src/HOL/Algebra/UnivPoly.thy
 author ballarin Mon Aug 02 09:44:46 2004 +0200 (2004-08-02) changeset 15095 63f5f4c265dd parent 15076 4b3d280ef06a child 15481 fc075ae929e4 permissions -rw-r--r--
Theories now take advantage of recent syntax improvements with (structure).
```     1 (*
```
```     2   Title:     HOL/Algebra/UnivPoly.thy
```
```     3   Id:        \$Id\$
```
```     4   Author:    Clemens Ballarin, started 9 December 1996
```
```     5   Copyright: Clemens Ballarin
```
```     6 *)
```
```     7
```
```     8 header {* Univariate Polynomials *}
```
```     9
```
```    10 theory UnivPoly = Module:
```
```    11
```
```    12 text {*
```
```    13   Polynomials are formalised as modules with additional operations for
```
```    14   extracting coefficients from polynomials and for obtaining monomials
```
```    15   from coefficients and exponents (record @{text "up_ring"}).  The
```
```    16   carrier set is a set of bounded functions from Nat to the
```
```    17   coefficient domain.  Bounded means that these functions return zero
```
```    18   above a certain bound (the degree).  There is a chapter on the
```
```    19   formalisation of polynomials in the PhD thesis \cite{Ballarin:1999},
```
```    20   which was implemented with axiomatic type classes.  This was later
```
```    21   ported to Locales.
```
```    22 *}
```
```    23
```
```    24
```
```    25 subsection {* The Constructor for Univariate Polynomials *}
```
```    26
```
```    27 text {*
```
```    28   Functions with finite support.
```
```    29 *}
```
```    30
```
```    31 locale bound =
```
```    32   fixes z :: 'a
```
```    33     and n :: nat
```
```    34     and f :: "nat => 'a"
```
```    35   assumes bound: "!!m. n < m \<Longrightarrow> f m = z"
```
```    36
```
```    37 declare bound.intro [intro!]
```
```    38   and bound.bound [dest]
```
```    39
```
```    40 lemma bound_below:
```
```    41   assumes bound: "bound z m f" and nonzero: "f n \<noteq> z" shows "n \<le> m"
```
```    42 proof (rule classical)
```
```    43   assume "~ ?thesis"
```
```    44   then have "m < n" by arith
```
```    45   with bound have "f n = z" ..
```
```    46   with nonzero show ?thesis by contradiction
```
```    47 qed
```
```    48
```
```    49 record ('a, 'p) up_ring = "('a, 'p) module" +
```
```    50   monom :: "['a, nat] => 'p"
```
```    51   coeff :: "['p, nat] => 'a"
```
```    52
```
```    53 constdefs (structure R)
```
```    54   up :: "('a, 'm) ring_scheme => (nat => 'a) set"
```
```    55   "up R == {f. f \<in> UNIV -> carrier R & (EX n. bound \<zero> n f)}"
```
```    56   UP :: "('a, 'm) ring_scheme => ('a, nat => 'a) up_ring"
```
```    57   "UP R == (|
```
```    58     carrier = up R,
```
```    59     mult = (%p:up R. %q:up R. %n. \<Oplus>i \<in> {..n}. p i \<otimes> q (n-i)),
```
```    60     one = (%i. if i=0 then \<one> else \<zero>),
```
```    61     zero = (%i. \<zero>),
```
```    62     add = (%p:up R. %q:up R. %i. p i \<oplus> q i),
```
```    63     smult = (%a:carrier R. %p:up R. %i. a \<otimes> p i),
```
```    64     monom = (%a:carrier R. %n i. if i=n then a else \<zero>),
```
```    65     coeff = (%p:up R. %n. p n) |)"
```
```    66
```
```    67 text {*
```
```    68   Properties of the set of polynomials @{term up}.
```
```    69 *}
```
```    70
```
```    71 lemma mem_upI [intro]:
```
```    72   "[| !!n. f n \<in> carrier R; EX n. bound (zero R) n f |] ==> f \<in> up R"
```
```    73   by (simp add: up_def Pi_def)
```
```    74
```
```    75 lemma mem_upD [dest]:
```
```    76   "f \<in> up R ==> f n \<in> carrier R"
```
```    77   by (simp add: up_def Pi_def)
```
```    78
```
```    79 lemma (in cring) bound_upD [dest]:
```
```    80   "f \<in> up R ==> EX n. bound \<zero> n f"
```
```    81   by (simp add: up_def)
```
```    82
```
```    83 lemma (in cring) up_one_closed:
```
```    84    "(%n. if n = 0 then \<one> else \<zero>) \<in> up R"
```
```    85   using up_def by force
```
```    86
```
```    87 lemma (in cring) up_smult_closed:
```
```    88   "[| a \<in> carrier R; p \<in> up R |] ==> (%i. a \<otimes> p i) \<in> up R"
```
```    89   by force
```
```    90
```
```    91 lemma (in cring) up_add_closed:
```
```    92   "[| p \<in> up R; q \<in> up R |] ==> (%i. p i \<oplus> q i) \<in> up R"
```
```    93 proof
```
```    94   fix n
```
```    95   assume "p \<in> up R" and "q \<in> up R"
```
```    96   then show "p n \<oplus> q n \<in> carrier R"
```
```    97     by auto
```
```    98 next
```
```    99   assume UP: "p \<in> up R" "q \<in> up R"
```
```   100   show "EX n. bound \<zero> n (%i. p i \<oplus> q i)"
```
```   101   proof -
```
```   102     from UP obtain n where boundn: "bound \<zero> n p" by fast
```
```   103     from UP obtain m where boundm: "bound \<zero> m q" by fast
```
```   104     have "bound \<zero> (max n m) (%i. p i \<oplus> q i)"
```
```   105     proof
```
```   106       fix i
```
```   107       assume "max n m < i"
```
```   108       with boundn and boundm and UP show "p i \<oplus> q i = \<zero>" by fastsimp
```
```   109     qed
```
```   110     then show ?thesis ..
```
```   111   qed
```
```   112 qed
```
```   113
```
```   114 lemma (in cring) up_a_inv_closed:
```
```   115   "p \<in> up R ==> (%i. \<ominus> (p i)) \<in> up R"
```
```   116 proof
```
```   117   assume R: "p \<in> up R"
```
```   118   then obtain n where "bound \<zero> n p" by auto
```
```   119   then have "bound \<zero> n (%i. \<ominus> p i)" by auto
```
```   120   then show "EX n. bound \<zero> n (%i. \<ominus> p i)" by auto
```
```   121 qed auto
```
```   122
```
```   123 lemma (in cring) up_mult_closed:
```
```   124   "[| p \<in> up R; q \<in> up R |] ==>
```
```   125   (%n. \<Oplus>i \<in> {..n}. p i \<otimes> q (n-i)) \<in> up R"
```
```   126 proof
```
```   127   fix n
```
```   128   assume "p \<in> up R" "q \<in> up R"
```
```   129   then show "(\<Oplus>i \<in> {..n}. p i \<otimes> q (n-i)) \<in> carrier R"
```
```   130     by (simp add: mem_upD  funcsetI)
```
```   131 next
```
```   132   assume UP: "p \<in> up R" "q \<in> up R"
```
```   133   show "EX n. bound \<zero> n (%n. \<Oplus>i \<in> {..n}. p i \<otimes> q (n-i))"
```
```   134   proof -
```
```   135     from UP obtain n where boundn: "bound \<zero> n p" by fast
```
```   136     from UP obtain m where boundm: "bound \<zero> m q" by fast
```
```   137     have "bound \<zero> (n + m) (%n. \<Oplus>i \<in> {..n}. p i \<otimes> q (n - i))"
```
```   138     proof
```
```   139       fix k assume bound: "n + m < k"
```
```   140       {
```
```   141         fix i
```
```   142         have "p i \<otimes> q (k-i) = \<zero>"
```
```   143         proof (cases "n < i")
```
```   144           case True
```
```   145           with boundn have "p i = \<zero>" by auto
```
```   146           moreover from UP have "q (k-i) \<in> carrier R" by auto
```
```   147           ultimately show ?thesis by simp
```
```   148         next
```
```   149           case False
```
```   150           with bound have "m < k-i" by arith
```
```   151           with boundm have "q (k-i) = \<zero>" by auto
```
```   152           moreover from UP have "p i \<in> carrier R" by auto
```
```   153           ultimately show ?thesis by simp
```
```   154         qed
```
```   155       }
```
```   156       then show "(\<Oplus>i \<in> {..k}. p i \<otimes> q (k-i)) = \<zero>"
```
```   157         by (simp add: Pi_def)
```
```   158     qed
```
```   159     then show ?thesis by fast
```
```   160   qed
```
```   161 qed
```
```   162
```
```   163
```
```   164 subsection {* Effect of operations on coefficients *}
```
```   165
```
```   166 locale UP = struct R + struct P +
```
```   167   defines P_def: "P == UP R"
```
```   168
```
```   169 locale UP_cring = UP + cring R
```
```   170
```
```   171 locale UP_domain = UP_cring + "domain" R
```
```   172
```
```   173 text {*
```
```   174   Temporarily declare @{thm [locale=UP] P_def} as simp rule.
```
```   175 *}
```
```   176
```
```   177 declare (in UP) P_def [simp]
```
```   178
```
```   179 lemma (in UP_cring) coeff_monom [simp]:
```
```   180   "a \<in> carrier R ==>
```
```   181   coeff P (monom P a m) n = (if m=n then a else \<zero>)"
```
```   182 proof -
```
```   183   assume R: "a \<in> carrier R"
```
```   184   then have "(%n. if n = m then a else \<zero>) \<in> up R"
```
```   185     using up_def by force
```
```   186   with R show ?thesis by (simp add: UP_def)
```
```   187 qed
```
```   188
```
```   189 lemma (in UP_cring) coeff_zero [simp]:
```
```   190   "coeff P \<zero>\<^bsub>P\<^esub> n = \<zero>"
```
```   191   by (auto simp add: UP_def)
```
```   192
```
```   193 lemma (in UP_cring) coeff_one [simp]:
```
```   194   "coeff P \<one>\<^bsub>P\<^esub> n = (if n=0 then \<one> else \<zero>)"
```
```   195   using up_one_closed by (simp add: UP_def)
```
```   196
```
```   197 lemma (in UP_cring) coeff_smult [simp]:
```
```   198   "[| a \<in> carrier R; p \<in> carrier P |] ==>
```
```   199   coeff P (a \<odot>\<^bsub>P\<^esub> p) n = a \<otimes> coeff P p n"
```
```   200   by (simp add: UP_def up_smult_closed)
```
```   201
```
```   202 lemma (in UP_cring) coeff_add [simp]:
```
```   203   "[| p \<in> carrier P; q \<in> carrier P |] ==>
```
```   204   coeff P (p \<oplus>\<^bsub>P\<^esub> q) n = coeff P p n \<oplus> coeff P q n"
```
```   205   by (simp add: UP_def up_add_closed)
```
```   206
```
```   207 lemma (in UP_cring) coeff_mult [simp]:
```
```   208   "[| p \<in> carrier P; q \<in> carrier P |] ==>
```
```   209   coeff P (p \<otimes>\<^bsub>P\<^esub> q) n = (\<Oplus>i \<in> {..n}. coeff P p i \<otimes> coeff P q (n-i))"
```
```   210   by (simp add: UP_def up_mult_closed)
```
```   211
```
```   212 lemma (in UP) up_eqI:
```
```   213   assumes prem: "!!n. coeff P p n = coeff P q n"
```
```   214     and R: "p \<in> carrier P" "q \<in> carrier P"
```
```   215   shows "p = q"
```
```   216 proof
```
```   217   fix x
```
```   218   from prem and R show "p x = q x" by (simp add: UP_def)
```
```   219 qed
```
```   220
```
```   221 subsection {* Polynomials form a commutative ring. *}
```
```   222
```
```   223 text {* Operations are closed over @{term P}. *}
```
```   224
```
```   225 lemma (in UP_cring) UP_mult_closed [simp]:
```
```   226   "[| p \<in> carrier P; q \<in> carrier P |] ==> p \<otimes>\<^bsub>P\<^esub> q \<in> carrier P"
```
```   227   by (simp add: UP_def up_mult_closed)
```
```   228
```
```   229 lemma (in UP_cring) UP_one_closed [simp]:
```
```   230   "\<one>\<^bsub>P\<^esub> \<in> carrier P"
```
```   231   by (simp add: UP_def up_one_closed)
```
```   232
```
```   233 lemma (in UP_cring) UP_zero_closed [intro, simp]:
```
```   234   "\<zero>\<^bsub>P\<^esub> \<in> carrier P"
```
```   235   by (auto simp add: UP_def)
```
```   236
```
```   237 lemma (in UP_cring) UP_a_closed [intro, simp]:
```
```   238   "[| p \<in> carrier P; q \<in> carrier P |] ==> p \<oplus>\<^bsub>P\<^esub> q \<in> carrier P"
```
```   239   by (simp add: UP_def up_add_closed)
```
```   240
```
```   241 lemma (in UP_cring) monom_closed [simp]:
```
```   242   "a \<in> carrier R ==> monom P a n \<in> carrier P"
```
```   243   by (auto simp add: UP_def up_def Pi_def)
```
```   244
```
```   245 lemma (in UP_cring) UP_smult_closed [simp]:
```
```   246   "[| a \<in> carrier R; p \<in> carrier P |] ==> a \<odot>\<^bsub>P\<^esub> p \<in> carrier P"
```
```   247   by (simp add: UP_def up_smult_closed)
```
```   248
```
```   249 lemma (in UP) coeff_closed [simp]:
```
```   250   "p \<in> carrier P ==> coeff P p n \<in> carrier R"
```
```   251   by (auto simp add: UP_def)
```
```   252
```
```   253 declare (in UP) P_def [simp del]
```
```   254
```
```   255 text {* Algebraic ring properties *}
```
```   256
```
```   257 lemma (in UP_cring) UP_a_assoc:
```
```   258   assumes R: "p \<in> carrier P" "q \<in> carrier P" "r \<in> carrier P"
```
```   259   shows "(p \<oplus>\<^bsub>P\<^esub> q) \<oplus>\<^bsub>P\<^esub> r = p \<oplus>\<^bsub>P\<^esub> (q \<oplus>\<^bsub>P\<^esub> r)"
```
```   260   by (rule up_eqI, simp add: a_assoc R, simp_all add: R)
```
```   261
```
```   262 lemma (in UP_cring) UP_l_zero [simp]:
```
```   263   assumes R: "p \<in> carrier P"
```
```   264   shows "\<zero>\<^bsub>P\<^esub> \<oplus>\<^bsub>P\<^esub> p = p"
```
```   265   by (rule up_eqI, simp_all add: R)
```
```   266
```
```   267 lemma (in UP_cring) UP_l_neg_ex:
```
```   268   assumes R: "p \<in> carrier P"
```
```   269   shows "EX q : carrier P. q \<oplus>\<^bsub>P\<^esub> p = \<zero>\<^bsub>P\<^esub>"
```
```   270 proof -
```
```   271   let ?q = "%i. \<ominus> (p i)"
```
```   272   from R have closed: "?q \<in> carrier P"
```
```   273     by (simp add: UP_def P_def up_a_inv_closed)
```
```   274   from R have coeff: "!!n. coeff P ?q n = \<ominus> (coeff P p n)"
```
```   275     by (simp add: UP_def P_def up_a_inv_closed)
```
```   276   show ?thesis
```
```   277   proof
```
```   278     show "?q \<oplus>\<^bsub>P\<^esub> p = \<zero>\<^bsub>P\<^esub>"
```
```   279       by (auto intro!: up_eqI simp add: R closed coeff R.l_neg)
```
```   280   qed (rule closed)
```
```   281 qed
```
```   282
```
```   283 lemma (in UP_cring) UP_a_comm:
```
```   284   assumes R: "p \<in> carrier P" "q \<in> carrier P"
```
```   285   shows "p \<oplus>\<^bsub>P\<^esub> q = q \<oplus>\<^bsub>P\<^esub> p"
```
```   286   by (rule up_eqI, simp add: a_comm R, simp_all add: R)
```
```   287
```
```   288 ML_setup {*
```
```   289   simpset_ref() := simpset() setsubgoaler asm_full_simp_tac;
```
```   290 *}
```
```   291
```
```   292 lemma (in UP_cring) UP_m_assoc:
```
```   293   assumes R: "p \<in> carrier P" "q \<in> carrier P" "r \<in> carrier P"
```
```   294   shows "(p \<otimes>\<^bsub>P\<^esub> q) \<otimes>\<^bsub>P\<^esub> r = p \<otimes>\<^bsub>P\<^esub> (q \<otimes>\<^bsub>P\<^esub> r)"
```
```   295 proof (rule up_eqI)
```
```   296   fix n
```
```   297   {
```
```   298     fix k and a b c :: "nat=>'a"
```
```   299     assume R: "a \<in> UNIV -> carrier R" "b \<in> UNIV -> carrier R"
```
```   300       "c \<in> UNIV -> carrier R"
```
```   301     then have "k <= n ==>
```
```   302       (\<Oplus>j \<in> {..k}. (\<Oplus>i \<in> {..j}. a i \<otimes> b (j-i)) \<otimes> c (n-j)) =
```
```   303       (\<Oplus>j \<in> {..k}. a j \<otimes> (\<Oplus>i \<in> {..k-j}. b i \<otimes> c (n-j-i)))"
```
```   304       (concl is "?eq k")
```
```   305     proof (induct k)
```
```   306       case 0 then show ?case by (simp add: Pi_def m_assoc)
```
```   307     next
```
```   308       case (Suc k)
```
```   309       then have "k <= n" by arith
```
```   310       then have "?eq k" by (rule Suc)
```
```   311       with R show ?case
```
```   312         by (simp cong: finsum_cong
```
```   313              add: Suc_diff_le Pi_def l_distr r_distr m_assoc)
```
```   314           (simp cong: finsum_cong add: Pi_def a_ac finsum_ldistr m_assoc)
```
```   315     qed
```
```   316   }
```
```   317   with R show "coeff P ((p \<otimes>\<^bsub>P\<^esub> q) \<otimes>\<^bsub>P\<^esub> r) n = coeff P (p \<otimes>\<^bsub>P\<^esub> (q \<otimes>\<^bsub>P\<^esub> r)) n"
```
```   318     by (simp add: Pi_def)
```
```   319 qed (simp_all add: R)
```
```   320
```
```   321 ML_setup {*
```
```   322   simpset_ref() := simpset() setsubgoaler asm_simp_tac;
```
```   323 *}
```
```   324
```
```   325 lemma (in UP_cring) UP_l_one [simp]:
```
```   326   assumes R: "p \<in> carrier P"
```
```   327   shows "\<one>\<^bsub>P\<^esub> \<otimes>\<^bsub>P\<^esub> p = p"
```
```   328 proof (rule up_eqI)
```
```   329   fix n
```
```   330   show "coeff P (\<one>\<^bsub>P\<^esub> \<otimes>\<^bsub>P\<^esub> p) n = coeff P p n"
```
```   331   proof (cases n)
```
```   332     case 0 with R show ?thesis by simp
```
```   333   next
```
```   334     case Suc with R show ?thesis
```
```   335       by (simp del: finsum_Suc add: finsum_Suc2 Pi_def)
```
```   336   qed
```
```   337 qed (simp_all add: R)
```
```   338
```
```   339 lemma (in UP_cring) UP_l_distr:
```
```   340   assumes R: "p \<in> carrier P" "q \<in> carrier P" "r \<in> carrier P"
```
```   341   shows "(p \<oplus>\<^bsub>P\<^esub> q) \<otimes>\<^bsub>P\<^esub> r = (p \<otimes>\<^bsub>P\<^esub> r) \<oplus>\<^bsub>P\<^esub> (q \<otimes>\<^bsub>P\<^esub> r)"
```
```   342   by (rule up_eqI) (simp add: l_distr R Pi_def, simp_all add: R)
```
```   343
```
```   344 lemma (in UP_cring) UP_m_comm:
```
```   345   assumes R: "p \<in> carrier P" "q \<in> carrier P"
```
```   346   shows "p \<otimes>\<^bsub>P\<^esub> q = q \<otimes>\<^bsub>P\<^esub> p"
```
```   347 proof (rule up_eqI)
```
```   348   fix n
```
```   349   {
```
```   350     fix k and a b :: "nat=>'a"
```
```   351     assume R: "a \<in> UNIV -> carrier R" "b \<in> UNIV -> carrier R"
```
```   352     then have "k <= n ==>
```
```   353       (\<Oplus>i \<in> {..k}. a i \<otimes> b (n-i)) =
```
```   354       (\<Oplus>i \<in> {..k}. a (k-i) \<otimes> b (i+n-k))"
```
```   355       (concl is "?eq k")
```
```   356     proof (induct k)
```
```   357       case 0 then show ?case by (simp add: Pi_def)
```
```   358     next
```
```   359       case (Suc k) then show ?case
```
```   360         by (subst finsum_Suc2) (simp add: Pi_def a_comm)+
```
```   361     qed
```
```   362   }
```
```   363   note l = this
```
```   364   from R show "coeff P (p \<otimes>\<^bsub>P\<^esub> q) n =  coeff P (q \<otimes>\<^bsub>P\<^esub> p) n"
```
```   365     apply (simp add: Pi_def)
```
```   366     apply (subst l)
```
```   367     apply (auto simp add: Pi_def)
```
```   368     apply (simp add: m_comm)
```
```   369     done
```
```   370 qed (simp_all add: R)
```
```   371
```
```   372 theorem (in UP_cring) UP_cring:
```
```   373   "cring P"
```
```   374   by (auto intro!: cringI abelian_groupI comm_monoidI UP_a_assoc UP_l_zero
```
```   375     UP_l_neg_ex UP_a_comm UP_m_assoc UP_l_one UP_m_comm UP_l_distr)
```
```   376
```
```   377 lemma (in UP_cring) UP_ring:  (* preliminary *)
```
```   378   "ring P"
```
```   379   by (auto intro: ring.intro cring.axioms UP_cring)
```
```   380
```
```   381 lemma (in UP_cring) UP_a_inv_closed [intro, simp]:
```
```   382   "p \<in> carrier P ==> \<ominus>\<^bsub>P\<^esub> p \<in> carrier P"
```
```   383   by (rule abelian_group.a_inv_closed
```
```   384     [OF ring.is_abelian_group [OF UP_ring]])
```
```   385
```
```   386 lemma (in UP_cring) coeff_a_inv [simp]:
```
```   387   assumes R: "p \<in> carrier P"
```
```   388   shows "coeff P (\<ominus>\<^bsub>P\<^esub> p) n = \<ominus> (coeff P p n)"
```
```   389 proof -
```
```   390   from R coeff_closed UP_a_inv_closed have
```
```   391     "coeff P (\<ominus>\<^bsub>P\<^esub> p) n = \<ominus> coeff P p n \<oplus> (coeff P p n \<oplus> coeff P (\<ominus>\<^bsub>P\<^esub> p) n)"
```
```   392     by algebra
```
```   393   also from R have "... =  \<ominus> (coeff P p n)"
```
```   394     by (simp del: coeff_add add: coeff_add [THEN sym]
```
```   395       abelian_group.r_neg [OF ring.is_abelian_group [OF UP_ring]])
```
```   396   finally show ?thesis .
```
```   397 qed
```
```   398
```
```   399 text {*
```
```   400   Instantiation of lemmas from @{term cring}.
```
```   401 *}
```
```   402
```
```   403 (* TODO: this should be automated with an instantiation command. *)
```
```   404
```
```   405 lemma (in UP_cring) UP_monoid:
```
```   406   "monoid P"
```
```   407   by (fast intro!: cring.is_comm_monoid comm_monoid.axioms monoid.intro
```
```   408     UP_cring)
```
```   409 (* TODO: provide cring.is_monoid *)
```
```   410
```
```   411 lemma (in UP_cring) UP_comm_monoid:
```
```   412   "comm_monoid P"
```
```   413   by (fast intro!: cring.is_comm_monoid UP_cring)
```
```   414
```
```   415 lemma (in UP_cring) UP_abelian_monoid:
```
```   416   "abelian_monoid P"
```
```   417   by (fast intro!: abelian_group.axioms ring.is_abelian_group UP_ring)
```
```   418
```
```   419 lemma (in UP_cring) UP_abelian_group:
```
```   420   "abelian_group P"
```
```   421   by (fast intro!: ring.is_abelian_group UP_ring)
```
```   422
```
```   423 lemmas (in UP_cring) UP_r_one [simp] =
```
```   424   monoid.r_one [OF UP_monoid]
```
```   425
```
```   426 lemmas (in UP_cring) UP_nat_pow_closed [intro, simp] =
```
```   427   monoid.nat_pow_closed [OF UP_monoid]
```
```   428
```
```   429 lemmas (in UP_cring) UP_nat_pow_0 [simp] =
```
```   430   monoid.nat_pow_0 [OF UP_monoid]
```
```   431
```
```   432 lemmas (in UP_cring) UP_nat_pow_Suc [simp] =
```
```   433   monoid.nat_pow_Suc [OF UP_monoid]
```
```   434
```
```   435 lemmas (in UP_cring) UP_nat_pow_one [simp] =
```
```   436   monoid.nat_pow_one [OF UP_monoid]
```
```   437
```
```   438 lemmas (in UP_cring) UP_nat_pow_mult =
```
```   439   monoid.nat_pow_mult [OF UP_monoid]
```
```   440
```
```   441 lemmas (in UP_cring) UP_nat_pow_pow =
```
```   442   monoid.nat_pow_pow [OF UP_monoid]
```
```   443
```
```   444 lemmas (in UP_cring) UP_m_lcomm =
```
```   445   comm_monoid.m_lcomm [OF UP_comm_monoid]
```
```   446
```
```   447 lemmas (in UP_cring) UP_m_ac = UP_m_assoc UP_m_comm UP_m_lcomm
```
```   448
```
```   449 lemmas (in UP_cring) UP_nat_pow_distr =
```
```   450   comm_monoid.nat_pow_distr [OF UP_comm_monoid]
```
```   451
```
```   452 lemmas (in UP_cring) UP_a_lcomm = abelian_monoid.a_lcomm [OF UP_abelian_monoid]
```
```   453
```
```   454 lemmas (in UP_cring) UP_r_zero [simp] =
```
```   455   abelian_monoid.r_zero [OF UP_abelian_monoid]
```
```   456
```
```   457 lemmas (in UP_cring) UP_a_ac = UP_a_assoc UP_a_comm UP_a_lcomm
```
```   458
```
```   459 lemmas (in UP_cring) UP_finsum_empty [simp] =
```
```   460   abelian_monoid.finsum_empty [OF UP_abelian_monoid]
```
```   461
```
```   462 lemmas (in UP_cring) UP_finsum_insert [simp] =
```
```   463   abelian_monoid.finsum_insert [OF UP_abelian_monoid]
```
```   464
```
```   465 lemmas (in UP_cring) UP_finsum_zero [simp] =
```
```   466   abelian_monoid.finsum_zero [OF UP_abelian_monoid]
```
```   467
```
```   468 lemmas (in UP_cring) UP_finsum_closed [simp] =
```
```   469   abelian_monoid.finsum_closed [OF UP_abelian_monoid]
```
```   470
```
```   471 lemmas (in UP_cring) UP_finsum_Un_Int =
```
```   472   abelian_monoid.finsum_Un_Int [OF UP_abelian_monoid]
```
```   473
```
```   474 lemmas (in UP_cring) UP_finsum_Un_disjoint =
```
```   475   abelian_monoid.finsum_Un_disjoint [OF UP_abelian_monoid]
```
```   476
```
```   477 lemmas (in UP_cring) UP_finsum_addf =
```
```   478   abelian_monoid.finsum_addf [OF UP_abelian_monoid]
```
```   479
```
```   480 lemmas (in UP_cring) UP_finsum_cong' =
```
```   481   abelian_monoid.finsum_cong' [OF UP_abelian_monoid]
```
```   482
```
```   483 lemmas (in UP_cring) UP_finsum_0 [simp] =
```
```   484   abelian_monoid.finsum_0 [OF UP_abelian_monoid]
```
```   485
```
```   486 lemmas (in UP_cring) UP_finsum_Suc [simp] =
```
```   487   abelian_monoid.finsum_Suc [OF UP_abelian_monoid]
```
```   488
```
```   489 lemmas (in UP_cring) UP_finsum_Suc2 =
```
```   490   abelian_monoid.finsum_Suc2 [OF UP_abelian_monoid]
```
```   491
```
```   492 lemmas (in UP_cring) UP_finsum_add [simp] =
```
```   493   abelian_monoid.finsum_add [OF UP_abelian_monoid]
```
```   494
```
```   495 lemmas (in UP_cring) UP_finsum_cong =
```
```   496   abelian_monoid.finsum_cong [OF UP_abelian_monoid]
```
```   497
```
```   498 lemmas (in UP_cring) UP_minus_closed [intro, simp] =
```
```   499   abelian_group.minus_closed [OF UP_abelian_group]
```
```   500
```
```   501 lemmas (in UP_cring) UP_a_l_cancel [simp] =
```
```   502   abelian_group.a_l_cancel [OF UP_abelian_group]
```
```   503
```
```   504 lemmas (in UP_cring) UP_a_r_cancel [simp] =
```
```   505   abelian_group.a_r_cancel [OF UP_abelian_group]
```
```   506
```
```   507 lemmas (in UP_cring) UP_l_neg =
```
```   508   abelian_group.l_neg [OF UP_abelian_group]
```
```   509
```
```   510 lemmas (in UP_cring) UP_r_neg =
```
```   511   abelian_group.r_neg [OF UP_abelian_group]
```
```   512
```
```   513 lemmas (in UP_cring) UP_minus_zero [simp] =
```
```   514   abelian_group.minus_zero [OF UP_abelian_group]
```
```   515
```
```   516 lemmas (in UP_cring) UP_minus_minus [simp] =
```
```   517   abelian_group.minus_minus [OF UP_abelian_group]
```
```   518
```
```   519 lemmas (in UP_cring) UP_minus_add =
```
```   520   abelian_group.minus_add [OF UP_abelian_group]
```
```   521
```
```   522 lemmas (in UP_cring) UP_r_neg2 =
```
```   523   abelian_group.r_neg2 [OF UP_abelian_group]
```
```   524
```
```   525 lemmas (in UP_cring) UP_r_neg1 =
```
```   526   abelian_group.r_neg1 [OF UP_abelian_group]
```
```   527
```
```   528 lemmas (in UP_cring) UP_r_distr =
```
```   529   ring.r_distr [OF UP_ring]
```
```   530
```
```   531 lemmas (in UP_cring) UP_l_null [simp] =
```
```   532   ring.l_null [OF UP_ring]
```
```   533
```
```   534 lemmas (in UP_cring) UP_r_null [simp] =
```
```   535   ring.r_null [OF UP_ring]
```
```   536
```
```   537 lemmas (in UP_cring) UP_l_minus =
```
```   538   ring.l_minus [OF UP_ring]
```
```   539
```
```   540 lemmas (in UP_cring) UP_r_minus =
```
```   541   ring.r_minus [OF UP_ring]
```
```   542
```
```   543 lemmas (in UP_cring) UP_finsum_ldistr =
```
```   544   cring.finsum_ldistr [OF UP_cring]
```
```   545
```
```   546 lemmas (in UP_cring) UP_finsum_rdistr =
```
```   547   cring.finsum_rdistr [OF UP_cring]
```
```   548
```
```   549
```
```   550 subsection {* Polynomials form an Algebra *}
```
```   551
```
```   552 lemma (in UP_cring) UP_smult_l_distr:
```
```   553   "[| a \<in> carrier R; b \<in> carrier R; p \<in> carrier P |] ==>
```
```   554   (a \<oplus> b) \<odot>\<^bsub>P\<^esub> p = a \<odot>\<^bsub>P\<^esub> p \<oplus>\<^bsub>P\<^esub> b \<odot>\<^bsub>P\<^esub> p"
```
```   555   by (rule up_eqI) (simp_all add: R.l_distr)
```
```   556
```
```   557 lemma (in UP_cring) UP_smult_r_distr:
```
```   558   "[| a \<in> carrier R; p \<in> carrier P; q \<in> carrier P |] ==>
```
```   559   a \<odot>\<^bsub>P\<^esub> (p \<oplus>\<^bsub>P\<^esub> q) = a \<odot>\<^bsub>P\<^esub> p \<oplus>\<^bsub>P\<^esub> a \<odot>\<^bsub>P\<^esub> q"
```
```   560   by (rule up_eqI) (simp_all add: R.r_distr)
```
```   561
```
```   562 lemma (in UP_cring) UP_smult_assoc1:
```
```   563       "[| a \<in> carrier R; b \<in> carrier R; p \<in> carrier P |] ==>
```
```   564       (a \<otimes> b) \<odot>\<^bsub>P\<^esub> p = a \<odot>\<^bsub>P\<^esub> (b \<odot>\<^bsub>P\<^esub> p)"
```
```   565   by (rule up_eqI) (simp_all add: R.m_assoc)
```
```   566
```
```   567 lemma (in UP_cring) UP_smult_one [simp]:
```
```   568       "p \<in> carrier P ==> \<one> \<odot>\<^bsub>P\<^esub> p = p"
```
```   569   by (rule up_eqI) simp_all
```
```   570
```
```   571 lemma (in UP_cring) UP_smult_assoc2:
```
```   572   "[| a \<in> carrier R; p \<in> carrier P; q \<in> carrier P |] ==>
```
```   573   (a \<odot>\<^bsub>P\<^esub> p) \<otimes>\<^bsub>P\<^esub> q = a \<odot>\<^bsub>P\<^esub> (p \<otimes>\<^bsub>P\<^esub> q)"
```
```   574   by (rule up_eqI) (simp_all add: R.finsum_rdistr R.m_assoc Pi_def)
```
```   575
```
```   576 text {*
```
```   577   Instantiation of lemmas from @{term algebra}.
```
```   578 *}
```
```   579
```
```   580 (* TODO: this should be automated with an instantiation command. *)
```
```   581
```
```   582 (* TODO: move to CRing.thy, really a fact missing from the locales package *)
```
```   583 lemma (in cring) cring:
```
```   584   "cring R"
```
```   585   by (fast intro: cring.intro prems)
```
```   586
```
```   587 lemma (in UP_cring) UP_algebra:
```
```   588   "algebra R P"
```
```   589   by (auto intro: algebraI cring UP_cring UP_smult_l_distr UP_smult_r_distr
```
```   590     UP_smult_assoc1 UP_smult_assoc2)
```
```   591
```
```   592 lemmas (in UP_cring) UP_smult_l_null [simp] =
```
```   593   algebra.smult_l_null [OF UP_algebra]
```
```   594
```
```   595 lemmas (in UP_cring) UP_smult_r_null [simp] =
```
```   596   algebra.smult_r_null [OF UP_algebra]
```
```   597
```
```   598 lemmas (in UP_cring) UP_smult_l_minus =
```
```   599   algebra.smult_l_minus [OF UP_algebra]
```
```   600
```
```   601 lemmas (in UP_cring) UP_smult_r_minus =
```
```   602   algebra.smult_r_minus [OF UP_algebra]
```
```   603
```
```   604 subsection {* Further lemmas involving monomials *}
```
```   605
```
```   606 lemma (in UP_cring) monom_zero [simp]:
```
```   607   "monom P \<zero> n = \<zero>\<^bsub>P\<^esub>"
```
```   608   by (simp add: UP_def P_def)
```
```   609
```
```   610 ML_setup {*
```
```   611   simpset_ref() := simpset() setsubgoaler asm_full_simp_tac;
```
```   612 *}
```
```   613
```
```   614 lemma (in UP_cring) monom_mult_is_smult:
```
```   615   assumes R: "a \<in> carrier R" "p \<in> carrier P"
```
```   616   shows "monom P a 0 \<otimes>\<^bsub>P\<^esub> p = a \<odot>\<^bsub>P\<^esub> p"
```
```   617 proof (rule up_eqI)
```
```   618   fix n
```
```   619   have "coeff P (p \<otimes>\<^bsub>P\<^esub> monom P a 0) n = coeff P (a \<odot>\<^bsub>P\<^esub> p) n"
```
```   620   proof (cases n)
```
```   621     case 0 with R show ?thesis by (simp add: R.m_comm)
```
```   622   next
```
```   623     case Suc with R show ?thesis
```
```   624       by (simp cong: finsum_cong add: R.r_null Pi_def)
```
```   625         (simp add: m_comm)
```
```   626   qed
```
```   627   with R show "coeff P (monom P a 0 \<otimes>\<^bsub>P\<^esub> p) n = coeff P (a \<odot>\<^bsub>P\<^esub> p) n"
```
```   628     by (simp add: UP_m_comm)
```
```   629 qed (simp_all add: R)
```
```   630
```
```   631 ML_setup {*
```
```   632   simpset_ref() := simpset() setsubgoaler asm_simp_tac;
```
```   633 *}
```
```   634
```
```   635 lemma (in UP_cring) monom_add [simp]:
```
```   636   "[| a \<in> carrier R; b \<in> carrier R |] ==>
```
```   637   monom P (a \<oplus> b) n = monom P a n \<oplus>\<^bsub>P\<^esub> monom P b n"
```
```   638   by (rule up_eqI) simp_all
```
```   639
```
```   640 ML_setup {*
```
```   641   simpset_ref() := simpset() setsubgoaler asm_full_simp_tac;
```
```   642 *}
```
```   643
```
```   644 lemma (in UP_cring) monom_one_Suc:
```
```   645   "monom P \<one> (Suc n) = monom P \<one> n \<otimes>\<^bsub>P\<^esub> monom P \<one> 1"
```
```   646 proof (rule up_eqI)
```
```   647   fix k
```
```   648   show "coeff P (monom P \<one> (Suc n)) k = coeff P (monom P \<one> n \<otimes>\<^bsub>P\<^esub> monom P \<one> 1) k"
```
```   649   proof (cases "k = Suc n")
```
```   650     case True show ?thesis
```
```   651     proof -
```
```   652       from True have less_add_diff:
```
```   653         "!!i. [| n < i; i <= n + m |] ==> n + m - i < m" by arith
```
```   654       from True have "coeff P (monom P \<one> (Suc n)) k = \<one>" by simp
```
```   655       also from True
```
```   656       have "... = (\<Oplus>i \<in> {..<n} \<union> {n}. coeff P (monom P \<one> n) i \<otimes>
```
```   657         coeff P (monom P \<one> 1) (k - i))"
```
```   658         by (simp cong: finsum_cong add: finsum_Un_disjoint Pi_def)
```
```   659       also have "... = (\<Oplus>i \<in>  {..n}. coeff P (monom P \<one> n) i \<otimes>
```
```   660         coeff P (monom P \<one> 1) (k - i))"
```
```   661         by (simp only: ivl_disj_un_singleton)
```
```   662       also from True
```
```   663       have "... = (\<Oplus>i \<in> {..n} \<union> {n<..k}. coeff P (monom P \<one> n) i \<otimes>
```
```   664         coeff P (monom P \<one> 1) (k - i))"
```
```   665         by (simp cong: finsum_cong add: finsum_Un_disjoint ivl_disj_int_one
```
```   666           order_less_imp_not_eq Pi_def)
```
```   667       also from True have "... = coeff P (monom P \<one> n \<otimes>\<^bsub>P\<^esub> monom P \<one> 1) k"
```
```   668         by (simp add: ivl_disj_un_one)
```
```   669       finally show ?thesis .
```
```   670     qed
```
```   671   next
```
```   672     case False
```
```   673     note neq = False
```
```   674     let ?s =
```
```   675       "\<lambda>i. (if n = i then \<one> else \<zero>) \<otimes> (if Suc 0 = k - i then \<one> else \<zero>)"
```
```   676     from neq have "coeff P (monom P \<one> (Suc n)) k = \<zero>" by simp
```
```   677     also have "... = (\<Oplus>i \<in> {..k}. ?s i)"
```
```   678     proof -
```
```   679       have f1: "(\<Oplus>i \<in> {..<n}. ?s i) = \<zero>"
```
```   680         by (simp cong: finsum_cong add: Pi_def)
```
```   681       from neq have f2: "(\<Oplus>i \<in> {n}. ?s i) = \<zero>"
```
```   682         by (simp cong: finsum_cong add: Pi_def) arith
```
```   683       have f3: "n < k ==> (\<Oplus>i \<in> {n<..k}. ?s i) = \<zero>"
```
```   684         by (simp cong: finsum_cong add: order_less_imp_not_eq Pi_def)
```
```   685       show ?thesis
```
```   686       proof (cases "k < n")
```
```   687         case True then show ?thesis by (simp cong: finsum_cong add: Pi_def)
```
```   688       next
```
```   689         case False then have n_le_k: "n <= k" by arith
```
```   690         show ?thesis
```
```   691         proof (cases "n = k")
```
```   692           case True
```
```   693           then have "\<zero> = (\<Oplus>i \<in> {..<n} \<union> {n}. ?s i)"
```
```   694             by (simp cong: finsum_cong add: finsum_Un_disjoint
```
```   695               ivl_disj_int_singleton Pi_def)
```
```   696           also from True have "... = (\<Oplus>i \<in> {..k}. ?s i)"
```
```   697             by (simp only: ivl_disj_un_singleton)
```
```   698           finally show ?thesis .
```
```   699         next
```
```   700           case False with n_le_k have n_less_k: "n < k" by arith
```
```   701           with neq have "\<zero> = (\<Oplus>i \<in> {..<n} \<union> {n}. ?s i)"
```
```   702             by (simp add: finsum_Un_disjoint f1 f2
```
```   703               ivl_disj_int_singleton Pi_def del: Un_insert_right)
```
```   704           also have "... = (\<Oplus>i \<in> {..n}. ?s i)"
```
```   705             by (simp only: ivl_disj_un_singleton)
```
```   706           also from n_less_k neq have "... = (\<Oplus>i \<in> {..n} \<union> {n<..k}. ?s i)"
```
```   707             by (simp add: finsum_Un_disjoint f3 ivl_disj_int_one Pi_def)
```
```   708           also from n_less_k have "... = (\<Oplus>i \<in> {..k}. ?s i)"
```
```   709             by (simp only: ivl_disj_un_one)
```
```   710           finally show ?thesis .
```
```   711         qed
```
```   712       qed
```
```   713     qed
```
```   714     also have "... = coeff P (monom P \<one> n \<otimes>\<^bsub>P\<^esub> monom P \<one> 1) k" by simp
```
```   715     finally show ?thesis .
```
```   716   qed
```
```   717 qed (simp_all)
```
```   718
```
```   719 ML_setup {*
```
```   720   simpset_ref() := simpset() setsubgoaler asm_simp_tac;
```
```   721 *}
```
```   722
```
```   723 lemma (in UP_cring) monom_mult_smult:
```
```   724   "[| a \<in> carrier R; b \<in> carrier R |] ==> monom P (a \<otimes> b) n = a \<odot>\<^bsub>P\<^esub> monom P b n"
```
```   725   by (rule up_eqI) simp_all
```
```   726
```
```   727 lemma (in UP_cring) monom_one [simp]:
```
```   728   "monom P \<one> 0 = \<one>\<^bsub>P\<^esub>"
```
```   729   by (rule up_eqI) simp_all
```
```   730
```
```   731 lemma (in UP_cring) monom_one_mult:
```
```   732   "monom P \<one> (n + m) = monom P \<one> n \<otimes>\<^bsub>P\<^esub> monom P \<one> m"
```
```   733 proof (induct n)
```
```   734   case 0 show ?case by simp
```
```   735 next
```
```   736   case Suc then show ?case
```
```   737     by (simp only: add_Suc monom_one_Suc) (simp add: UP_m_ac)
```
```   738 qed
```
```   739
```
```   740 lemma (in UP_cring) monom_mult [simp]:
```
```   741   assumes R: "a \<in> carrier R" "b \<in> carrier R"
```
```   742   shows "monom P (a \<otimes> b) (n + m) = monom P a n \<otimes>\<^bsub>P\<^esub> monom P b m"
```
```   743 proof -
```
```   744   from R have "monom P (a \<otimes> b) (n + m) = monom P (a \<otimes> b \<otimes> \<one>) (n + m)" by simp
```
```   745   also from R have "... = a \<otimes> b \<odot>\<^bsub>P\<^esub> monom P \<one> (n + m)"
```
```   746     by (simp add: monom_mult_smult del: r_one)
```
```   747   also have "... = a \<otimes> b \<odot>\<^bsub>P\<^esub> (monom P \<one> n \<otimes>\<^bsub>P\<^esub> monom P \<one> m)"
```
```   748     by (simp only: monom_one_mult)
```
```   749   also from R have "... = a \<odot>\<^bsub>P\<^esub> (b \<odot>\<^bsub>P\<^esub> (monom P \<one> n \<otimes>\<^bsub>P\<^esub> monom P \<one> m))"
```
```   750     by (simp add: UP_smult_assoc1)
```
```   751   also from R have "... = a \<odot>\<^bsub>P\<^esub> (b \<odot>\<^bsub>P\<^esub> (monom P \<one> m \<otimes>\<^bsub>P\<^esub> monom P \<one> n))"
```
```   752     by (simp add: UP_m_comm)
```
```   753   also from R have "... = a \<odot>\<^bsub>P\<^esub> ((b \<odot>\<^bsub>P\<^esub> monom P \<one> m) \<otimes>\<^bsub>P\<^esub> monom P \<one> n)"
```
```   754     by (simp add: UP_smult_assoc2)
```
```   755   also from R have "... = a \<odot>\<^bsub>P\<^esub> (monom P \<one> n \<otimes>\<^bsub>P\<^esub> (b \<odot>\<^bsub>P\<^esub> monom P \<one> m))"
```
```   756     by (simp add: UP_m_comm)
```
```   757   also from R have "... = (a \<odot>\<^bsub>P\<^esub> monom P \<one> n) \<otimes>\<^bsub>P\<^esub> (b \<odot>\<^bsub>P\<^esub> monom P \<one> m)"
```
```   758     by (simp add: UP_smult_assoc2)
```
```   759   also from R have "... = monom P (a \<otimes> \<one>) n \<otimes>\<^bsub>P\<^esub> monom P (b \<otimes> \<one>) m"
```
```   760     by (simp add: monom_mult_smult del: r_one)
```
```   761   also from R have "... = monom P a n \<otimes>\<^bsub>P\<^esub> monom P b m" by simp
```
```   762   finally show ?thesis .
```
```   763 qed
```
```   764
```
```   765 lemma (in UP_cring) monom_a_inv [simp]:
```
```   766   "a \<in> carrier R ==> monom P (\<ominus> a) n = \<ominus>\<^bsub>P\<^esub> monom P a n"
```
```   767   by (rule up_eqI) simp_all
```
```   768
```
```   769 lemma (in UP_cring) monom_inj:
```
```   770   "inj_on (%a. monom P a n) (carrier R)"
```
```   771 proof (rule inj_onI)
```
```   772   fix x y
```
```   773   assume R: "x \<in> carrier R" "y \<in> carrier R" and eq: "monom P x n = monom P y n"
```
```   774   then have "coeff P (monom P x n) n = coeff P (monom P y n) n" by simp
```
```   775   with R show "x = y" by simp
```
```   776 qed
```
```   777
```
```   778 subsection {* The degree function *}
```
```   779
```
```   780 constdefs (structure R)
```
```   781   deg :: "[('a, 'm) ring_scheme, nat => 'a] => nat"
```
```   782   "deg R p == LEAST n. bound \<zero> n (coeff (UP R) p)"
```
```   783
```
```   784 lemma (in UP_cring) deg_aboveI:
```
```   785   "[| (!!m. n < m ==> coeff P p m = \<zero>); p \<in> carrier P |] ==> deg R p <= n"
```
```   786   by (unfold deg_def P_def) (fast intro: Least_le)
```
```   787
```
```   788 (*
```
```   789 lemma coeff_bound_ex: "EX n. bound n (coeff p)"
```
```   790 proof -
```
```   791   have "(%n. coeff p n) : UP" by (simp add: coeff_def Rep_UP)
```
```   792   then obtain n where "bound n (coeff p)" by (unfold UP_def) fast
```
```   793   then show ?thesis ..
```
```   794 qed
```
```   795
```
```   796 lemma bound_coeff_obtain:
```
```   797   assumes prem: "(!!n. bound n (coeff p) ==> P)" shows "P"
```
```   798 proof -
```
```   799   have "(%n. coeff p n) : UP" by (simp add: coeff_def Rep_UP)
```
```   800   then obtain n where "bound n (coeff p)" by (unfold UP_def) fast
```
```   801   with prem show P .
```
```   802 qed
```
```   803 *)
```
```   804
```
```   805 lemma (in UP_cring) deg_aboveD:
```
```   806   "[| deg R p < m; p \<in> carrier P |] ==> coeff P p m = \<zero>"
```
```   807 proof -
```
```   808   assume R: "p \<in> carrier P" and "deg R p < m"
```
```   809   from R obtain n where "bound \<zero> n (coeff P p)"
```
```   810     by (auto simp add: UP_def P_def)
```
```   811   then have "bound \<zero> (deg R p) (coeff P p)"
```
```   812     by (auto simp: deg_def P_def dest: LeastI)
```
```   813   then show ?thesis ..
```
```   814 qed
```
```   815
```
```   816 lemma (in UP_cring) deg_belowI:
```
```   817   assumes non_zero: "n ~= 0 ==> coeff P p n ~= \<zero>"
```
```   818     and R: "p \<in> carrier P"
```
```   819   shows "n <= deg R p"
```
```   820 -- {* Logically, this is a slightly stronger version of
```
```   821    @{thm [source] deg_aboveD} *}
```
```   822 proof (cases "n=0")
```
```   823   case True then show ?thesis by simp
```
```   824 next
```
```   825   case False then have "coeff P p n ~= \<zero>" by (rule non_zero)
```
```   826   then have "~ deg R p < n" by (fast dest: deg_aboveD intro: R)
```
```   827   then show ?thesis by arith
```
```   828 qed
```
```   829
```
```   830 lemma (in UP_cring) lcoeff_nonzero_deg:
```
```   831   assumes deg: "deg R p ~= 0" and R: "p \<in> carrier P"
```
```   832   shows "coeff P p (deg R p) ~= \<zero>"
```
```   833 proof -
```
```   834   from R obtain m where "deg R p <= m" and m_coeff: "coeff P p m ~= \<zero>"
```
```   835   proof -
```
```   836     have minus: "!!(n::nat) m. n ~= 0 ==> (n - Suc 0 < m) = (n <= m)"
```
```   837       by arith
```
```   838 (* TODO: why does simplification below not work with "1" *)
```
```   839     from deg have "deg R p - 1 < (LEAST n. bound \<zero> n (coeff P p))"
```
```   840       by (unfold deg_def P_def) arith
```
```   841     then have "~ bound \<zero> (deg R p - 1) (coeff P p)" by (rule not_less_Least)
```
```   842     then have "EX m. deg R p - 1 < m & coeff P p m ~= \<zero>"
```
```   843       by (unfold bound_def) fast
```
```   844     then have "EX m. deg R p <= m & coeff P p m ~= \<zero>" by (simp add: deg minus)
```
```   845     then show ?thesis by auto
```
```   846   qed
```
```   847   with deg_belowI R have "deg R p = m" by fastsimp
```
```   848   with m_coeff show ?thesis by simp
```
```   849 qed
```
```   850
```
```   851 lemma (in UP_cring) lcoeff_nonzero_nonzero:
```
```   852   assumes deg: "deg R p = 0" and nonzero: "p ~= \<zero>\<^bsub>P\<^esub>" and R: "p \<in> carrier P"
```
```   853   shows "coeff P p 0 ~= \<zero>"
```
```   854 proof -
```
```   855   have "EX m. coeff P p m ~= \<zero>"
```
```   856   proof (rule classical)
```
```   857     assume "~ ?thesis"
```
```   858     with R have "p = \<zero>\<^bsub>P\<^esub>" by (auto intro: up_eqI)
```
```   859     with nonzero show ?thesis by contradiction
```
```   860   qed
```
```   861   then obtain m where coeff: "coeff P p m ~= \<zero>" ..
```
```   862   then have "m <= deg R p" by (rule deg_belowI)
```
```   863   then have "m = 0" by (simp add: deg)
```
```   864   with coeff show ?thesis by simp
```
```   865 qed
```
```   866
```
```   867 lemma (in UP_cring) lcoeff_nonzero:
```
```   868   assumes neq: "p ~= \<zero>\<^bsub>P\<^esub>" and R: "p \<in> carrier P"
```
```   869   shows "coeff P p (deg R p) ~= \<zero>"
```
```   870 proof (cases "deg R p = 0")
```
```   871   case True with neq R show ?thesis by (simp add: lcoeff_nonzero_nonzero)
```
```   872 next
```
```   873   case False with neq R show ?thesis by (simp add: lcoeff_nonzero_deg)
```
```   874 qed
```
```   875
```
```   876 lemma (in UP_cring) deg_eqI:
```
```   877   "[| !!m. n < m ==> coeff P p m = \<zero>;
```
```   878       !!n. n ~= 0 ==> coeff P p n ~= \<zero>; p \<in> carrier P |] ==> deg R p = n"
```
```   879 by (fast intro: le_anti_sym deg_aboveI deg_belowI)
```
```   880
```
```   881 (* Degree and polynomial operations *)
```
```   882
```
```   883 lemma (in UP_cring) deg_add [simp]:
```
```   884   assumes R: "p \<in> carrier P" "q \<in> carrier P"
```
```   885   shows "deg R (p \<oplus>\<^bsub>P\<^esub> q) <= max (deg R p) (deg R q)"
```
```   886 proof (cases "deg R p <= deg R q")
```
```   887   case True show ?thesis
```
```   888     by (rule deg_aboveI) (simp_all add: True R deg_aboveD)
```
```   889 next
```
```   890   case False show ?thesis
```
```   891     by (rule deg_aboveI) (simp_all add: False R deg_aboveD)
```
```   892 qed
```
```   893
```
```   894 lemma (in UP_cring) deg_monom_le:
```
```   895   "a \<in> carrier R ==> deg R (monom P a n) <= n"
```
```   896   by (intro deg_aboveI) simp_all
```
```   897
```
```   898 lemma (in UP_cring) deg_monom [simp]:
```
```   899   "[| a ~= \<zero>; a \<in> carrier R |] ==> deg R (monom P a n) = n"
```
```   900   by (fastsimp intro: le_anti_sym deg_aboveI deg_belowI)
```
```   901
```
```   902 lemma (in UP_cring) deg_const [simp]:
```
```   903   assumes R: "a \<in> carrier R" shows "deg R (monom P a 0) = 0"
```
```   904 proof (rule le_anti_sym)
```
```   905   show "deg R (monom P a 0) <= 0" by (rule deg_aboveI) (simp_all add: R)
```
```   906 next
```
```   907   show "0 <= deg R (monom P a 0)" by (rule deg_belowI) (simp_all add: R)
```
```   908 qed
```
```   909
```
```   910 lemma (in UP_cring) deg_zero [simp]:
```
```   911   "deg R \<zero>\<^bsub>P\<^esub> = 0"
```
```   912 proof (rule le_anti_sym)
```
```   913   show "deg R \<zero>\<^bsub>P\<^esub> <= 0" by (rule deg_aboveI) simp_all
```
```   914 next
```
```   915   show "0 <= deg R \<zero>\<^bsub>P\<^esub>" by (rule deg_belowI) simp_all
```
```   916 qed
```
```   917
```
```   918 lemma (in UP_cring) deg_one [simp]:
```
```   919   "deg R \<one>\<^bsub>P\<^esub> = 0"
```
```   920 proof (rule le_anti_sym)
```
```   921   show "deg R \<one>\<^bsub>P\<^esub> <= 0" by (rule deg_aboveI) simp_all
```
```   922 next
```
```   923   show "0 <= deg R \<one>\<^bsub>P\<^esub>" by (rule deg_belowI) simp_all
```
```   924 qed
```
```   925
```
```   926 lemma (in UP_cring) deg_uminus [simp]:
```
```   927   assumes R: "p \<in> carrier P" shows "deg R (\<ominus>\<^bsub>P\<^esub> p) = deg R p"
```
```   928 proof (rule le_anti_sym)
```
```   929   show "deg R (\<ominus>\<^bsub>P\<^esub> p) <= deg R p" by (simp add: deg_aboveI deg_aboveD R)
```
```   930 next
```
```   931   show "deg R p <= deg R (\<ominus>\<^bsub>P\<^esub> p)"
```
```   932     by (simp add: deg_belowI lcoeff_nonzero_deg
```
```   933       inj_on_iff [OF a_inv_inj, of _ "\<zero>", simplified] R)
```
```   934 qed
```
```   935
```
```   936 lemma (in UP_domain) deg_smult_ring:
```
```   937   "[| a \<in> carrier R; p \<in> carrier P |] ==>
```
```   938   deg R (a \<odot>\<^bsub>P\<^esub> p) <= (if a = \<zero> then 0 else deg R p)"
```
```   939   by (cases "a = \<zero>") (simp add: deg_aboveI deg_aboveD)+
```
```   940
```
```   941 lemma (in UP_domain) deg_smult [simp]:
```
```   942   assumes R: "a \<in> carrier R" "p \<in> carrier P"
```
```   943   shows "deg R (a \<odot>\<^bsub>P\<^esub> p) = (if a = \<zero> then 0 else deg R p)"
```
```   944 proof (rule le_anti_sym)
```
```   945   show "deg R (a \<odot>\<^bsub>P\<^esub> p) <= (if a = \<zero> then 0 else deg R p)"
```
```   946     by (rule deg_smult_ring)
```
```   947 next
```
```   948   show "(if a = \<zero> then 0 else deg R p) <= deg R (a \<odot>\<^bsub>P\<^esub> p)"
```
```   949   proof (cases "a = \<zero>")
```
```   950   qed (simp, simp add: deg_belowI lcoeff_nonzero_deg integral_iff R)
```
```   951 qed
```
```   952
```
```   953 lemma (in UP_cring) deg_mult_cring:
```
```   954   assumes R: "p \<in> carrier P" "q \<in> carrier P"
```
```   955   shows "deg R (p \<otimes>\<^bsub>P\<^esub> q) <= deg R p + deg R q"
```
```   956 proof (rule deg_aboveI)
```
```   957   fix m
```
```   958   assume boundm: "deg R p + deg R q < m"
```
```   959   {
```
```   960     fix k i
```
```   961     assume boundk: "deg R p + deg R q < k"
```
```   962     then have "coeff P p i \<otimes> coeff P q (k - i) = \<zero>"
```
```   963     proof (cases "deg R p < i")
```
```   964       case True then show ?thesis by (simp add: deg_aboveD R)
```
```   965     next
```
```   966       case False with boundk have "deg R q < k - i" by arith
```
```   967       then show ?thesis by (simp add: deg_aboveD R)
```
```   968     qed
```
```   969   }
```
```   970   with boundm R show "coeff P (p \<otimes>\<^bsub>P\<^esub> q) m = \<zero>" by simp
```
```   971 qed (simp add: R)
```
```   972
```
```   973 ML_setup {*
```
```   974   simpset_ref() := simpset() setsubgoaler asm_full_simp_tac;
```
```   975 *}
```
```   976
```
```   977 lemma (in UP_domain) deg_mult [simp]:
```
```   978   "[| p ~= \<zero>\<^bsub>P\<^esub>; q ~= \<zero>\<^bsub>P\<^esub>; p \<in> carrier P; q \<in> carrier P |] ==>
```
```   979   deg R (p \<otimes>\<^bsub>P\<^esub> q) = deg R p + deg R q"
```
```   980 proof (rule le_anti_sym)
```
```   981   assume "p \<in> carrier P" " q \<in> carrier P"
```
```   982   show "deg R (p \<otimes>\<^bsub>P\<^esub> q) <= deg R p + deg R q" by (rule deg_mult_cring)
```
```   983 next
```
```   984   let ?s = "(%i. coeff P p i \<otimes> coeff P q (deg R p + deg R q - i))"
```
```   985   assume R: "p \<in> carrier P" "q \<in> carrier P" and nz: "p ~= \<zero>\<^bsub>P\<^esub>" "q ~= \<zero>\<^bsub>P\<^esub>"
```
```   986   have less_add_diff: "!!(k::nat) n m. k < n ==> m < n + m - k" by arith
```
```   987   show "deg R p + deg R q <= deg R (p \<otimes>\<^bsub>P\<^esub> q)"
```
```   988   proof (rule deg_belowI, simp add: R)
```
```   989     have "(\<Oplus>i \<in> {.. deg R p + deg R q}. ?s i)
```
```   990       = (\<Oplus>i \<in> {..< deg R p} \<union> {deg R p .. deg R p + deg R q}. ?s i)"
```
```   991       by (simp only: ivl_disj_un_one)
```
```   992     also have "... = (\<Oplus>i \<in> {deg R p .. deg R p + deg R q}. ?s i)"
```
```   993       by (simp cong: finsum_cong add: finsum_Un_disjoint ivl_disj_int_one
```
```   994         deg_aboveD less_add_diff R Pi_def)
```
```   995     also have "...= (\<Oplus>i \<in> {deg R p} \<union> {deg R p <.. deg R p + deg R q}. ?s i)"
```
```   996       by (simp only: ivl_disj_un_singleton)
```
```   997     also have "... = coeff P p (deg R p) \<otimes> coeff P q (deg R q)"
```
```   998       by (simp cong: finsum_cong add: finsum_Un_disjoint
```
```   999         ivl_disj_int_singleton deg_aboveD R Pi_def)
```
```  1000     finally have "(\<Oplus>i \<in> {.. deg R p + deg R q}. ?s i)
```
```  1001       = coeff P p (deg R p) \<otimes> coeff P q (deg R q)" .
```
```  1002     with nz show "(\<Oplus>i \<in> {.. deg R p + deg R q}. ?s i) ~= \<zero>"
```
```  1003       by (simp add: integral_iff lcoeff_nonzero R)
```
```  1004     qed (simp add: R)
```
```  1005   qed
```
```  1006
```
```  1007 lemma (in UP_cring) coeff_finsum:
```
```  1008   assumes fin: "finite A"
```
```  1009   shows "p \<in> A -> carrier P ==>
```
```  1010     coeff P (finsum P p A) k = (\<Oplus>i \<in> A. coeff P (p i) k)"
```
```  1011   using fin by induct (auto simp: Pi_def)
```
```  1012
```
```  1013 ML_setup {*
```
```  1014   simpset_ref() := simpset() setsubgoaler asm_full_simp_tac;
```
```  1015 *}
```
```  1016
```
```  1017 lemma (in UP_cring) up_repr:
```
```  1018   assumes R: "p \<in> carrier P"
```
```  1019   shows "(\<Oplus>\<^bsub>P\<^esub> i \<in> {..deg R p}. monom P (coeff P p i) i) = p"
```
```  1020 proof (rule up_eqI)
```
```  1021   let ?s = "(%i. monom P (coeff P p i) i)"
```
```  1022   fix k
```
```  1023   from R have RR: "!!i. (if i = k then coeff P p i else \<zero>) \<in> carrier R"
```
```  1024     by simp
```
```  1025   show "coeff P (\<Oplus>\<^bsub>P\<^esub> i \<in> {..deg R p}. ?s i) k = coeff P p k"
```
```  1026   proof (cases "k <= deg R p")
```
```  1027     case True
```
```  1028     hence "coeff P (\<Oplus>\<^bsub>P\<^esub> i \<in> {..deg R p}. ?s i) k =
```
```  1029           coeff P (\<Oplus>\<^bsub>P\<^esub> i \<in> {..k} \<union> {k<..deg R p}. ?s i) k"
```
```  1030       by (simp only: ivl_disj_un_one)
```
```  1031     also from True
```
```  1032     have "... = coeff P (\<Oplus>\<^bsub>P\<^esub> i \<in> {..k}. ?s i) k"
```
```  1033       by (simp cong: finsum_cong add: finsum_Un_disjoint
```
```  1034         ivl_disj_int_one order_less_imp_not_eq2 coeff_finsum R RR Pi_def)
```
```  1035     also
```
```  1036     have "... = coeff P (\<Oplus>\<^bsub>P\<^esub> i \<in> {..<k} \<union> {k}. ?s i) k"
```
```  1037       by (simp only: ivl_disj_un_singleton)
```
```  1038     also have "... = coeff P p k"
```
```  1039       by (simp cong: finsum_cong add: setsum_Un_disjoint
```
```  1040         ivl_disj_int_singleton coeff_finsum deg_aboveD R RR Pi_def)
```
```  1041     finally show ?thesis .
```
```  1042   next
```
```  1043     case False
```
```  1044     hence "coeff P (\<Oplus>\<^bsub>P\<^esub> i \<in> {..deg R p}. ?s i) k =
```
```  1045           coeff P (\<Oplus>\<^bsub>P\<^esub> i \<in> {..<deg R p} \<union> {deg R p}. ?s i) k"
```
```  1046       by (simp only: ivl_disj_un_singleton)
```
```  1047     also from False have "... = coeff P p k"
```
```  1048       by (simp cong: finsum_cong add: setsum_Un_disjoint ivl_disj_int_singleton
```
```  1049         coeff_finsum deg_aboveD R Pi_def)
```
```  1050     finally show ?thesis .
```
```  1051   qed
```
```  1052 qed (simp_all add: R Pi_def)
```
```  1053
```
```  1054 lemma (in UP_cring) up_repr_le:
```
```  1055   "[| deg R p <= n; p \<in> carrier P |] ==>
```
```  1056   (\<Oplus>\<^bsub>P\<^esub> i \<in> {..n}. monom P (coeff P p i) i) = p"
```
```  1057 proof -
```
```  1058   let ?s = "(%i. monom P (coeff P p i) i)"
```
```  1059   assume R: "p \<in> carrier P" and "deg R p <= n"
```
```  1060   then have "finsum P ?s {..n} = finsum P ?s ({..deg R p} \<union> {deg R p<..n})"
```
```  1061     by (simp only: ivl_disj_un_one)
```
```  1062   also have "... = finsum P ?s {..deg R p}"
```
```  1063     by (simp cong: UP_finsum_cong add: UP_finsum_Un_disjoint ivl_disj_int_one
```
```  1064       deg_aboveD R Pi_def)
```
```  1065   also have "... = p" by (rule up_repr)
```
```  1066   finally show ?thesis .
```
```  1067 qed
```
```  1068
```
```  1069 ML_setup {*
```
```  1070   simpset_ref() := simpset() setsubgoaler asm_simp_tac;
```
```  1071 *}
```
```  1072
```
```  1073 subsection {* Polynomials over an integral domain form an integral domain *}
```
```  1074
```
```  1075 lemma domainI:
```
```  1076   assumes cring: "cring R"
```
```  1077     and one_not_zero: "one R ~= zero R"
```
```  1078     and integral: "!!a b. [| mult R a b = zero R; a \<in> carrier R;
```
```  1079       b \<in> carrier R |] ==> a = zero R | b = zero R"
```
```  1080   shows "domain R"
```
```  1081   by (auto intro!: domain.intro domain_axioms.intro cring.axioms prems
```
```  1082     del: disjCI)
```
```  1083
```
```  1084 lemma (in UP_domain) UP_one_not_zero:
```
```  1085   "\<one>\<^bsub>P\<^esub> ~= \<zero>\<^bsub>P\<^esub>"
```
```  1086 proof
```
```  1087   assume "\<one>\<^bsub>P\<^esub> = \<zero>\<^bsub>P\<^esub>"
```
```  1088   hence "coeff P \<one>\<^bsub>P\<^esub> 0 = (coeff P \<zero>\<^bsub>P\<^esub> 0)" by simp
```
```  1089   hence "\<one> = \<zero>" by simp
```
```  1090   with one_not_zero show "False" by contradiction
```
```  1091 qed
```
```  1092
```
```  1093 lemma (in UP_domain) UP_integral:
```
```  1094   "[| p \<otimes>\<^bsub>P\<^esub> q = \<zero>\<^bsub>P\<^esub>; p \<in> carrier P; q \<in> carrier P |] ==> p = \<zero>\<^bsub>P\<^esub> | q = \<zero>\<^bsub>P\<^esub>"
```
```  1095 proof -
```
```  1096   fix p q
```
```  1097   assume pq: "p \<otimes>\<^bsub>P\<^esub> q = \<zero>\<^bsub>P\<^esub>" and R: "p \<in> carrier P" "q \<in> carrier P"
```
```  1098   show "p = \<zero>\<^bsub>P\<^esub> | q = \<zero>\<^bsub>P\<^esub>"
```
```  1099   proof (rule classical)
```
```  1100     assume c: "~ (p = \<zero>\<^bsub>P\<^esub> | q = \<zero>\<^bsub>P\<^esub>)"
```
```  1101     with R have "deg R p + deg R q = deg R (p \<otimes>\<^bsub>P\<^esub> q)" by simp
```
```  1102     also from pq have "... = 0" by simp
```
```  1103     finally have "deg R p + deg R q = 0" .
```
```  1104     then have f1: "deg R p = 0 & deg R q = 0" by simp
```
```  1105     from f1 R have "p = (\<Oplus>\<^bsub>P\<^esub> i \<in> {..0}. monom P (coeff P p i) i)"
```
```  1106       by (simp only: up_repr_le)
```
```  1107     also from R have "... = monom P (coeff P p 0) 0" by simp
```
```  1108     finally have p: "p = monom P (coeff P p 0) 0" .
```
```  1109     from f1 R have "q = (\<Oplus>\<^bsub>P\<^esub> i \<in> {..0}. monom P (coeff P q i) i)"
```
```  1110       by (simp only: up_repr_le)
```
```  1111     also from R have "... = monom P (coeff P q 0) 0" by simp
```
```  1112     finally have q: "q = monom P (coeff P q 0) 0" .
```
```  1113     from R have "coeff P p 0 \<otimes> coeff P q 0 = coeff P (p \<otimes>\<^bsub>P\<^esub> q) 0" by simp
```
```  1114     also from pq have "... = \<zero>" by simp
```
```  1115     finally have "coeff P p 0 \<otimes> coeff P q 0 = \<zero>" .
```
```  1116     with R have "coeff P p 0 = \<zero> | coeff P q 0 = \<zero>"
```
```  1117       by (simp add: R.integral_iff)
```
```  1118     with p q show "p = \<zero>\<^bsub>P\<^esub> | q = \<zero>\<^bsub>P\<^esub>" by fastsimp
```
```  1119   qed
```
```  1120 qed
```
```  1121
```
```  1122 theorem (in UP_domain) UP_domain:
```
```  1123   "domain P"
```
```  1124   by (auto intro!: domainI UP_cring UP_one_not_zero UP_integral del: disjCI)
```
```  1125
```
```  1126 text {*
```
```  1127   Instantiation of theorems from @{term domain}.
```
```  1128 *}
```
```  1129
```
```  1130 (* TODO: this should be automated with an instantiation command. *)
```
```  1131
```
```  1132 lemmas (in UP_domain) UP_zero_not_one [simp] =
```
```  1133   domain.zero_not_one [OF UP_domain]
```
```  1134
```
```  1135 lemmas (in UP_domain) UP_integral_iff =
```
```  1136   domain.integral_iff [OF UP_domain]
```
```  1137
```
```  1138 lemmas (in UP_domain) UP_m_lcancel =
```
```  1139   domain.m_lcancel [OF UP_domain]
```
```  1140
```
```  1141 lemmas (in UP_domain) UP_m_rcancel =
```
```  1142   domain.m_rcancel [OF UP_domain]
```
```  1143
```
```  1144 lemma (in UP_domain) smult_integral:
```
```  1145   "[| a \<odot>\<^bsub>P\<^esub> p = \<zero>\<^bsub>P\<^esub>; a \<in> carrier R; p \<in> carrier P |] ==> a = \<zero> | p = \<zero>\<^bsub>P\<^esub>"
```
```  1146   by (simp add: monom_mult_is_smult [THEN sym] UP_integral_iff
```
```  1147     inj_on_iff [OF monom_inj, of _ "\<zero>", simplified])
```
```  1148
```
```  1149
```
```  1150 subsection {* Evaluation Homomorphism and Universal Property*}
```
```  1151
```
```  1152 (* alternative congruence rule (possibly more efficient)
```
```  1153 lemma (in abelian_monoid) finsum_cong2:
```
```  1154   "[| !!i. i \<in> A ==> f i \<in> carrier G = True; A = B;
```
```  1155   !!i. i \<in> B ==> f i = g i |] ==> finsum G f A = finsum G g B"
```
```  1156   sorry*)
```
```  1157
```
```  1158 ML_setup {*
```
```  1159   simpset_ref() := simpset() setsubgoaler asm_full_simp_tac;
```
```  1160 *}
```
```  1161
```
```  1162 theorem (in cring) diagonal_sum:
```
```  1163   "[| f \<in> {..n + m::nat} -> carrier R; g \<in> {..n + m} -> carrier R |] ==>
```
```  1164   (\<Oplus>k \<in> {..n + m}. \<Oplus>i \<in> {..k}. f i \<otimes> g (k - i)) =
```
```  1165   (\<Oplus>k \<in> {..n + m}. \<Oplus>i \<in> {..n + m - k}. f k \<otimes> g i)"
```
```  1166 proof -
```
```  1167   assume Rf: "f \<in> {..n + m} -> carrier R" and Rg: "g \<in> {..n + m} -> carrier R"
```
```  1168   {
```
```  1169     fix j
```
```  1170     have "j <= n + m ==>
```
```  1171       (\<Oplus>k \<in> {..j}. \<Oplus>i \<in> {..k}. f i \<otimes> g (k - i)) =
```
```  1172       (\<Oplus>k \<in> {..j}. \<Oplus>i \<in> {..j - k}. f k \<otimes> g i)"
```
```  1173     proof (induct j)
```
```  1174       case 0 from Rf Rg show ?case by (simp add: Pi_def)
```
```  1175     next
```
```  1176       case (Suc j)
```
```  1177       have R6: "!!i k. [| k <= j; i <= Suc j - k |] ==> g i \<in> carrier R"
```
```  1178         using Suc by (auto intro!: funcset_mem [OF Rg]) arith
```
```  1179       have R8: "!!i k. [| k <= Suc j; i <= k |] ==> g (k - i) \<in> carrier R"
```
```  1180         using Suc by (auto intro!: funcset_mem [OF Rg]) arith
```
```  1181       have R9: "!!i k. [| k <= Suc j |] ==> f k \<in> carrier R"
```
```  1182         using Suc by (auto intro!: funcset_mem [OF Rf])
```
```  1183       have R10: "!!i k. [| k <= Suc j; i <= Suc j - k |] ==> g i \<in> carrier R"
```
```  1184         using Suc by (auto intro!: funcset_mem [OF Rg]) arith
```
```  1185       have R11: "g 0 \<in> carrier R"
```
```  1186         using Suc by (auto intro!: funcset_mem [OF Rg])
```
```  1187       from Suc show ?case
```
```  1188         by (simp cong: finsum_cong add: Suc_diff_le a_ac
```
```  1189           Pi_def R6 R8 R9 R10 R11)
```
```  1190     qed
```
```  1191   }
```
```  1192   then show ?thesis by fast
```
```  1193 qed
```
```  1194
```
```  1195 lemma (in abelian_monoid) boundD_carrier:
```
```  1196   "[| bound \<zero> n f; n < m |] ==> f m \<in> carrier G"
```
```  1197   by auto
```
```  1198
```
```  1199 theorem (in cring) cauchy_product:
```
```  1200   assumes bf: "bound \<zero> n f" and bg: "bound \<zero> m g"
```
```  1201     and Rf: "f \<in> {..n} -> carrier R" and Rg: "g \<in> {..m} -> carrier R"
```
```  1202   shows "(\<Oplus>k \<in> {..n + m}. \<Oplus>i \<in> {..k}. f i \<otimes> g (k - i)) =
```
```  1203     (\<Oplus>i \<in> {..n}. f i) \<otimes> (\<Oplus>i \<in> {..m}. g i)"       (* State revese direction? *)
```
```  1204 proof -
```
```  1205   have f: "!!x. f x \<in> carrier R"
```
```  1206   proof -
```
```  1207     fix x
```
```  1208     show "f x \<in> carrier R"
```
```  1209       using Rf bf boundD_carrier by (cases "x <= n") (auto simp: Pi_def)
```
```  1210   qed
```
```  1211   have g: "!!x. g x \<in> carrier R"
```
```  1212   proof -
```
```  1213     fix x
```
```  1214     show "g x \<in> carrier R"
```
```  1215       using Rg bg boundD_carrier by (cases "x <= m") (auto simp: Pi_def)
```
```  1216   qed
```
```  1217   from f g have "(\<Oplus>k \<in> {..n + m}. \<Oplus>i \<in> {..k}. f i \<otimes> g (k - i)) =
```
```  1218       (\<Oplus>k \<in> {..n + m}. \<Oplus>i \<in> {..n + m - k}. f k \<otimes> g i)"
```
```  1219     by (simp add: diagonal_sum Pi_def)
```
```  1220   also have "... = (\<Oplus>k \<in> {..n} \<union> {n<..n + m}. \<Oplus>i \<in> {..n + m - k}. f k \<otimes> g i)"
```
```  1221     by (simp only: ivl_disj_un_one)
```
```  1222   also from f g have "... = (\<Oplus>k \<in> {..n}. \<Oplus>i \<in> {..n + m - k}. f k \<otimes> g i)"
```
```  1223     by (simp cong: finsum_cong
```
```  1224       add: bound.bound [OF bf] finsum_Un_disjoint ivl_disj_int_one Pi_def)
```
```  1225   also from f g
```
```  1226   have "... = (\<Oplus>k \<in> {..n}. \<Oplus>i \<in> {..m} \<union> {m<..n + m - k}. f k \<otimes> g i)"
```
```  1227     by (simp cong: finsum_cong add: ivl_disj_un_one le_add_diff Pi_def)
```
```  1228   also from f g have "... = (\<Oplus>k \<in> {..n}. \<Oplus>i \<in> {..m}. f k \<otimes> g i)"
```
```  1229     by (simp cong: finsum_cong
```
```  1230       add: bound.bound [OF bg] finsum_Un_disjoint ivl_disj_int_one Pi_def)
```
```  1231   also from f g have "... = (\<Oplus>i \<in> {..n}. f i) \<otimes> (\<Oplus>i \<in> {..m}. g i)"
```
```  1232     by (simp add: finsum_ldistr diagonal_sum Pi_def,
```
```  1233       simp cong: finsum_cong add: finsum_rdistr Pi_def)
```
```  1234   finally show ?thesis .
```
```  1235 qed
```
```  1236
```
```  1237 lemma (in UP_cring) const_ring_hom:
```
```  1238   "(%a. monom P a 0) \<in> ring_hom R P"
```
```  1239   by (auto intro!: ring_hom_memI intro: up_eqI simp: monom_mult_is_smult)
```
```  1240
```
```  1241 constdefs (structure S)
```
```  1242   eval :: "[('a, 'm) ring_scheme, ('b, 'n) ring_scheme,
```
```  1243            'a => 'b, 'b, nat => 'a] => 'b"
```
```  1244   "eval R S phi s == \<lambda>p \<in> carrier (UP R).
```
```  1245     \<Oplus>i \<in> {..deg R p}. phi (coeff (UP R) p i) \<otimes> s (^) i"
```
```  1246
```
```  1247 locale UP_univ_prop = ring_hom_cring R S + UP_cring R
```
```  1248
```
```  1249 lemma (in UP) eval_on_carrier:
```
```  1250   includes struct S
```
```  1251   shows  "p \<in> carrier P ==>
```
```  1252     eval R S phi s p =
```
```  1253     (\<Oplus>\<^bsub>S\<^esub> i \<in> {..deg R p}. phi (coeff P p i) \<otimes>\<^bsub>S\<^esub> s (^)\<^bsub>S\<^esub> i)"
```
```  1254   by (unfold eval_def, fold P_def) simp
```
```  1255
```
```  1256 lemma (in UP) eval_extensional:
```
```  1257   "eval R S phi s \<in> extensional (carrier P)"
```
```  1258   by (unfold eval_def, fold P_def) simp
```
```  1259
```
```  1260 theorem (in UP_univ_prop) eval_ring_hom:
```
```  1261   "s \<in> carrier S ==> eval R S h s \<in> ring_hom P S"
```
```  1262 proof (rule ring_hom_memI)
```
```  1263   fix p
```
```  1264   assume RS: "p \<in> carrier P" "s \<in> carrier S"
```
```  1265   then show "eval R S h s p \<in> carrier S"
```
```  1266     by (simp only: eval_on_carrier) (simp add: Pi_def)
```
```  1267 next
```
```  1268   fix p q
```
```  1269   assume RS: "p \<in> carrier P" "q \<in> carrier P" "s \<in> carrier S"
```
```  1270   then show "eval R S h s (p \<otimes>\<^bsub>P\<^esub> q) = eval R S h s p \<otimes>\<^bsub>S\<^esub> eval R S h s q"
```
```  1271   proof (simp only: eval_on_carrier UP_mult_closed)
```
```  1272     from RS have
```
```  1273       "(\<Oplus>\<^bsub>S\<^esub> i \<in> {..deg R (p \<otimes>\<^bsub>P\<^esub> q)}. h (coeff P (p \<otimes>\<^bsub>P\<^esub> q) i) \<otimes>\<^bsub>S\<^esub> s (^)\<^bsub>S\<^esub> i) =
```
```  1274       (\<Oplus>\<^bsub>S\<^esub> i \<in> {..deg R (p \<otimes>\<^bsub>P\<^esub> q)} \<union> {deg R (p \<otimes>\<^bsub>P\<^esub> q)<..deg R p + deg R q}.
```
```  1275         h (coeff P (p \<otimes>\<^bsub>P\<^esub> q) i) \<otimes>\<^bsub>S\<^esub> s (^)\<^bsub>S\<^esub> i)"
```
```  1276       by (simp cong: finsum_cong
```
```  1277         add: deg_aboveD finsum_Un_disjoint ivl_disj_int_one Pi_def
```
```  1278         del: coeff_mult)
```
```  1279     also from RS have "... =
```
```  1280       (\<Oplus>\<^bsub>S\<^esub> i \<in> {..deg R p + deg R q}. h (coeff P (p \<otimes>\<^bsub>P\<^esub> q) i) \<otimes>\<^bsub>S\<^esub> s (^)\<^bsub>S\<^esub> i)"
```
```  1281       by (simp only: ivl_disj_un_one deg_mult_cring)
```
```  1282     also from RS have "... =
```
```  1283       (\<Oplus>\<^bsub>S\<^esub> i \<in> {..deg R p + deg R q}.
```
```  1284          \<Oplus>\<^bsub>S\<^esub> k \<in> {..i}.
```
```  1285            h (coeff P p k) \<otimes>\<^bsub>S\<^esub> h (coeff P q (i - k)) \<otimes>\<^bsub>S\<^esub>
```
```  1286            (s (^)\<^bsub>S\<^esub> k \<otimes>\<^bsub>S\<^esub> s (^)\<^bsub>S\<^esub> (i - k)))"
```
```  1287       by (simp cong: finsum_cong add: nat_pow_mult Pi_def
```
```  1288         S.m_ac S.finsum_rdistr)
```
```  1289     also from RS have "... =
```
```  1290       (\<Oplus>\<^bsub>S\<^esub> i\<in>{..deg R p}. h (coeff P p i) \<otimes>\<^bsub>S\<^esub> s (^)\<^bsub>S\<^esub> i) \<otimes>\<^bsub>S\<^esub>
```
```  1291       (\<Oplus>\<^bsub>S\<^esub> i\<in>{..deg R q}. h (coeff P q i) \<otimes>\<^bsub>S\<^esub> s (^)\<^bsub>S\<^esub> i)"
```
```  1292       by (simp add: S.cauchy_product [THEN sym] bound.intro deg_aboveD S.m_ac
```
```  1293         Pi_def)
```
```  1294     finally show
```
```  1295       "(\<Oplus>\<^bsub>S\<^esub> i \<in> {..deg R (p \<otimes>\<^bsub>P\<^esub> q)}. h (coeff P (p \<otimes>\<^bsub>P\<^esub> q) i) \<otimes>\<^bsub>S\<^esub> s (^)\<^bsub>S\<^esub> i) =
```
```  1296       (\<Oplus>\<^bsub>S\<^esub> i \<in> {..deg R p}. h (coeff P p i) \<otimes>\<^bsub>S\<^esub> s (^)\<^bsub>S\<^esub> i) \<otimes>\<^bsub>S\<^esub>
```
```  1297       (\<Oplus>\<^bsub>S\<^esub> i \<in> {..deg R q}. h (coeff P q i) \<otimes>\<^bsub>S\<^esub> s (^)\<^bsub>S\<^esub> i)" .
```
```  1298   qed
```
```  1299 next
```
```  1300   fix p q
```
```  1301   assume RS: "p \<in> carrier P" "q \<in> carrier P" "s \<in> carrier S"
```
```  1302   then show "eval R S h s (p \<oplus>\<^bsub>P\<^esub> q) = eval R S h s p \<oplus>\<^bsub>S\<^esub> eval R S h s q"
```
```  1303   proof (simp only: eval_on_carrier UP_a_closed)
```
```  1304     from RS have
```
```  1305       "(\<Oplus>\<^bsub>S \<^esub>i\<in>{..deg R (p \<oplus>\<^bsub>P\<^esub> q)}. h (coeff P (p \<oplus>\<^bsub>P\<^esub> q) i) \<otimes>\<^bsub>S\<^esub> s (^)\<^bsub>S\<^esub> i) =
```
```  1306       (\<Oplus>\<^bsub>S \<^esub>i\<in>{..deg R (p \<oplus>\<^bsub>P\<^esub> q)} \<union> {deg R (p \<oplus>\<^bsub>P\<^esub> q)<..max (deg R p) (deg R q)}.
```
```  1307         h (coeff P (p \<oplus>\<^bsub>P\<^esub> q) i) \<otimes>\<^bsub>S\<^esub> s (^)\<^bsub>S\<^esub> i)"
```
```  1308       by (simp cong: finsum_cong
```
```  1309         add: deg_aboveD finsum_Un_disjoint ivl_disj_int_one Pi_def
```
```  1310         del: coeff_add)
```
```  1311     also from RS have "... =
```
```  1312         (\<Oplus>\<^bsub>S\<^esub> i \<in> {..max (deg R p) (deg R q)}.
```
```  1313           h (coeff P (p \<oplus>\<^bsub>P\<^esub> q) i) \<otimes>\<^bsub>S\<^esub> s (^)\<^bsub>S\<^esub> i)"
```
```  1314       by (simp add: ivl_disj_un_one)
```
```  1315     also from RS have "... =
```
```  1316       (\<Oplus>\<^bsub>S\<^esub>i\<in>{..max (deg R p) (deg R q)}. h (coeff P p i) \<otimes>\<^bsub>S\<^esub> s (^)\<^bsub>S\<^esub> i) \<oplus>\<^bsub>S\<^esub>
```
```  1317       (\<Oplus>\<^bsub>S\<^esub>i\<in>{..max (deg R p) (deg R q)}. h (coeff P q i) \<otimes>\<^bsub>S\<^esub> s (^)\<^bsub>S\<^esub> i)"
```
```  1318       by (simp cong: finsum_cong
```
```  1319         add: l_distr deg_aboveD finsum_Un_disjoint ivl_disj_int_one Pi_def)
```
```  1320     also have "... =
```
```  1321         (\<Oplus>\<^bsub>S\<^esub> i \<in> {..deg R p} \<union> {deg R p<..max (deg R p) (deg R q)}.
```
```  1322           h (coeff P p i) \<otimes>\<^bsub>S\<^esub> s (^)\<^bsub>S\<^esub> i) \<oplus>\<^bsub>S\<^esub>
```
```  1323         (\<Oplus>\<^bsub>S\<^esub> i \<in> {..deg R q} \<union> {deg R q<..max (deg R p) (deg R q)}.
```
```  1324           h (coeff P q i) \<otimes>\<^bsub>S\<^esub> s (^)\<^bsub>S\<^esub> i)"
```
```  1325       by (simp only: ivl_disj_un_one le_maxI1 le_maxI2)
```
```  1326     also from RS have "... =
```
```  1327       (\<Oplus>\<^bsub>S\<^esub> i \<in> {..deg R p}. h (coeff P p i) \<otimes>\<^bsub>S\<^esub> s (^)\<^bsub>S\<^esub> i) \<oplus>\<^bsub>S\<^esub>
```
```  1328       (\<Oplus>\<^bsub>S\<^esub> i \<in> {..deg R q}. h (coeff P q i) \<otimes>\<^bsub>S\<^esub> s (^)\<^bsub>S\<^esub> i)"
```
```  1329       by (simp cong: finsum_cong
```
```  1330         add: deg_aboveD finsum_Un_disjoint ivl_disj_int_one Pi_def)
```
```  1331     finally show
```
```  1332       "(\<Oplus>\<^bsub>S\<^esub>i \<in> {..deg R (p \<oplus>\<^bsub>P\<^esub> q)}. h (coeff P (p \<oplus>\<^bsub>P\<^esub> q) i) \<otimes>\<^bsub>S\<^esub> s (^)\<^bsub>S\<^esub> i) =
```
```  1333       (\<Oplus>\<^bsub>S\<^esub>i \<in> {..deg R p}. h (coeff P p i) \<otimes>\<^bsub>S\<^esub> s (^)\<^bsub>S\<^esub> i) \<oplus>\<^bsub>S\<^esub>
```
```  1334       (\<Oplus>\<^bsub>S\<^esub>i \<in> {..deg R q}. h (coeff P q i) \<otimes>\<^bsub>S\<^esub> s (^)\<^bsub>S\<^esub> i)" .
```
```  1335   qed
```
```  1336 next
```
```  1337   assume S: "s \<in> carrier S"
```
```  1338   then show "eval R S h s \<one>\<^bsub>P\<^esub> = \<one>\<^bsub>S\<^esub>"
```
```  1339     by (simp only: eval_on_carrier UP_one_closed) simp
```
```  1340 qed
```
```  1341
```
```  1342 text {* Instantiation of ring homomorphism lemmas. *}
```
```  1343
```
```  1344 (* TODO: again, automate with instantiation command *)
```
```  1345
```
```  1346 lemma (in UP_univ_prop) ring_hom_cring_P_S:
```
```  1347   "s \<in> carrier S ==> ring_hom_cring P S (eval R S h s)"
```
```  1348   by (fast intro!: ring_hom_cring.intro UP_cring cring.axioms prems
```
```  1349     intro: ring_hom_cring_axioms.intro eval_ring_hom)
```
```  1350
```
```  1351 (*
```
```  1352 lemma (in UP_univ_prop) UP_hom_closed [intro, simp]:
```
```  1353   "[| s \<in> carrier S; p \<in> carrier P |] ==> eval R S h s p \<in> carrier S"
```
```  1354   by (rule ring_hom_cring.hom_closed [OF ring_hom_cring_P_S])
```
```  1355
```
```  1356 lemma (in UP_univ_prop) UP_hom_mult [simp]:
```
```  1357   "[| s \<in> carrier S; p \<in> carrier P; q \<in> carrier P |] ==>
```
```  1358   eval R S h s (p \<otimes>\<^bsub>P\<^esub> q) = eval R S h s p \<otimes>\<^bsub>S\<^esub> eval R S h s q"
```
```  1359   by (rule ring_hom_cring.hom_mult [OF ring_hom_cring_P_S])
```
```  1360
```
```  1361 lemma (in UP_univ_prop) UP_hom_add [simp]:
```
```  1362   "[| s \<in> carrier S; p \<in> carrier P; q \<in> carrier P |] ==>
```
```  1363   eval R S h s (p \<oplus>\<^bsub>P\<^esub> q) = eval R S h s p \<oplus>\<^bsub>S\<^esub> eval R S h s q"
```
```  1364   by (rule ring_hom_cring.hom_add [OF ring_hom_cring_P_S])
```
```  1365
```
```  1366 lemma (in UP_univ_prop) UP_hom_one [simp]:
```
```  1367   "s \<in> carrier S ==> eval R S h s \<one>\<^bsub>P\<^esub> = \<one>\<^bsub>S\<^esub>"
```
```  1368   by (rule ring_hom_cring.hom_one [OF ring_hom_cring_P_S])
```
```  1369
```
```  1370 lemma (in UP_univ_prop) UP_hom_zero [simp]:
```
```  1371   "s \<in> carrier S ==> eval R S h s \<zero>\<^bsub>P\<^esub> = \<zero>\<^bsub>S\<^esub>"
```
```  1372   by (rule ring_hom_cring.hom_zero [OF ring_hom_cring_P_S])
```
```  1373
```
```  1374 lemma (in UP_univ_prop) UP_hom_a_inv [simp]:
```
```  1375   "[| s \<in> carrier S; p \<in> carrier P |] ==>
```
```  1376   (eval R S h s) (\<ominus>\<^bsub>P\<^esub> p) = \<ominus>\<^bsub>S\<^esub> (eval R S h s) p"
```
```  1377   by (rule ring_hom_cring.hom_a_inv [OF ring_hom_cring_P_S])
```
```  1378
```
```  1379 lemma (in UP_univ_prop) UP_hom_finsum [simp]:
```
```  1380   "[| s \<in> carrier S; finite A; f \<in> A -> carrier P |] ==>
```
```  1381   (eval R S h s) (finsum P f A) = finsum S (eval R S h s o f) A"
```
```  1382   by (rule ring_hom_cring.hom_finsum [OF ring_hom_cring_P_S])
```
```  1383
```
```  1384 lemma (in UP_univ_prop) UP_hom_finprod [simp]:
```
```  1385   "[| s \<in> carrier S; finite A; f \<in> A -> carrier P |] ==>
```
```  1386   (eval R S h s) (finprod P f A) = finprod S (eval R S h s o f) A"
```
```  1387   by (rule ring_hom_cring.hom_finprod [OF ring_hom_cring_P_S])
```
```  1388 *)
```
```  1389
```
```  1390 text {* Further properties of the evaluation homomorphism. *}
```
```  1391
```
```  1392 (* The following lemma could be proved in UP\_cring with the additional
```
```  1393    assumption that h is closed. *)
```
```  1394
```
```  1395 lemma (in UP_univ_prop) eval_const:
```
```  1396   "[| s \<in> carrier S; r \<in> carrier R |] ==> eval R S h s (monom P r 0) = h r"
```
```  1397   by (simp only: eval_on_carrier monom_closed) simp
```
```  1398
```
```  1399 text {* The following proof is complicated by the fact that in arbitrary
```
```  1400   rings one might have @{term "one R = zero R"}. *}
```
```  1401
```
```  1402 (* TODO: simplify by cases "one R = zero R" *)
```
```  1403
```
```  1404 lemma (in UP_univ_prop) eval_monom1:
```
```  1405   "s \<in> carrier S ==> eval R S h s (monom P \<one> 1) = s"
```
```  1406 proof (simp only: eval_on_carrier monom_closed R.one_closed)
```
```  1407   assume S: "s \<in> carrier S"
```
```  1408   then have
```
```  1409     "(\<Oplus>\<^bsub>S\<^esub> i\<in>{..deg R (monom P \<one> 1)}. h (coeff P (monom P \<one> 1) i) \<otimes>\<^bsub>S\<^esub> s (^)\<^bsub>S\<^esub> i) =
```
```  1410     (\<Oplus>\<^bsub>S\<^esub> i\<in>{..deg R (monom P \<one> 1)} \<union> {deg R (monom P \<one> 1)<..1}.
```
```  1411       h (coeff P (monom P \<one> 1) i) \<otimes>\<^bsub>S\<^esub> s (^)\<^bsub>S\<^esub> i)"
```
```  1412     by (simp cong: finsum_cong del: coeff_monom
```
```  1413       add: deg_aboveD finsum_Un_disjoint ivl_disj_int_one Pi_def)
```
```  1414   also have "... =
```
```  1415     (\<Oplus>\<^bsub>S\<^esub> i \<in> {..1}. h (coeff P (monom P \<one> 1) i) \<otimes>\<^bsub>S\<^esub> s (^)\<^bsub>S\<^esub> i)"
```
```  1416     by (simp only: ivl_disj_un_one deg_monom_le R.one_closed)
```
```  1417   also have "... = s"
```
```  1418   proof (cases "s = \<zero>\<^bsub>S\<^esub>")
```
```  1419     case True then show ?thesis by (simp add: Pi_def)
```
```  1420   next
```
```  1421     case False with S show ?thesis by (simp add: Pi_def)
```
```  1422   qed
```
```  1423   finally show "(\<Oplus>\<^bsub>S\<^esub> i \<in> {..deg R (monom P \<one> 1)}.
```
```  1424     h (coeff P (monom P \<one> 1) i) \<otimes>\<^bsub>S\<^esub> s (^)\<^bsub>S\<^esub> i) = s" .
```
```  1425 qed
```
```  1426
```
```  1427 lemma (in UP_cring) monom_pow:
```
```  1428   assumes R: "a \<in> carrier R"
```
```  1429   shows "(monom P a n) (^)\<^bsub>P\<^esub> m = monom P (a (^) m) (n * m)"
```
```  1430 proof (induct m)
```
```  1431   case 0 from R show ?case by simp
```
```  1432 next
```
```  1433   case Suc with R show ?case
```
```  1434     by (simp del: monom_mult add: monom_mult [THEN sym] add_commute)
```
```  1435 qed
```
```  1436
```
```  1437 lemma (in ring_hom_cring) hom_pow [simp]:
```
```  1438   "x \<in> carrier R ==> h (x (^) n) = h x (^)\<^bsub>S\<^esub> (n::nat)"
```
```  1439   by (induct n) simp_all
```
```  1440
```
```  1441 lemma (in UP_univ_prop) eval_monom:
```
```  1442   "[| s \<in> carrier S; r \<in> carrier R |] ==>
```
```  1443   eval R S h s (monom P r n) = h r \<otimes>\<^bsub>S\<^esub> s (^)\<^bsub>S\<^esub> n"
```
```  1444 proof -
```
```  1445   assume S: "s \<in> carrier S" and R: "r \<in> carrier R"
```
```  1446   from R S have "eval R S h s (monom P r n) =
```
```  1447     eval R S h s (monom P r 0 \<otimes>\<^bsub>P\<^esub> (monom P \<one> 1) (^)\<^bsub>P\<^esub> n)"
```
```  1448     by (simp del: monom_mult (* eval.hom_mult eval.hom_pow, delayed inst! *)
```
```  1449       add: monom_mult [THEN sym] monom_pow)
```
```  1450   also
```
```  1451   from ring_hom_cring_P_S [OF S] instantiate eval: ring_hom_cring
```
```  1452   from R S eval_monom1 have "... = h r \<otimes>\<^bsub>S\<^esub> s (^)\<^bsub>S\<^esub> n"
```
```  1453     by (simp add: eval_const)
```
```  1454   finally show ?thesis .
```
```  1455 qed
```
```  1456
```
```  1457 lemma (in UP_univ_prop) eval_smult:
```
```  1458   "[| s \<in> carrier S; r \<in> carrier R; p \<in> carrier P |] ==>
```
```  1459   eval R S h s (r \<odot>\<^bsub>P\<^esub> p) = h r \<otimes>\<^bsub>S\<^esub> eval R S h s p"
```
```  1460 proof -
```
```  1461   assume S: "s \<in> carrier S" and R: "r \<in> carrier R" and P: "p \<in> carrier P"
```
```  1462   from ring_hom_cring_P_S [OF S] instantiate eval: ring_hom_cring
```
```  1463   from S R P show ?thesis
```
```  1464     by (simp add: monom_mult_is_smult [THEN sym] eval_const)
```
```  1465 qed
```
```  1466
```
```  1467 lemma ring_hom_cringI:
```
```  1468   assumes "cring R"
```
```  1469     and "cring S"
```
```  1470     and "h \<in> ring_hom R S"
```
```  1471   shows "ring_hom_cring R S h"
```
```  1472   by (fast intro: ring_hom_cring.intro ring_hom_cring_axioms.intro
```
```  1473     cring.axioms prems)
```
```  1474
```
```  1475 lemma (in UP_univ_prop) UP_hom_unique:
```
```  1476   assumes Phi: "Phi \<in> ring_hom P S" "Phi (monom P \<one> (Suc 0)) = s"
```
```  1477       "!!r. r \<in> carrier R ==> Phi (monom P r 0) = h r"
```
```  1478     and Psi: "Psi \<in> ring_hom P S" "Psi (monom P \<one> (Suc 0)) = s"
```
```  1479       "!!r. r \<in> carrier R ==> Psi (monom P r 0) = h r"
```
```  1480     and S: "s \<in> carrier S" and P: "p \<in> carrier P"
```
```  1481   shows "Phi p = Psi p"
```
```  1482 proof -
```
```  1483   have Phi_hom: "ring_hom_cring P S Phi"
```
```  1484     by (auto intro: ring_hom_cringI UP_cring S.cring Phi)
```
```  1485   have Psi_hom: "ring_hom_cring P S Psi"
```
```  1486     by (auto intro: ring_hom_cringI UP_cring S.cring Psi)
```
```  1487   have "Phi p =
```
```  1488       Phi (\<Oplus>\<^bsub>P \<^esub>i \<in> {..deg R p}. monom P (coeff P p i) 0 \<otimes>\<^bsub>P\<^esub> monom P \<one> 1 (^)\<^bsub>P\<^esub> i)"
```
```  1489     by (simp add: up_repr P S monom_mult [THEN sym] monom_pow del: monom_mult)
```
```  1490   also
```
```  1491     from Phi_hom instantiate Phi: ring_hom_cring
```
```  1492     from Psi_hom instantiate Psi: ring_hom_cring
```
```  1493     have "... =
```
```  1494       Psi (\<Oplus>\<^bsub>P \<^esub>i\<in>{..deg R p}. monom P (coeff P p i) 0 \<otimes>\<^bsub>P\<^esub> monom P \<one> 1 (^)\<^bsub>P\<^esub> i)"
```
```  1495     by (simp add: Phi Psi P S Pi_def comp_def)
```
```  1496 (* Without instantiate, the following command would have been necessary.
```
```  1497     by (simp add: ring_hom_cring.hom_finsum [OF Phi_hom]
```
```  1498       ring_hom_cring.hom_mult [OF Phi_hom]
```
```  1499       ring_hom_cring.hom_pow [OF Phi_hom] Phi
```
```  1500       ring_hom_cring.hom_finsum [OF Psi_hom]
```
```  1501       ring_hom_cring.hom_mult [OF Psi_hom]
```
```  1502       ring_hom_cring.hom_pow [OF Psi_hom] Psi RS Pi_def comp_def)
```
```  1503 *)
```
```  1504   also have "... = Psi p"
```
```  1505     by (simp add: up_repr P S monom_mult [THEN sym] monom_pow del: monom_mult)
```
```  1506   finally show ?thesis .
```
```  1507 qed
```
```  1508
```
```  1509 theorem (in UP_univ_prop) UP_universal_property:
```
```  1510   "s \<in> carrier S ==>
```
```  1511   EX! Phi. Phi \<in> ring_hom P S \<inter> extensional (carrier P) &
```
```  1512     Phi (monom P \<one> 1) = s &
```
```  1513     (ALL r : carrier R. Phi (monom P r 0) = h r)"
```
```  1514   using eval_monom1
```
```  1515   apply (auto intro: eval_ring_hom eval_const eval_extensional)
```
```  1516   apply (rule extensionalityI)
```
```  1517   apply (auto intro: UP_hom_unique)
```
```  1518   done
```
```  1519
```
```  1520 subsection {* Sample application of evaluation homomorphism *}
```
```  1521
```
```  1522 lemma UP_univ_propI:
```
```  1523   assumes "cring R"
```
```  1524     and "cring S"
```
```  1525     and "h \<in> ring_hom R S"
```
```  1526   shows "UP_univ_prop R S h"
```
```  1527   by (fast intro: UP_univ_prop.intro ring_hom_cring_axioms.intro
```
```  1528     cring.axioms prems)
```
```  1529
```
```  1530 constdefs
```
```  1531   INTEG :: "int ring"
```
```  1532   "INTEG == (| carrier = UNIV, mult = op *, one = 1, zero = 0, add = op + |)"
```
```  1533
```
```  1534 lemma INTEG_cring:
```
```  1535   "cring INTEG"
```
```  1536   by (unfold INTEG_def) (auto intro!: cringI abelian_groupI comm_monoidI
```
```  1537     zadd_zminus_inverse2 zadd_zmult_distrib)
```
```  1538
```
```  1539 lemma INTEG_id_eval:
```
```  1540   "UP_univ_prop INTEG INTEG id"
```
```  1541   by (fast intro: UP_univ_propI INTEG_cring id_ring_hom)
```
```  1542
```
```  1543 text {*
```
```  1544   An instantiation mechanism would now import all theorems and lemmas
```
```  1545   valid in the context of homomorphisms between @{term INTEG} and @{term
```
```  1546   "UP INTEG"} globally.
```
```  1547 *}
```
```  1548
```
```  1549 lemma INTEG_closed [intro, simp]:
```
```  1550   "z \<in> carrier INTEG"
```
```  1551   by (unfold INTEG_def) simp
```
```  1552
```
```  1553 lemma INTEG_mult [simp]:
```
```  1554   "mult INTEG z w = z * w"
```
```  1555   by (unfold INTEG_def) simp
```
```  1556
```
```  1557 lemma INTEG_pow [simp]:
```
```  1558   "pow INTEG z n = z ^ n"
```
```  1559   by (induct n) (simp_all add: INTEG_def nat_pow_def)
```
```  1560
```
```  1561 lemma "eval INTEG INTEG id 10 (monom (UP INTEG) 5 2) = 500"
```
```  1562   by (simp add: UP_univ_prop.eval_monom [OF INTEG_id_eval])
```
```  1563
```
```  1564 end
```