";
  1053 val abs_ge_zero = thm "abs_ge_zero";
  1054 val abs_le_zero_iff = thm "abs_le_zero_iff";
  1055 val zero_less_abs_iff = thm "zero_less_abs_iff";
  1056 val abs_not_less_zero = thm "abs_not_less_zero";
  1057 val abs_ge_self = thm "abs_ge_self";
  1058 val abs_ge_minus_self = thm "abs_ge_minus_self";
  1059 val le_imp_join_eq = thm "le_imp_join_eq";
  1060 val ge_imp_join_eq = thm "ge_imp_join_eq";
  1061 val le_imp_meet_eq = thm "le_imp_meet_eq";
  1062 val ge_imp_meet_eq = thm "ge_imp_meet_eq";
  1063 val abs_prts = thm "abs_prts";
  1064 val abs_minus_cancel = thm "abs_minus_cancel";
  1065 val abs_idempotent = thm "abs_idempotent";
  1066 val zero_le_iff_zero_nprt = thm "zero_le_iff_zero_nprt";
  1067 val le_zero_iff_zero_pprt = thm "le_zero_iff_zero_pprt";
  1068 val le_zero_iff_pprt_id = thm "le_zero_iff_pprt_id";
  1069 val zero_le_iff_nprt_id = thm "zero_le_iff_nprt_id";
  1070 val iff2imp = thm "iff2imp";
  1071 val imp_abs_id = thm "imp_abs_id";
  1072 val imp_abs_neg_id = thm "imp_abs_neg_id";
  1073 val abs_leI = thm "abs_leI";
  1074 val le_minus_self_iff = thm "le_minus_self_iff";
  1075 val minus_le_self_iff = thm "minus_le_self_iff";
  1076 val abs_le_D1 = thm "abs_le_D1";
  1077 val abs_le_D2 = thm "abs_le_D2";
  1078 val abs_le_iff = thm "abs_le_iff";
  1079 val abs_triangle_ineq = thm "abs_triangle_ineq";
  1080 val abs_diff_triangle_ineq = thm "abs_diff_triangle_ineq";
  1081 *}
  1082 
  1083 end