src/HOL/Decision_Procs/Reflected_Multivariate_Polynomial.thy
 author krauss Mon Feb 21 23:14:36 2011 +0100 (2011-02-21) changeset 41814 3848eb635eab parent 41813 4eb43410d2fa child 41815 9a0cacbcd825 permissions -rw-r--r--
modernized specification; curried
```     1 (*  Title:      HOL/Decision_Procs/Reflected_Multivariate_Polynomial.thy
```
```     2     Author:     Amine Chaieb
```
```     3 *)
```
```     4
```
```     5 header {* Implementation and verification of multivariate polynomials *}
```
```     6
```
```     7 theory Reflected_Multivariate_Polynomial
```
```     8 imports Complex_Main "~~/src/HOL/Library/Abstract_Rat" Polynomial_List
```
```     9 begin
```
```    10
```
```    11   (* Implementation *)
```
```    12
```
```    13 subsection{* Datatype of polynomial expressions *}
```
```    14
```
```    15 datatype poly = C Num| Bound nat| Add poly poly|Sub poly poly
```
```    16   | Mul poly poly| Neg poly| Pw poly nat| CN poly nat poly
```
```    17
```
```    18 abbreviation poly_0 :: "poly" ("0\<^sub>p") where "0\<^sub>p \<equiv> C (0\<^sub>N)"
```
```    19 abbreviation poly_p :: "int \<Rightarrow> poly" ("_\<^sub>p") where "i\<^sub>p \<equiv> C (i\<^sub>N)"
```
```    20
```
```    21 subsection{* Boundedness, substitution and all that *}
```
```    22 primrec polysize:: "poly \<Rightarrow> nat" where
```
```    23   "polysize (C c) = 1"
```
```    24 | "polysize (Bound n) = 1"
```
```    25 | "polysize (Neg p) = 1 + polysize p"
```
```    26 | "polysize (Add p q) = 1 + polysize p + polysize q"
```
```    27 | "polysize (Sub p q) = 1 + polysize p + polysize q"
```
```    28 | "polysize (Mul p q) = 1 + polysize p + polysize q"
```
```    29 | "polysize (Pw p n) = 1 + polysize p"
```
```    30 | "polysize (CN c n p) = 4 + polysize c + polysize p"
```
```    31
```
```    32 primrec polybound0:: "poly \<Rightarrow> bool" (* a poly is INDEPENDENT of Bound 0 *) where
```
```    33   "polybound0 (C c) = True"
```
```    34 | "polybound0 (Bound n) = (n>0)"
```
```    35 | "polybound0 (Neg a) = polybound0 a"
```
```    36 | "polybound0 (Add a b) = (polybound0 a \<and> polybound0 b)"
```
```    37 | "polybound0 (Sub a b) = (polybound0 a \<and> polybound0 b)"
```
```    38 | "polybound0 (Mul a b) = (polybound0 a \<and> polybound0 b)"
```
```    39 | "polybound0 (Pw p n) = (polybound0 p)"
```
```    40 | "polybound0 (CN c n p) = (n \<noteq> 0 \<and> polybound0 c \<and> polybound0 p)"
```
```    41
```
```    42 primrec polysubst0:: "poly \<Rightarrow> poly \<Rightarrow> poly" (* substitute a poly into a poly for Bound 0 *) where
```
```    43   "polysubst0 t (C c) = (C c)"
```
```    44 | "polysubst0 t (Bound n) = (if n=0 then t else Bound n)"
```
```    45 | "polysubst0 t (Neg a) = Neg (polysubst0 t a)"
```
```    46 | "polysubst0 t (Add a b) = Add (polysubst0 t a) (polysubst0 t b)"
```
```    47 | "polysubst0 t (Sub a b) = Sub (polysubst0 t a) (polysubst0 t b)"
```
```    48 | "polysubst0 t (Mul a b) = Mul (polysubst0 t a) (polysubst0 t b)"
```
```    49 | "polysubst0 t (Pw p n) = Pw (polysubst0 t p) n"
```
```    50 | "polysubst0 t (CN c n p) = (if n=0 then Add (polysubst0 t c) (Mul t (polysubst0 t p))
```
```    51                              else CN (polysubst0 t c) n (polysubst0 t p))"
```
```    52
```
```    53 fun decrpoly:: "poly \<Rightarrow> poly"
```
```    54 where
```
```    55   "decrpoly (Bound n) = Bound (n - 1)"
```
```    56 | "decrpoly (Neg a) = Neg (decrpoly a)"
```
```    57 | "decrpoly (Add a b) = Add (decrpoly a) (decrpoly b)"
```
```    58 | "decrpoly (Sub a b) = Sub (decrpoly a) (decrpoly b)"
```
```    59 | "decrpoly (Mul a b) = Mul (decrpoly a) (decrpoly b)"
```
```    60 | "decrpoly (Pw p n) = Pw (decrpoly p) n"
```
```    61 | "decrpoly (CN c n p) = CN (decrpoly c) (n - 1) (decrpoly p)"
```
```    62 | "decrpoly a = a"
```
```    63
```
```    64 subsection{* Degrees and heads and coefficients *}
```
```    65
```
```    66 fun degree:: "poly \<Rightarrow> nat"
```
```    67 where
```
```    68   "degree (CN c 0 p) = 1 + degree p"
```
```    69 | "degree p = 0"
```
```    70
```
```    71 fun head:: "poly \<Rightarrow> poly"
```
```    72 where
```
```    73   "head (CN c 0 p) = head p"
```
```    74 | "head p = p"
```
```    75
```
```    76 (* More general notions of degree and head *)
```
```    77 fun degreen:: "poly \<Rightarrow> nat \<Rightarrow> nat"
```
```    78 where
```
```    79   "degreen (CN c n p) = (\<lambda>m. if n=m then 1 + degreen p n else 0)"
```
```    80  |"degreen p = (\<lambda>m. 0)"
```
```    81
```
```    82 fun headn:: "poly \<Rightarrow> nat \<Rightarrow> poly"
```
```    83 where
```
```    84   "headn (CN c n p) = (\<lambda>m. if n \<le> m then headn p m else CN c n p)"
```
```    85 | "headn p = (\<lambda>m. p)"
```
```    86
```
```    87 fun coefficients:: "poly \<Rightarrow> poly list"
```
```    88 where
```
```    89   "coefficients (CN c 0 p) = c#(coefficients p)"
```
```    90 | "coefficients p = [p]"
```
```    91
```
```    92 fun isconstant:: "poly \<Rightarrow> bool"
```
```    93 where
```
```    94   "isconstant (CN c 0 p) = False"
```
```    95 | "isconstant p = True"
```
```    96
```
```    97 fun behead:: "poly \<Rightarrow> poly"
```
```    98 where
```
```    99   "behead (CN c 0 p) = (let p' = behead p in if p' = 0\<^sub>p then c else CN c 0 p')"
```
```   100 | "behead p = 0\<^sub>p"
```
```   101
```
```   102 fun headconst:: "poly \<Rightarrow> Num"
```
```   103 where
```
```   104   "headconst (CN c n p) = headconst p"
```
```   105 | "headconst (C n) = n"
```
```   106
```
```   107 subsection{* Operations for normalization *}
```
```   108
```
```   109
```
```   110 declare if_cong[fundef_cong del]
```
```   111 declare let_cong[fundef_cong del]
```
```   112
```
```   113 fun polyadd :: "poly \<Rightarrow> poly \<Rightarrow> poly" (infixl "+\<^sub>p" 60)
```
```   114 where
```
```   115   "polyadd (C c) (C c') = C (c+\<^sub>Nc')"
```
```   116 |  "polyadd (C c) (CN c' n' p') = CN (polyadd (C c) c') n' p'"
```
```   117 | "polyadd (CN c n p) (C c') = CN (polyadd c (C c')) n p"
```
```   118 | "polyadd (CN c n p) (CN c' n' p') =
```
```   119     (if n < n' then CN (polyadd c (CN c' n' p')) n p
```
```   120      else if n'<n then CN (polyadd (CN c n p) c') n' p'
```
```   121      else (let cc' = polyadd c c' ;
```
```   122                pp' = polyadd p p'
```
```   123            in (if pp' = 0\<^sub>p then cc' else CN cc' n pp')))"
```
```   124 | "polyadd a b = Add a b"
```
```   125
```
```   126
```
```   127 fun polyneg :: "poly \<Rightarrow> poly" ("~\<^sub>p")
```
```   128 where
```
```   129   "polyneg (C c) = C (~\<^sub>N c)"
```
```   130 | "polyneg (CN c n p) = CN (polyneg c) n (polyneg p)"
```
```   131 | "polyneg a = Neg a"
```
```   132
```
```   133 definition polysub :: "poly \<Rightarrow> poly \<Rightarrow> poly" (infixl "-\<^sub>p" 60)
```
```   134 where
```
```   135   "p -\<^sub>p q = polyadd p (polyneg q)"
```
```   136
```
```   137 fun polymul :: "poly \<Rightarrow> poly \<Rightarrow> poly" (infixl "*\<^sub>p" 60)
```
```   138 where
```
```   139   "polymul (C c) (C c') = C (c*\<^sub>Nc')"
```
```   140 | "polymul (C c) (CN c' n' p') =
```
```   141       (if c = 0\<^sub>N then 0\<^sub>p else CN (polymul (C c) c') n' (polymul (C c) p'))"
```
```   142 | "polymul (CN c n p) (C c') =
```
```   143       (if c' = 0\<^sub>N  then 0\<^sub>p else CN (polymul c (C c')) n (polymul p (C c')))"
```
```   144 | "polymul (CN c n p) (CN c' n' p') =
```
```   145   (if n<n' then CN (polymul c (CN c' n' p')) n (polymul p (CN c' n' p'))
```
```   146   else if n' < n
```
```   147   then CN (polymul (CN c n p) c') n' (polymul (CN c n p) p')
```
```   148   else polyadd (polymul (CN c n p) c') (CN 0\<^sub>p n' (polymul (CN c n p) p')))"
```
```   149 | "polymul a b = Mul a b"
```
```   150
```
```   151 declare if_cong[fundef_cong]
```
```   152 declare let_cong[fundef_cong]
```
```   153
```
```   154 fun polypow :: "nat \<Rightarrow> poly \<Rightarrow> poly"
```
```   155 where
```
```   156   "polypow 0 = (\<lambda>p. 1\<^sub>p)"
```
```   157 | "polypow n = (\<lambda>p. let q = polypow (n div 2) p ; d = polymul q q in
```
```   158                     if even n then d else polymul p d)"
```
```   159
```
```   160 abbreviation poly_pow :: "poly \<Rightarrow> nat \<Rightarrow> poly" (infixl "^\<^sub>p" 60)
```
```   161   where "a ^\<^sub>p k \<equiv> polypow k a"
```
```   162
```
```   163 function polynate :: "poly \<Rightarrow> poly"
```
```   164 where
```
```   165   "polynate (Bound n) = CN 0\<^sub>p n 1\<^sub>p"
```
```   166 | "polynate (Add p q) = (polynate p +\<^sub>p polynate q)"
```
```   167 | "polynate (Sub p q) = (polynate p -\<^sub>p polynate q)"
```
```   168 | "polynate (Mul p q) = (polynate p *\<^sub>p polynate q)"
```
```   169 | "polynate (Neg p) = (~\<^sub>p (polynate p))"
```
```   170 | "polynate (Pw p n) = ((polynate p) ^\<^sub>p n)"
```
```   171 | "polynate (CN c n p) = polynate (Add c (Mul (Bound n) p))"
```
```   172 | "polynate (C c) = C (normNum c)"
```
```   173 by pat_completeness auto
```
```   174 termination by (relation "measure polysize") auto
```
```   175
```
```   176 fun poly_cmul :: "Num \<Rightarrow> poly \<Rightarrow> poly" where
```
```   177   "poly_cmul y (C x) = C (y *\<^sub>N x)"
```
```   178 | "poly_cmul y (CN c n p) = CN (poly_cmul y c) n (poly_cmul y p)"
```
```   179 | "poly_cmul y p = C y *\<^sub>p p"
```
```   180
```
```   181 definition monic :: "poly \<Rightarrow> (poly \<times> bool)" where
```
```   182   "monic p \<equiv> (let h = headconst p in if h = 0\<^sub>N then (p,False) else ((C (Ninv h)) *\<^sub>p p, 0>\<^sub>N h))"
```
```   183
```
```   184 subsection{* Pseudo-division *}
```
```   185
```
```   186 definition shift1 :: "poly \<Rightarrow> poly" where
```
```   187   "shift1 p \<equiv> CN 0\<^sub>p 0 p"
```
```   188
```
```   189 abbreviation funpow :: "nat \<Rightarrow> ('a \<Rightarrow> 'a) \<Rightarrow> ('a \<Rightarrow> 'a)" where
```
```   190   "funpow \<equiv> compow"
```
```   191
```
```   192 partial_function (tailrec) polydivide_aux :: "poly \<Rightarrow> nat \<Rightarrow> poly \<Rightarrow> nat \<Rightarrow> poly \<Rightarrow> nat \<times> poly"
```
```   193   where
```
```   194   "polydivide_aux a n p k s =
```
```   195   (if s = 0\<^sub>p then (k,s)
```
```   196   else (let b = head s; m = degree s in
```
```   197   (if m < n then (k,s) else
```
```   198   (let p'= funpow (m - n) shift1 p in
```
```   199   (if a = b then polydivide_aux a n p k (s -\<^sub>p p')
```
```   200   else polydivide_aux a n p (Suc k) ((a *\<^sub>p s) -\<^sub>p (b *\<^sub>p p')))))))"
```
```   201
```
```   202 definition polydivide :: "poly \<Rightarrow> poly \<Rightarrow> (nat \<times> poly)" where
```
```   203   "polydivide s p \<equiv> polydivide_aux (head p) (degree p) p 0 s"
```
```   204
```
```   205 fun poly_deriv_aux :: "nat \<Rightarrow> poly \<Rightarrow> poly" where
```
```   206   "poly_deriv_aux n (CN c 0 p) = CN (poly_cmul ((int n)\<^sub>N) c) 0 (poly_deriv_aux (n + 1) p)"
```
```   207 | "poly_deriv_aux n p = poly_cmul ((int n)\<^sub>N) p"
```
```   208
```
```   209 fun poly_deriv :: "poly \<Rightarrow> poly" where
```
```   210   "poly_deriv (CN c 0 p) = poly_deriv_aux 1 p"
```
```   211 | "poly_deriv p = 0\<^sub>p"
```
```   212
```
```   213   (* Verification *)
```
```   214 lemma nth_pos2[simp]: "0 < n \<Longrightarrow> (x#xs) ! n = xs ! (n - 1)"
```
```   215 using Nat.gr0_conv_Suc
```
```   216 by clarsimp
```
```   217
```
```   218 subsection{* Semantics of the polynomial representation *}
```
```   219
```
```   220 primrec Ipoly :: "'a list \<Rightarrow> poly \<Rightarrow> 'a::{field_char_0, field_inverse_zero, power}" where
```
```   221   "Ipoly bs (C c) = INum c"
```
```   222 | "Ipoly bs (Bound n) = bs!n"
```
```   223 | "Ipoly bs (Neg a) = - Ipoly bs a"
```
```   224 | "Ipoly bs (Add a b) = Ipoly bs a + Ipoly bs b"
```
```   225 | "Ipoly bs (Sub a b) = Ipoly bs a - Ipoly bs b"
```
```   226 | "Ipoly bs (Mul a b) = Ipoly bs a * Ipoly bs b"
```
```   227 | "Ipoly bs (Pw t n) = (Ipoly bs t) ^ n"
```
```   228 | "Ipoly bs (CN c n p) = (Ipoly bs c) + (bs!n)*(Ipoly bs p)"
```
```   229
```
```   230 abbreviation
```
```   231   Ipoly_syntax :: "poly \<Rightarrow> 'a list \<Rightarrow>'a::{field_char_0, field_inverse_zero, power}" ("\<lparr>_\<rparr>\<^sub>p\<^bsup>_\<^esup>")
```
```   232   where "\<lparr>p\<rparr>\<^sub>p\<^bsup>bs\<^esup> \<equiv> Ipoly bs p"
```
```   233
```
```   234 lemma Ipoly_CInt: "Ipoly bs (C (i,1)) = of_int i"
```
```   235   by (simp add: INum_def)
```
```   236 lemma Ipoly_CRat: "Ipoly bs (C (i, j)) = of_int i / of_int j"
```
```   237   by (simp  add: INum_def)
```
```   238
```
```   239 lemmas RIpoly_eqs = Ipoly.simps(2-7) Ipoly_CInt Ipoly_CRat
```
```   240
```
```   241 subsection {* Normal form and normalization *}
```
```   242
```
```   243 fun isnpolyh:: "poly \<Rightarrow> nat \<Rightarrow> bool"
```
```   244 where
```
```   245   "isnpolyh (C c) = (\<lambda>k. isnormNum c)"
```
```   246 | "isnpolyh (CN c n p) = (\<lambda>k. n \<ge> k \<and> (isnpolyh c (Suc n)) \<and> (isnpolyh p n) \<and> (p \<noteq> 0\<^sub>p))"
```
```   247 | "isnpolyh p = (\<lambda>k. False)"
```
```   248
```
```   249 lemma isnpolyh_mono: "\<lbrakk>n' \<le> n ; isnpolyh p n\<rbrakk> \<Longrightarrow> isnpolyh p n'"
```
```   250 by (induct p rule: isnpolyh.induct, auto)
```
```   251
```
```   252 definition isnpoly :: "poly \<Rightarrow> bool" where
```
```   253   "isnpoly p \<equiv> isnpolyh p 0"
```
```   254
```
```   255 text{* polyadd preserves normal forms *}
```
```   256
```
```   257 lemma polyadd_normh: "\<lbrakk>isnpolyh p n0 ; isnpolyh q n1\<rbrakk>
```
```   258       \<Longrightarrow> isnpolyh (polyadd p q) (min n0 n1)"
```
```   259 proof(induct p q arbitrary: n0 n1 rule: polyadd.induct)
```
```   260   case (2 ab c' n' p' n0 n1)
```
```   261   from prems have  th1: "isnpolyh (C ab) (Suc n')" by simp
```
```   262   from prems(3) have th2: "isnpolyh c' (Suc n')"  and nplen1: "n' \<ge> n1" by simp_all
```
```   263   with isnpolyh_mono have cp: "isnpolyh c' (Suc n')" by simp
```
```   264   with prems(1)[OF th1 th2] have th3:"isnpolyh (C ab +\<^sub>p c') (Suc n')" by simp
```
```   265   from nplen1 have n01len1: "min n0 n1 \<le> n'" by simp
```
```   266   thus ?case using prems th3 by simp
```
```   267 next
```
```   268   case (3 c' n' p' ab n1 n0)
```
```   269   from prems have  th1: "isnpolyh (C ab) (Suc n')" by simp
```
```   270   from prems(2) have th2: "isnpolyh c' (Suc n')"  and nplen1: "n' \<ge> n1" by simp_all
```
```   271   with isnpolyh_mono have cp: "isnpolyh c' (Suc n')" by simp
```
```   272   with prems(1)[OF th2 th1] have th3:"isnpolyh (c' +\<^sub>p C ab) (Suc n')" by simp
```
```   273   from nplen1 have n01len1: "min n0 n1 \<le> n'" by simp
```
```   274   thus ?case using prems th3 by simp
```
```   275 next
```
```   276   case (4 c n p c' n' p' n0 n1)
```
```   277   hence nc: "isnpolyh c (Suc n)" and np: "isnpolyh p n" by simp_all
```
```   278   from prems have nc': "isnpolyh c' (Suc n')" and np': "isnpolyh p' n'" by simp_all
```
```   279   from prems have ngen0: "n \<ge> n0" by simp
```
```   280   from prems have n'gen1: "n' \<ge> n1" by simp
```
```   281   have "n < n' \<or> n' < n \<or> n = n'" by auto
```
```   282   moreover {assume eq: "n = n'"
```
```   283     with "4.hyps"(3)[OF nc nc']
```
```   284     have ncc':"isnpolyh (c +\<^sub>p c') (Suc n)" by auto
```
```   285     hence ncc'n01: "isnpolyh (c +\<^sub>p c') (min n0 n1)"
```
```   286       using isnpolyh_mono[where n'="min n0 n1" and n="Suc n"] ngen0 n'gen1 by auto
```
```   287     from eq "4.hyps"(4)[OF np np'] have npp': "isnpolyh (p +\<^sub>p p') n" by simp
```
```   288     have minle: "min n0 n1 \<le> n'" using ngen0 n'gen1 eq by simp
```
```   289     from minle npp' ncc'n01 prems ngen0 n'gen1 ncc' have ?case by (simp add: Let_def)}
```
```   290   moreover {assume lt: "n < n'"
```
```   291     have "min n0 n1 \<le> n0" by simp
```
```   292     with prems have th1:"min n0 n1 \<le> n" by auto
```
```   293     from prems have th21: "isnpolyh c (Suc n)" by simp
```
```   294     from prems have th22: "isnpolyh (CN c' n' p') n'" by simp
```
```   295     from lt have th23: "min (Suc n) n' = Suc n" by arith
```
```   296     from "4.hyps"(1)[OF th21 th22]
```
```   297     have "isnpolyh (polyadd c (CN c' n' p')) (Suc n)" using th23 by simp
```
```   298     with prems th1 have ?case by simp }
```
```   299   moreover {assume gt: "n' < n" hence gt': "n' < n \<and> \<not> n < n'" by simp
```
```   300     have "min n0 n1 \<le> n1"  by simp
```
```   301     with prems have th1:"min n0 n1 \<le> n'" by auto
```
```   302     from prems have th21: "isnpolyh c' (Suc n')" by simp_all
```
```   303     from prems have th22: "isnpolyh (CN c n p) n" by simp
```
```   304     from gt have th23: "min n (Suc n') = Suc n'" by arith
```
```   305     from "4.hyps"(2)[OF th22 th21]
```
```   306     have "isnpolyh (polyadd (CN c n p) c') (Suc n')" using th23 by simp
```
```   307     with prems th1 have ?case by simp}
```
```   308       ultimately show ?case by blast
```
```   309 qed auto
```
```   310
```
```   311 lemma polyadd[simp]: "Ipoly bs (polyadd p q) = Ipoly bs p + Ipoly bs q"
```
```   312 by (induct p q rule: polyadd.induct, auto simp add: Let_def field_simps right_distrib[symmetric] simp del: right_distrib)
```
```   313
```
```   314 lemma polyadd_norm: "\<lbrakk> isnpoly p ; isnpoly q\<rbrakk> \<Longrightarrow> isnpoly (polyadd p q)"
```
```   315   using polyadd_normh[of "p" "0" "q" "0"] isnpoly_def by simp
```
```   316
```
```   317 text{* The degree of addition and other general lemmas needed for the normal form of polymul *}
```
```   318
```
```   319 lemma polyadd_different_degreen:
```
```   320   "\<lbrakk>isnpolyh p n0 ; isnpolyh q n1; degreen p m \<noteq> degreen q m ; m \<le> min n0 n1\<rbrakk> \<Longrightarrow>
```
```   321   degreen (polyadd p q) m = max (degreen p m) (degreen q m)"
```
```   322 proof (induct p q arbitrary: m n0 n1 rule: polyadd.induct)
```
```   323   case (4 c n p c' n' p' m n0 n1)
```
```   324   have "n' = n \<or> n < n' \<or> n' < n" by arith
```
```   325   thus ?case
```
```   326   proof (elim disjE)
```
```   327     assume [simp]: "n' = n"
```
```   328     from 4(4)[of n n m] 4(3)[of "Suc n" "Suc n" m] 4(5-7)
```
```   329     show ?thesis by (auto simp: Let_def)
```
```   330   next
```
```   331     assume "n < n'"
```
```   332     with 4 show ?thesis by auto
```
```   333   next
```
```   334     assume "n' < n"
```
```   335     with 4 show ?thesis by auto
```
```   336   qed
```
```   337 qed auto
```
```   338
```
```   339 lemma headnz[simp]: "\<lbrakk>isnpolyh p n ; p \<noteq> 0\<^sub>p\<rbrakk> \<Longrightarrow> headn p m \<noteq> 0\<^sub>p"
```
```   340   by (induct p arbitrary: n rule: headn.induct, auto)
```
```   341 lemma degree_isnpolyh_Suc[simp]: "isnpolyh p (Suc n) \<Longrightarrow> degree p = 0"
```
```   342   by (induct p arbitrary: n rule: degree.induct, auto)
```
```   343 lemma degreen_0[simp]: "isnpolyh p n \<Longrightarrow> m < n \<Longrightarrow> degreen p m = 0"
```
```   344   by (induct p arbitrary: n rule: degreen.induct, auto)
```
```   345
```
```   346 lemma degree_isnpolyh_Suc': "n > 0 \<Longrightarrow> isnpolyh p n \<Longrightarrow> degree p = 0"
```
```   347   by (induct p arbitrary: n rule: degree.induct, auto)
```
```   348
```
```   349 lemma degree_npolyhCN[simp]: "isnpolyh (CN c n p) n0 \<Longrightarrow> degree c = 0"
```
```   350   using degree_isnpolyh_Suc by auto
```
```   351 lemma degreen_npolyhCN[simp]: "isnpolyh (CN c n p) n0 \<Longrightarrow> degreen c n = 0"
```
```   352   using degreen_0 by auto
```
```   353
```
```   354
```
```   355 lemma degreen_polyadd:
```
```   356   assumes np: "isnpolyh p n0" and nq: "isnpolyh q n1" and m: "m \<le> max n0 n1"
```
```   357   shows "degreen (p +\<^sub>p q) m \<le> max (degreen p m) (degreen q m)"
```
```   358   using np nq m
```
```   359 proof (induct p q arbitrary: n0 n1 m rule: polyadd.induct)
```
```   360   case (2 c c' n' p' n0 n1) thus ?case  by (cases n', simp_all)
```
```   361 next
```
```   362   case (3 c n p c' n0 n1) thus ?case by (cases n, auto)
```
```   363 next
```
```   364   case (4 c n p c' n' p' n0 n1 m)
```
```   365   have "n' = n \<or> n < n' \<or> n' < n" by arith
```
```   366   thus ?case
```
```   367   proof (elim disjE)
```
```   368     assume [simp]: "n' = n"
```
```   369     from 4(4)[of n n m] 4(3)[of "Suc n" "Suc n" m] 4(5-7)
```
```   370     show ?thesis by (auto simp: Let_def)
```
```   371   qed simp_all
```
```   372 qed auto
```
```   373
```
```   374 lemma polyadd_eq_const_degreen: "\<lbrakk> isnpolyh p n0 ; isnpolyh q n1 ; polyadd p q = C c\<rbrakk>
```
```   375   \<Longrightarrow> degreen p m = degreen q m"
```
```   376 proof (induct p q arbitrary: m n0 n1 c rule: polyadd.induct)
```
```   377   case (4 c n p c' n' p' m n0 n1 x)
```
```   378   {assume nn': "n' < n" hence ?case using prems by simp}
```
```   379   moreover
```
```   380   {assume nn':"\<not> n' < n" hence "n < n' \<or> n = n'" by arith
```
```   381     moreover {assume "n < n'" with prems have ?case by simp }
```
```   382     moreover {assume eq: "n = n'" hence ?case using prems
```
```   383         apply (cases "p +\<^sub>p p' = 0\<^sub>p")
```
```   384         apply (auto simp add: Let_def)
```
```   385         by blast
```
```   386       }
```
```   387     ultimately have ?case by blast}
```
```   388   ultimately show ?case by blast
```
```   389 qed simp_all
```
```   390
```
```   391 lemma polymul_properties:
```
```   392   assumes "SORT_CONSTRAINT('a::{field_char_0, field_inverse_zero})"
```
```   393   and np: "isnpolyh p n0" and nq: "isnpolyh q n1" and m: "m \<le> min n0 n1"
```
```   394   shows "isnpolyh (p *\<^sub>p q) (min n0 n1)"
```
```   395   and "(p *\<^sub>p q = 0\<^sub>p) = (p = 0\<^sub>p \<or> q = 0\<^sub>p)"
```
```   396   and "degreen (p *\<^sub>p q) m = (if (p = 0\<^sub>p \<or> q = 0\<^sub>p) then 0
```
```   397                              else degreen p m + degreen q m)"
```
```   398   using np nq m
```
```   399 proof(induct p q arbitrary: n0 n1 m rule: polymul.induct)
```
```   400   case (2 c c' n' p')
```
```   401   { case (1 n0 n1)
```
```   402     with "2.hyps"(4-6)[of n' n' n']
```
```   403       and "2.hyps"(1-3)[of "Suc n'" "Suc n'" n']
```
```   404     show ?case by (auto simp add: min_def)
```
```   405   next
```
```   406     case (2 n0 n1) thus ?case by auto
```
```   407   next
```
```   408     case (3 n0 n1) thus ?case  using "2.hyps" by auto }
```
```   409 next
```
```   410   case (3 c n p c')
```
```   411   { case (1 n0 n1)
```
```   412     with "3.hyps"(4-6)[of n n n]
```
```   413       "3.hyps"(1-3)[of "Suc n" "Suc n" n]
```
```   414     show ?case by (auto simp add: min_def)
```
```   415   next
```
```   416     case (2 n0 n1) thus ?case by auto
```
```   417   next
```
```   418     case (3 n0 n1) thus ?case  using "3.hyps" by auto }
```
```   419 next
```
```   420   case (4 c n p c' n' p')
```
```   421   let ?cnp = "CN c n p" let ?cnp' = "CN c' n' p'"
```
```   422     {
```
```   423       case (1 n0 n1)
```
```   424       hence cnp: "isnpolyh ?cnp n" and cnp': "isnpolyh ?cnp' n'"
```
```   425         and np: "isnpolyh p n" and nc: "isnpolyh c (Suc n)"
```
```   426         and np': "isnpolyh p' n'" and nc': "isnpolyh c' (Suc n')"
```
```   427         and nn0: "n \<ge> n0" and nn1:"n' \<ge> n1"
```
```   428         by simp_all
```
```   429       { assume "n < n'"
```
```   430         with "4.hyps"(4-5)[OF np cnp', of n]
```
```   431           "4.hyps"(1)[OF nc cnp', of n] nn0 cnp
```
```   432         have ?case by (simp add: min_def)
```
```   433       } moreover {
```
```   434         assume "n' < n"
```
```   435         with "4.hyps"(16-17)[OF cnp np', of "n'"]
```
```   436           "4.hyps"(13)[OF cnp nc', of "Suc n'"] nn1 cnp'
```
```   437         have ?case
```
```   438           by (cases "Suc n' = n", simp_all add: min_def)
```
```   439       } moreover {
```
```   440         assume "n' = n"
```
```   441         with "4.hyps"(16-17)[OF cnp np', of n]
```
```   442           "4.hyps"(13)[OF cnp nc', of n] cnp cnp' nn1 nn0
```
```   443         have ?case
```
```   444           apply (auto intro!: polyadd_normh)
```
```   445           apply (simp_all add: min_def isnpolyh_mono[OF nn0])
```
```   446           done
```
```   447       }
```
```   448       ultimately show ?case by arith
```
```   449     next
```
```   450       fix n0 n1 m
```
```   451       assume np: "isnpolyh ?cnp n0" and np':"isnpolyh ?cnp' n1"
```
```   452       and m: "m \<le> min n0 n1"
```
```   453       let ?d = "degreen (?cnp *\<^sub>p ?cnp') m"
```
```   454       let ?d1 = "degreen ?cnp m"
```
```   455       let ?d2 = "degreen ?cnp' m"
```
```   456       let ?eq = "?d = (if ?cnp = 0\<^sub>p \<or> ?cnp' = 0\<^sub>p then 0  else ?d1 + ?d2)"
```
```   457       have "n'<n \<or> n < n' \<or> n' = n" by auto
```
```   458       moreover
```
```   459       {assume "n' < n \<or> n < n'"
```
```   460         with "4.hyps"(3,6,18) np np' m
```
```   461         have ?eq by auto }
```
```   462       moreover
```
```   463       {assume nn': "n' = n" hence nn:"\<not> n' < n \<and> \<not> n < n'" by arith
```
```   464         from "4.hyps"(16,18)[of n n' n]
```
```   465           "4.hyps"(13,14)[of n "Suc n'" n]
```
```   466           np np' nn'
```
```   467         have norm: "isnpolyh ?cnp n" "isnpolyh c' (Suc n)" "isnpolyh (?cnp *\<^sub>p c') n"
```
```   468           "isnpolyh p' n" "isnpolyh (?cnp *\<^sub>p p') n" "isnpolyh (CN 0\<^sub>p n (CN c n p *\<^sub>p p')) n"
```
```   469           "(?cnp *\<^sub>p c' = 0\<^sub>p) = (c' = 0\<^sub>p)"
```
```   470           "?cnp *\<^sub>p p' \<noteq> 0\<^sub>p" by (auto simp add: min_def)
```
```   471         {assume mn: "m = n"
```
```   472           from "4.hyps"(17,18)[OF norm(1,4), of n]
```
```   473             "4.hyps"(13,15)[OF norm(1,2), of n] norm nn' mn
```
```   474           have degs:  "degreen (?cnp *\<^sub>p c') n =
```
```   475             (if c'=0\<^sub>p then 0 else ?d1 + degreen c' n)"
```
```   476             "degreen (?cnp *\<^sub>p p') n = ?d1  + degreen p' n" by (simp_all add: min_def)
```
```   477           from degs norm
```
```   478           have th1: "degreen(?cnp *\<^sub>p c') n < degreen (CN 0\<^sub>p n (?cnp *\<^sub>p p')) n" by simp
```
```   479           hence neq: "degreen (?cnp *\<^sub>p c') n \<noteq> degreen (CN 0\<^sub>p n (?cnp *\<^sub>p p')) n"
```
```   480             by simp
```
```   481           have nmin: "n \<le> min n n" by (simp add: min_def)
```
```   482           from polyadd_different_degreen[OF norm(3,6) neq nmin] th1
```
```   483           have deg: "degreen (CN c n p *\<^sub>p c' +\<^sub>p CN 0\<^sub>p n (CN c n p *\<^sub>p p')) n = degreen (CN 0\<^sub>p n (CN c n p *\<^sub>p p')) n" by simp
```
```   484           from "4.hyps"(16-18)[OF norm(1,4), of n]
```
```   485             "4.hyps"(13-15)[OF norm(1,2), of n]
```
```   486             mn norm m nn' deg
```
```   487           have ?eq by simp}
```
```   488         moreover
```
```   489         {assume mn: "m \<noteq> n" hence mn': "m < n" using m np by auto
```
```   490           from nn' m np have max1: "m \<le> max n n"  by simp
```
```   491           hence min1: "m \<le> min n n" by simp
```
```   492           hence min2: "m \<le> min n (Suc n)" by simp
```
```   493           from "4.hyps"(16-18)[OF norm(1,4) min1]
```
```   494             "4.hyps"(13-15)[OF norm(1,2) min2]
```
```   495             degreen_polyadd[OF norm(3,6) max1]
```
```   496
```
```   497           have "degreen (?cnp *\<^sub>p c' +\<^sub>p CN 0\<^sub>p n (?cnp *\<^sub>p p')) m
```
```   498             \<le> max (degreen (?cnp *\<^sub>p c') m) (degreen (CN 0\<^sub>p n (?cnp *\<^sub>p p')) m)"
```
```   499             using mn nn' np np' by simp
```
```   500           with "4.hyps"(16-18)[OF norm(1,4) min1]
```
```   501             "4.hyps"(13-15)[OF norm(1,2) min2]
```
```   502             degreen_0[OF norm(3) mn']
```
```   503           have ?eq using nn' mn np np' by clarsimp}
```
```   504         ultimately have ?eq by blast}
```
```   505       ultimately show ?eq by blast}
```
```   506     { case (2 n0 n1)
```
```   507       hence np: "isnpolyh ?cnp n0" and np': "isnpolyh ?cnp' n1"
```
```   508         and m: "m \<le> min n0 n1" by simp_all
```
```   509       hence mn: "m \<le> n" by simp
```
```   510       let ?c0p = "CN 0\<^sub>p n (?cnp *\<^sub>p p')"
```
```   511       {assume C: "?cnp *\<^sub>p c' +\<^sub>p ?c0p = 0\<^sub>p" "n' = n"
```
```   512         hence nn: "\<not>n' < n \<and> \<not> n<n'" by simp
```
```   513         from "4.hyps"(16-18) [of n n n]
```
```   514           "4.hyps"(13-15)[of n "Suc n" n]
```
```   515           np np' C(2) mn
```
```   516         have norm: "isnpolyh ?cnp n" "isnpolyh c' (Suc n)" "isnpolyh (?cnp *\<^sub>p c') n"
```
```   517           "isnpolyh p' n" "isnpolyh (?cnp *\<^sub>p p') n" "isnpolyh (CN 0\<^sub>p n (CN c n p *\<^sub>p p')) n"
```
```   518           "(?cnp *\<^sub>p c' = 0\<^sub>p) = (c' = 0\<^sub>p)"
```
```   519           "?cnp *\<^sub>p p' \<noteq> 0\<^sub>p"
```
```   520           "degreen (?cnp *\<^sub>p c') n = (if c'=0\<^sub>p then 0 else degreen ?cnp n + degreen c' n)"
```
```   521             "degreen (?cnp *\<^sub>p p') n = degreen ?cnp n + degreen p' n"
```
```   522           by (simp_all add: min_def)
```
```   523
```
```   524           from norm have cn: "isnpolyh (CN 0\<^sub>p n (CN c n p *\<^sub>p p')) n" by simp
```
```   525           have degneq: "degreen (?cnp *\<^sub>p c') n < degreen (CN 0\<^sub>p n (?cnp *\<^sub>p p')) n"
```
```   526             using norm by simp
```
```   527         from polyadd_eq_const_degreen[OF norm(3) cn C(1), where m="n"]  degneq
```
```   528         have "False" by simp }
```
```   529       thus ?case using "4.hyps" by clarsimp}
```
```   530 qed auto
```
```   531
```
```   532 lemma polymul[simp]: "Ipoly bs (p *\<^sub>p q) = (Ipoly bs p) * (Ipoly bs q)"
```
```   533 by(induct p q rule: polymul.induct, auto simp add: field_simps)
```
```   534
```
```   535 lemma polymul_normh:
```
```   536     assumes "SORT_CONSTRAINT('a::{field_char_0, field_inverse_zero})"
```
```   537   shows "\<lbrakk>isnpolyh p n0 ; isnpolyh q n1\<rbrakk> \<Longrightarrow> isnpolyh (p *\<^sub>p q) (min n0 n1)"
```
```   538   using polymul_properties(1)  by blast
```
```   539 lemma polymul_eq0_iff:
```
```   540   assumes "SORT_CONSTRAINT('a::{field_char_0, field_inverse_zero})"
```
```   541   shows "\<lbrakk> isnpolyh p n0 ; isnpolyh q n1\<rbrakk> \<Longrightarrow> (p *\<^sub>p q = 0\<^sub>p) = (p = 0\<^sub>p \<or> q = 0\<^sub>p) "
```
```   542   using polymul_properties(2)  by blast
```
```   543 lemma polymul_degreen:
```
```   544   assumes "SORT_CONSTRAINT('a::{field_char_0, field_inverse_zero})"
```
```   545   shows "\<lbrakk> isnpolyh p n0 ; isnpolyh q n1 ; m \<le> min n0 n1\<rbrakk> \<Longrightarrow> degreen (p *\<^sub>p q) m = (if (p = 0\<^sub>p \<or> q = 0\<^sub>p) then 0 else degreen p m + degreen q m)"
```
```   546   using polymul_properties(3) by blast
```
```   547 lemma polymul_norm:
```
```   548   assumes "SORT_CONSTRAINT('a::{field_char_0, field_inverse_zero})"
```
```   549   shows "\<lbrakk> isnpoly p; isnpoly q\<rbrakk> \<Longrightarrow> isnpoly (polymul p q)"
```
```   550   using polymul_normh[of "p" "0" "q" "0"] isnpoly_def by simp
```
```   551
```
```   552 lemma headconst_zero: "isnpolyh p n0 \<Longrightarrow> headconst p = 0\<^sub>N \<longleftrightarrow> p = 0\<^sub>p"
```
```   553   by (induct p arbitrary: n0 rule: headconst.induct, auto)
```
```   554
```
```   555 lemma headconst_isnormNum: "isnpolyh p n0 \<Longrightarrow> isnormNum (headconst p)"
```
```   556   by (induct p arbitrary: n0, auto)
```
```   557
```
```   558 lemma monic_eqI: assumes np: "isnpolyh p n0"
```
```   559   shows "INum (headconst p) * Ipoly bs (fst (monic p)) = (Ipoly bs p ::'a::{field_char_0, field_inverse_zero, power})"
```
```   560   unfolding monic_def Let_def
```
```   561 proof(cases "headconst p = 0\<^sub>N", simp_all add: headconst_zero[OF np])
```
```   562   let ?h = "headconst p"
```
```   563   assume pz: "p \<noteq> 0\<^sub>p"
```
```   564   {assume hz: "INum ?h = (0::'a)"
```
```   565     from headconst_isnormNum[OF np] have norm: "isnormNum ?h" "isnormNum 0\<^sub>N" by simp_all
```
```   566     from isnormNum_unique[where ?'a = 'a, OF norm] hz have "?h = 0\<^sub>N" by simp
```
```   567     with headconst_zero[OF np] have "p =0\<^sub>p" by blast with pz have "False" by blast}
```
```   568   thus "INum (headconst p) = (0::'a) \<longrightarrow> \<lparr>p\<rparr>\<^sub>p\<^bsup>bs\<^esup> = 0" by blast
```
```   569 qed
```
```   570
```
```   571
```
```   572 text{* polyneg is a negation and preserves normal forms *}
```
```   573
```
```   574 lemma polyneg[simp]: "Ipoly bs (polyneg p) = - Ipoly bs p"
```
```   575 by (induct p rule: polyneg.induct, auto)
```
```   576
```
```   577 lemma polyneg0: "isnpolyh p n \<Longrightarrow> ((~\<^sub>p p) = 0\<^sub>p) = (p = 0\<^sub>p)"
```
```   578   by (induct p arbitrary: n rule: polyneg.induct, auto simp add: Nneg_def)
```
```   579 lemma polyneg_polyneg: "isnpolyh p n0 \<Longrightarrow> ~\<^sub>p (~\<^sub>p p) = p"
```
```   580   by (induct p arbitrary: n0 rule: polyneg.induct, auto)
```
```   581 lemma polyneg_normh: "\<And>n. isnpolyh p n \<Longrightarrow> isnpolyh (polyneg p) n "
```
```   582 by (induct p rule: polyneg.induct, auto simp add: polyneg0)
```
```   583
```
```   584 lemma polyneg_norm: "isnpoly p \<Longrightarrow> isnpoly (polyneg p)"
```
```   585   using isnpoly_def polyneg_normh by simp
```
```   586
```
```   587
```
```   588 text{* polysub is a substraction and preserves normal forms *}
```
```   589
```
```   590 lemma polysub[simp]: "Ipoly bs (polysub p q) = (Ipoly bs p) - (Ipoly bs q)"
```
```   591 by (simp add: polysub_def polyneg polyadd)
```
```   592 lemma polysub_normh: "\<And> n0 n1. \<lbrakk> isnpolyh p n0 ; isnpolyh q n1\<rbrakk> \<Longrightarrow> isnpolyh (polysub p q) (min n0 n1)"
```
```   593 by (simp add: polysub_def polyneg_normh polyadd_normh)
```
```   594
```
```   595 lemma polysub_norm: "\<lbrakk> isnpoly p; isnpoly q\<rbrakk> \<Longrightarrow> isnpoly (polysub p q)"
```
```   596   using polyadd_norm polyneg_norm by (simp add: polysub_def)
```
```   597 lemma polysub_same_0[simp]:   assumes "SORT_CONSTRAINT('a::{field_char_0, field_inverse_zero})"
```
```   598   shows "isnpolyh p n0 \<Longrightarrow> polysub p p = 0\<^sub>p"
```
```   599 unfolding polysub_def split_def fst_conv snd_conv
```
```   600 by (induct p arbitrary: n0,auto simp add: Let_def Nsub0[simplified Nsub_def])
```
```   601
```
```   602 lemma polysub_0:
```
```   603   assumes "SORT_CONSTRAINT('a::{field_char_0, field_inverse_zero})"
```
```   604   shows "\<lbrakk> isnpolyh p n0 ; isnpolyh q n1\<rbrakk> \<Longrightarrow> (p -\<^sub>p q = 0\<^sub>p) = (p = q)"
```
```   605   unfolding polysub_def split_def fst_conv snd_conv
```
```   606   by (induct p q arbitrary: n0 n1 rule:polyadd.induct)
```
```   607   (auto simp: Nsub0[simplified Nsub_def] Let_def)
```
```   608
```
```   609 text{* polypow is a power function and preserves normal forms *}
```
```   610
```
```   611 lemma polypow[simp]: "Ipoly bs (polypow n p) = ((Ipoly bs p :: 'a::{field_char_0, field_inverse_zero})) ^ n"
```
```   612 proof(induct n rule: polypow.induct)
```
```   613   case 1 thus ?case by simp
```
```   614 next
```
```   615   case (2 n)
```
```   616   let ?q = "polypow ((Suc n) div 2) p"
```
```   617   let ?d = "polymul ?q ?q"
```
```   618   have "odd (Suc n) \<or> even (Suc n)" by simp
```
```   619   moreover
```
```   620   {assume odd: "odd (Suc n)"
```
```   621     have th: "(Suc (Suc (Suc (0\<Colon>nat)) * (Suc n div Suc (Suc (0\<Colon>nat))))) = Suc n div 2 + Suc n div 2 + 1" by arith
```
```   622     from odd have "Ipoly bs (p ^\<^sub>p Suc n) = Ipoly bs (polymul p ?d)" by (simp add: Let_def)
```
```   623     also have "\<dots> = (Ipoly bs p) * (Ipoly bs p)^(Suc n div 2)*(Ipoly bs p)^(Suc n div 2)"
```
```   624       using "2.hyps" by simp
```
```   625     also have "\<dots> = (Ipoly bs p) ^ (Suc n div 2 + Suc n div 2 + 1)"
```
```   626       apply (simp only: power_add power_one_right) by simp
```
```   627     also have "\<dots> = (Ipoly bs p) ^ (Suc (Suc (Suc (0\<Colon>nat)) * (Suc n div Suc (Suc (0\<Colon>nat)))))"
```
```   628       by (simp only: th)
```
```   629     finally have ?case
```
```   630     using odd_nat_div_two_times_two_plus_one[OF odd, symmetric] by simp  }
```
```   631   moreover
```
```   632   {assume even: "even (Suc n)"
```
```   633     have th: "(Suc (Suc (0\<Colon>nat))) * (Suc n div Suc (Suc (0\<Colon>nat))) = Suc n div 2 + Suc n div 2" by arith
```
```   634     from even have "Ipoly bs (p ^\<^sub>p Suc n) = Ipoly bs ?d" by (simp add: Let_def)
```
```   635     also have "\<dots> = (Ipoly bs p) ^ (Suc n div 2 + Suc n div 2)"
```
```   636       using "2.hyps" apply (simp only: power_add) by simp
```
```   637     finally have ?case using even_nat_div_two_times_two[OF even] by (simp only: th)}
```
```   638   ultimately show ?case by blast
```
```   639 qed
```
```   640
```
```   641 lemma polypow_normh:
```
```   642     assumes "SORT_CONSTRAINT('a::{field_char_0, field_inverse_zero})"
```
```   643   shows "isnpolyh p n \<Longrightarrow> isnpolyh (polypow k p) n"
```
```   644 proof (induct k arbitrary: n rule: polypow.induct)
```
```   645   case (2 k n)
```
```   646   let ?q = "polypow (Suc k div 2) p"
```
```   647   let ?d = "polymul ?q ?q"
```
```   648   from prems have th1:"isnpolyh ?q n" and th2: "isnpolyh p n" by blast+
```
```   649   from polymul_normh[OF th1 th1] have dn: "isnpolyh ?d n" by simp
```
```   650   from polymul_normh[OF th2 dn] have on: "isnpolyh (polymul p ?d) n" by simp
```
```   651   from dn on show ?case by (simp add: Let_def)
```
```   652 qed auto
```
```   653
```
```   654 lemma polypow_norm:
```
```   655   assumes "SORT_CONSTRAINT('a::{field_char_0, field_inverse_zero})"
```
```   656   shows "isnpoly p \<Longrightarrow> isnpoly (polypow k p)"
```
```   657   by (simp add: polypow_normh isnpoly_def)
```
```   658
```
```   659 text{* Finally the whole normalization *}
```
```   660
```
```   661 lemma polynate[simp]: "Ipoly bs (polynate p) = (Ipoly bs p :: 'a ::{field_char_0, field_inverse_zero})"
```
```   662 by (induct p rule:polynate.induct, auto)
```
```   663
```
```   664 lemma polynate_norm[simp]:
```
```   665   assumes "SORT_CONSTRAINT('a::{field_char_0, field_inverse_zero})"
```
```   666   shows "isnpoly (polynate p)"
```
```   667   by (induct p rule: polynate.induct, simp_all add: polyadd_norm polymul_norm polysub_norm polyneg_norm polypow_norm) (simp_all add: isnpoly_def)
```
```   668
```
```   669 text{* shift1 *}
```
```   670
```
```   671
```
```   672 lemma shift1: "Ipoly bs (shift1 p) = Ipoly bs (Mul (Bound 0) p)"
```
```   673 by (simp add: shift1_def polymul)
```
```   674
```
```   675 lemma shift1_isnpoly:
```
```   676   assumes pn: "isnpoly p" and pnz: "p \<noteq> 0\<^sub>p" shows "isnpoly (shift1 p) "
```
```   677   using pn pnz by (simp add: shift1_def isnpoly_def )
```
```   678
```
```   679 lemma shift1_nz[simp]:"shift1 p \<noteq> 0\<^sub>p"
```
```   680   by (simp add: shift1_def)
```
```   681 lemma funpow_shift1_isnpoly:
```
```   682   "\<lbrakk> isnpoly p ; p \<noteq> 0\<^sub>p\<rbrakk> \<Longrightarrow> isnpoly (funpow n shift1 p)"
```
```   683   by (induct n arbitrary: p) (auto simp add: shift1_isnpoly funpow_swap1)
```
```   684
```
```   685 lemma funpow_isnpolyh:
```
```   686   assumes f: "\<And> p. isnpolyh p n \<Longrightarrow> isnpolyh (f p) n "and np: "isnpolyh p n"
```
```   687   shows "isnpolyh (funpow k f p) n"
```
```   688   using f np by (induct k arbitrary: p, auto)
```
```   689
```
```   690 lemma funpow_shift1: "(Ipoly bs (funpow n shift1 p) :: 'a :: {field_char_0, field_inverse_zero}) = Ipoly bs (Mul (Pw (Bound 0) n) p)"
```
```   691   by (induct n arbitrary: p, simp_all add: shift1_isnpoly shift1 power_Suc )
```
```   692
```
```   693 lemma shift1_isnpolyh: "isnpolyh p n0 \<Longrightarrow> p\<noteq> 0\<^sub>p \<Longrightarrow> isnpolyh (shift1 p) 0"
```
```   694   using isnpolyh_mono[where n="n0" and n'="0" and p="p"] by (simp add: shift1_def)
```
```   695
```
```   696 lemma funpow_shift1_1:
```
```   697   "(Ipoly bs (funpow n shift1 p) :: 'a :: {field_char_0, field_inverse_zero}) = Ipoly bs (funpow n shift1 1\<^sub>p *\<^sub>p p)"
```
```   698   by (simp add: funpow_shift1)
```
```   699
```
```   700 lemma poly_cmul[simp]: "Ipoly bs (poly_cmul c p) = Ipoly bs (Mul (C c) p)"
```
```   701 by (induct p  arbitrary: n0 rule: poly_cmul.induct, auto simp add: field_simps)
```
```   702
```
```   703 lemma behead:
```
```   704   assumes np: "isnpolyh p n"
```
```   705   shows "Ipoly bs (Add (Mul (head p) (Pw (Bound 0) (degree p))) (behead p)) = (Ipoly bs p :: 'a :: {field_char_0, field_inverse_zero})"
```
```   706   using np
```
```   707 proof (induct p arbitrary: n rule: behead.induct)
```
```   708   case (1 c p n) hence pn: "isnpolyh p n" by simp
```
```   709   from prems(2)[OF pn]
```
```   710   have th:"Ipoly bs (Add (Mul (head p) (Pw (Bound 0) (degree p))) (behead p)) = Ipoly bs p" .
```
```   711   then show ?case using "1.hyps" apply (simp add: Let_def,cases "behead p = 0\<^sub>p")
```
```   712     by (simp_all add: th[symmetric] field_simps power_Suc)
```
```   713 qed (auto simp add: Let_def)
```
```   714
```
```   715 lemma behead_isnpolyh:
```
```   716   assumes np: "isnpolyh p n" shows "isnpolyh (behead p) n"
```
```   717   using np by (induct p rule: behead.induct, auto simp add: Let_def isnpolyh_mono)
```
```   718
```
```   719 subsection{* Miscellaneous lemmas about indexes, decrementation, substitution  etc ... *}
```
```   720 lemma isnpolyh_polybound0: "isnpolyh p (Suc n) \<Longrightarrow> polybound0 p"
```
```   721 proof(induct p arbitrary: n rule: poly.induct, auto)
```
```   722   case (goal1 c n p n')
```
```   723   hence "n = Suc (n - 1)" by simp
```
```   724   hence "isnpolyh p (Suc (n - 1))"  using `isnpolyh p n` by simp
```
```   725   with prems(2) show ?case by simp
```
```   726 qed
```
```   727
```
```   728 lemma isconstant_polybound0: "isnpolyh p n0 \<Longrightarrow> isconstant p \<longleftrightarrow> polybound0 p"
```
```   729 by (induct p arbitrary: n0 rule: isconstant.induct, auto simp add: isnpolyh_polybound0)
```
```   730
```
```   731 lemma decrpoly_zero[simp]: "decrpoly p = 0\<^sub>p \<longleftrightarrow> p = 0\<^sub>p" by (induct p, auto)
```
```   732
```
```   733 lemma decrpoly_normh: "isnpolyh p n0 \<Longrightarrow> polybound0 p \<Longrightarrow> isnpolyh (decrpoly p) (n0 - 1)"
```
```   734   apply (induct p arbitrary: n0, auto)
```
```   735   apply (atomize)
```
```   736   apply (erule_tac x = "Suc nat" in allE)
```
```   737   apply auto
```
```   738   done
```
```   739
```
```   740 lemma head_polybound0: "isnpolyh p n0 \<Longrightarrow> polybound0 (head p)"
```
```   741  by (induct p  arbitrary: n0 rule: head.induct, auto intro: isnpolyh_polybound0)
```
```   742
```
```   743 lemma polybound0_I:
```
```   744   assumes nb: "polybound0 a"
```
```   745   shows "Ipoly (b#bs) a = Ipoly (b'#bs) a"
```
```   746 using nb
```
```   747 by (induct a rule: poly.induct) auto
```
```   748 lemma polysubst0_I:
```
```   749   shows "Ipoly (b#bs) (polysubst0 a t) = Ipoly ((Ipoly (b#bs) a)#bs) t"
```
```   750   by (induct t) simp_all
```
```   751
```
```   752 lemma polysubst0_I':
```
```   753   assumes nb: "polybound0 a"
```
```   754   shows "Ipoly (b#bs) (polysubst0 a t) = Ipoly ((Ipoly (b'#bs) a)#bs) t"
```
```   755   by (induct t) (simp_all add: polybound0_I[OF nb, where b="b" and b'="b'"])
```
```   756
```
```   757 lemma decrpoly: assumes nb: "polybound0 t"
```
```   758   shows "Ipoly (x#bs) t = Ipoly bs (decrpoly t)"
```
```   759   using nb by (induct t rule: decrpoly.induct, simp_all)
```
```   760
```
```   761 lemma polysubst0_polybound0: assumes nb: "polybound0 t"
```
```   762   shows "polybound0 (polysubst0 t a)"
```
```   763 using nb by (induct a rule: poly.induct, auto)
```
```   764
```
```   765 lemma degree0_polybound0: "isnpolyh p n \<Longrightarrow> degree p = 0 \<Longrightarrow> polybound0 p"
```
```   766   by (induct p arbitrary: n rule: degree.induct, auto simp add: isnpolyh_polybound0)
```
```   767
```
```   768 primrec maxindex :: "poly \<Rightarrow> nat" where
```
```   769   "maxindex (Bound n) = n + 1"
```
```   770 | "maxindex (CN c n p) = max  (n + 1) (max (maxindex c) (maxindex p))"
```
```   771 | "maxindex (Add p q) = max (maxindex p) (maxindex q)"
```
```   772 | "maxindex (Sub p q) = max (maxindex p) (maxindex q)"
```
```   773 | "maxindex (Mul p q) = max (maxindex p) (maxindex q)"
```
```   774 | "maxindex (Neg p) = maxindex p"
```
```   775 | "maxindex (Pw p n) = maxindex p"
```
```   776 | "maxindex (C x) = 0"
```
```   777
```
```   778 definition wf_bs :: "'a list \<Rightarrow> poly \<Rightarrow> bool" where
```
```   779   "wf_bs bs p = (length bs \<ge> maxindex p)"
```
```   780
```
```   781 lemma wf_bs_coefficients: "wf_bs bs p \<Longrightarrow> \<forall> c \<in> set (coefficients p). wf_bs bs c"
```
```   782 proof(induct p rule: coefficients.induct)
```
```   783   case (1 c p)
```
```   784   show ?case
```
```   785   proof
```
```   786     fix x assume xc: "x \<in> set (coefficients (CN c 0 p))"
```
```   787     hence "x = c \<or> x \<in> set (coefficients p)" by simp
```
```   788     moreover
```
```   789     {assume "x = c" hence "wf_bs bs x" using "1.prems"  unfolding wf_bs_def by simp}
```
```   790     moreover
```
```   791     {assume H: "x \<in> set (coefficients p)"
```
```   792       from "1.prems" have "wf_bs bs p" unfolding wf_bs_def by simp
```
```   793       with "1.hyps" H have "wf_bs bs x" by blast }
```
```   794     ultimately  show "wf_bs bs x" by blast
```
```   795   qed
```
```   796 qed simp_all
```
```   797
```
```   798 lemma maxindex_coefficients: " \<forall>c\<in> set (coefficients p). maxindex c \<le> maxindex p"
```
```   799 by (induct p rule: coefficients.induct, auto)
```
```   800
```
```   801 lemma wf_bs_I: "wf_bs bs p ==> Ipoly (bs@bs') p = Ipoly bs p"
```
```   802   unfolding wf_bs_def by (induct p, auto simp add: nth_append)
```
```   803
```
```   804 lemma take_maxindex_wf: assumes wf: "wf_bs bs p"
```
```   805   shows "Ipoly (take (maxindex p) bs) p = Ipoly bs p"
```
```   806 proof-
```
```   807   let ?ip = "maxindex p"
```
```   808   let ?tbs = "take ?ip bs"
```
```   809   from wf have "length ?tbs = ?ip" unfolding wf_bs_def by simp
```
```   810   hence wf': "wf_bs ?tbs p" unfolding wf_bs_def by  simp
```
```   811   have eq: "bs = ?tbs @ (drop ?ip bs)" by simp
```
```   812   from wf_bs_I[OF wf', of "drop ?ip bs"] show ?thesis using eq by simp
```
```   813 qed
```
```   814
```
```   815 lemma decr_maxindex: "polybound0 p \<Longrightarrow> maxindex (decrpoly p) = maxindex p - 1"
```
```   816   by (induct p, auto)
```
```   817
```
```   818 lemma wf_bs_insensitive: "length bs = length bs' \<Longrightarrow> wf_bs bs p = wf_bs bs' p"
```
```   819   unfolding wf_bs_def by simp
```
```   820
```
```   821 lemma wf_bs_insensitive': "wf_bs (x#bs) p = wf_bs (y#bs) p"
```
```   822   unfolding wf_bs_def by simp
```
```   823
```
```   824
```
```   825
```
```   826 lemma wf_bs_coefficients': "\<forall>c \<in> set (coefficients p). wf_bs bs c \<Longrightarrow> wf_bs (x#bs) p"
```
```   827 by(induct p rule: coefficients.induct, auto simp add: wf_bs_def)
```
```   828 lemma coefficients_Nil[simp]: "coefficients p \<noteq> []"
```
```   829   by (induct p rule: coefficients.induct, simp_all)
```
```   830
```
```   831
```
```   832 lemma coefficients_head: "last (coefficients p) = head p"
```
```   833   by (induct p rule: coefficients.induct, auto)
```
```   834
```
```   835 lemma wf_bs_decrpoly: "wf_bs bs (decrpoly p) \<Longrightarrow> wf_bs (x#bs) p"
```
```   836   unfolding wf_bs_def by (induct p rule: decrpoly.induct, auto)
```
```   837
```
```   838 lemma length_le_list_ex: "length xs \<le> n \<Longrightarrow> \<exists> ys. length (xs @ ys) = n"
```
```   839   apply (rule exI[where x="replicate (n - length xs) z"])
```
```   840   by simp
```
```   841 lemma isnpolyh_Suc_const:"isnpolyh p (Suc n) \<Longrightarrow> isconstant p"
```
```   842 by (cases p, auto) (case_tac "nat", simp_all)
```
```   843
```
```   844 lemma wf_bs_polyadd: "wf_bs bs p \<and> wf_bs bs q \<longrightarrow> wf_bs bs (p +\<^sub>p q)"
```
```   845   unfolding wf_bs_def
```
```   846   apply (induct p q rule: polyadd.induct)
```
```   847   apply (auto simp add: Let_def)
```
```   848   done
```
```   849
```
```   850 lemma wf_bs_polyul: "wf_bs bs p \<Longrightarrow> wf_bs bs q \<Longrightarrow> wf_bs bs (p *\<^sub>p q)"
```
```   851   unfolding wf_bs_def
```
```   852   apply (induct p q arbitrary: bs rule: polymul.induct)
```
```   853   apply (simp_all add: wf_bs_polyadd)
```
```   854   apply clarsimp
```
```   855   apply (rule wf_bs_polyadd[unfolded wf_bs_def, rule_format])
```
```   856   apply auto
```
```   857   done
```
```   858
```
```   859 lemma wf_bs_polyneg: "wf_bs bs p \<Longrightarrow> wf_bs bs (~\<^sub>p p)"
```
```   860   unfolding wf_bs_def by (induct p rule: polyneg.induct, auto)
```
```   861
```
```   862 lemma wf_bs_polysub: "wf_bs bs p \<Longrightarrow> wf_bs bs q \<Longrightarrow> wf_bs bs (p -\<^sub>p q)"
```
```   863   unfolding polysub_def split_def fst_conv snd_conv using wf_bs_polyadd wf_bs_polyneg by blast
```
```   864
```
```   865 subsection{* Canonicity of polynomial representation, see lemma isnpolyh_unique*}
```
```   866
```
```   867 definition "polypoly bs p = map (Ipoly bs) (coefficients p)"
```
```   868 definition "polypoly' bs p = map ((Ipoly bs o decrpoly)) (coefficients p)"
```
```   869 definition "poly_nate bs p = map ((Ipoly bs o decrpoly)) (coefficients (polynate p))"
```
```   870
```
```   871 lemma coefficients_normh: "isnpolyh p n0 \<Longrightarrow> \<forall> q \<in> set (coefficients p). isnpolyh q n0"
```
```   872 proof (induct p arbitrary: n0 rule: coefficients.induct)
```
```   873   case (1 c p n0)
```
```   874   have cp: "isnpolyh (CN c 0 p) n0" by fact
```
```   875   hence norm: "isnpolyh c 0" "isnpolyh p 0" "p \<noteq> 0\<^sub>p" "n0 = 0"
```
```   876     by (auto simp add: isnpolyh_mono[where n'=0])
```
```   877   from "1.hyps"[OF norm(2)] norm(1) norm(4)  show ?case by simp
```
```   878 qed auto
```
```   879
```
```   880 lemma coefficients_isconst:
```
```   881   "isnpolyh p n \<Longrightarrow> \<forall>q\<in>set (coefficients p). isconstant q"
```
```   882   by (induct p arbitrary: n rule: coefficients.induct,
```
```   883     auto simp add: isnpolyh_Suc_const)
```
```   884
```
```   885 lemma polypoly_polypoly':
```
```   886   assumes np: "isnpolyh p n0"
```
```   887   shows "polypoly (x#bs) p = polypoly' bs p"
```
```   888 proof-
```
```   889   let ?cf = "set (coefficients p)"
```
```   890   from coefficients_normh[OF np] have cn_norm: "\<forall> q\<in> ?cf. isnpolyh q n0" .
```
```   891   {fix q assume q: "q \<in> ?cf"
```
```   892     from q cn_norm have th: "isnpolyh q n0" by blast
```
```   893     from coefficients_isconst[OF np] q have "isconstant q" by blast
```
```   894     with isconstant_polybound0[OF th] have "polybound0 q" by blast}
```
```   895   hence "\<forall>q \<in> ?cf. polybound0 q" ..
```
```   896   hence "\<forall>q \<in> ?cf. Ipoly (x#bs) q = Ipoly bs (decrpoly q)"
```
```   897     using polybound0_I[where b=x and bs=bs and b'=y] decrpoly[where x=x and bs=bs]
```
```   898     by auto
```
```   899
```
```   900   thus ?thesis unfolding polypoly_def polypoly'_def by simp
```
```   901 qed
```
```   902
```
```   903 lemma polypoly_poly:
```
```   904   assumes np: "isnpolyh p n0" shows "Ipoly (x#bs) p = poly (polypoly (x#bs) p) x"
```
```   905   using np
```
```   906 by (induct p arbitrary: n0 bs rule: coefficients.induct, auto simp add: polypoly_def)
```
```   907
```
```   908 lemma polypoly'_poly:
```
```   909   assumes np: "isnpolyh p n0" shows "\<lparr>p\<rparr>\<^sub>p\<^bsup>x # bs\<^esup> = poly (polypoly' bs p) x"
```
```   910   using polypoly_poly[OF np, simplified polypoly_polypoly'[OF np]] .
```
```   911
```
```   912
```
```   913 lemma polypoly_poly_polybound0:
```
```   914   assumes np: "isnpolyh p n0" and nb: "polybound0 p"
```
```   915   shows "polypoly bs p = [Ipoly bs p]"
```
```   916   using np nb unfolding polypoly_def
```
```   917   by (cases p, auto, case_tac nat, auto)
```
```   918
```
```   919 lemma head_isnpolyh: "isnpolyh p n0 \<Longrightarrow> isnpolyh (head p) n0"
```
```   920   by (induct p rule: head.induct, auto)
```
```   921
```
```   922 lemma headn_nz[simp]: "isnpolyh p n0 \<Longrightarrow> (headn p m = 0\<^sub>p) = (p = 0\<^sub>p)"
```
```   923   by (cases p,auto)
```
```   924
```
```   925 lemma head_eq_headn0: "head p = headn p 0"
```
```   926   by (induct p rule: head.induct, simp_all)
```
```   927
```
```   928 lemma head_nz[simp]: "isnpolyh p n0 \<Longrightarrow> (head p = 0\<^sub>p) = (p = 0\<^sub>p)"
```
```   929   by (simp add: head_eq_headn0)
```
```   930
```
```   931 lemma isnpolyh_zero_iff:
```
```   932   assumes nq: "isnpolyh p n0" and eq :"\<forall>bs. wf_bs bs p \<longrightarrow> \<lparr>p\<rparr>\<^sub>p\<^bsup>bs\<^esup> = (0::'a::{field_char_0, field_inverse_zero, power})"
```
```   933   shows "p = 0\<^sub>p"
```
```   934 using nq eq
```
```   935 proof (induct "maxindex p" arbitrary: p n0 rule: less_induct)
```
```   936   case less
```
```   937   note np = `isnpolyh p n0` and zp = `\<forall>bs. wf_bs bs p \<longrightarrow> \<lparr>p\<rparr>\<^sub>p\<^bsup>bs\<^esup> = (0::'a)`
```
```   938   {assume nz: "maxindex p = 0"
```
```   939     then obtain c where "p = C c" using np by (cases p, auto)
```
```   940     with zp np have "p = 0\<^sub>p" unfolding wf_bs_def by simp}
```
```   941   moreover
```
```   942   {assume nz: "maxindex p \<noteq> 0"
```
```   943     let ?h = "head p"
```
```   944     let ?hd = "decrpoly ?h"
```
```   945     let ?ihd = "maxindex ?hd"
```
```   946     from head_isnpolyh[OF np] head_polybound0[OF np] have h:"isnpolyh ?h n0" "polybound0 ?h"
```
```   947       by simp_all
```
```   948     hence nhd: "isnpolyh ?hd (n0 - 1)" using decrpoly_normh by blast
```
```   949
```
```   950     from maxindex_coefficients[of p] coefficients_head[of p, symmetric]
```
```   951     have mihn: "maxindex ?h \<le> maxindex p" by auto
```
```   952     with decr_maxindex[OF h(2)] nz  have ihd_lt_n: "?ihd < maxindex p" by auto
```
```   953     {fix bs:: "'a list"  assume bs: "wf_bs bs ?hd"
```
```   954       let ?ts = "take ?ihd bs"
```
```   955       let ?rs = "drop ?ihd bs"
```
```   956       have ts: "wf_bs ?ts ?hd" using bs unfolding wf_bs_def by simp
```
```   957       have bs_ts_eq: "?ts@ ?rs = bs" by simp
```
```   958       from wf_bs_decrpoly[OF ts] have tsh: " \<forall>x. wf_bs (x#?ts) ?h" by simp
```
```   959       from ihd_lt_n have "ALL x. length (x#?ts) \<le> maxindex p" by simp
```
```   960       with length_le_list_ex obtain xs where xs:"length ((x#?ts) @ xs) = maxindex p" by blast
```
```   961       hence "\<forall> x. wf_bs ((x#?ts) @ xs) p" unfolding wf_bs_def by simp
```
```   962       with zp have "\<forall> x. Ipoly ((x#?ts) @ xs) p = 0" by blast
```
```   963       hence "\<forall> x. Ipoly (x#(?ts @ xs)) p = 0" by simp
```
```   964       with polypoly_poly[OF np, where ?'a = 'a] polypoly_polypoly'[OF np, where ?'a = 'a]
```
```   965       have "\<forall>x. poly (polypoly' (?ts @ xs) p) x = poly [] x"  by simp
```
```   966       hence "poly (polypoly' (?ts @ xs) p) = poly []" by (auto intro: ext)
```
```   967       hence "\<forall> c \<in> set (coefficients p). Ipoly (?ts @ xs) (decrpoly c) = 0"
```
```   968         using poly_zero[where ?'a='a] by (simp add: polypoly'_def list_all_iff)
```
```   969       with coefficients_head[of p, symmetric]
```
```   970       have th0: "Ipoly (?ts @ xs) ?hd = 0" by simp
```
```   971       from bs have wf'': "wf_bs ?ts ?hd" unfolding wf_bs_def by simp
```
```   972       with th0 wf_bs_I[of ?ts ?hd xs] have "Ipoly ?ts ?hd = 0" by simp
```
```   973       with wf'' wf_bs_I[of ?ts ?hd ?rs] bs_ts_eq have "\<lparr>?hd\<rparr>\<^sub>p\<^bsup>bs\<^esup> = 0" by simp }
```
```   974     then have hdz: "\<forall>bs. wf_bs bs ?hd \<longrightarrow> \<lparr>?hd\<rparr>\<^sub>p\<^bsup>bs\<^esup> = (0::'a)" by blast
```
```   975
```
```   976     from less(1)[OF ihd_lt_n nhd] hdz have "?hd = 0\<^sub>p" by blast
```
```   977     hence "?h = 0\<^sub>p" by simp
```
```   978     with head_nz[OF np] have "p = 0\<^sub>p" by simp}
```
```   979   ultimately show "p = 0\<^sub>p" by blast
```
```   980 qed
```
```   981
```
```   982 lemma isnpolyh_unique:
```
```   983   assumes np:"isnpolyh p n0" and nq: "isnpolyh q n1"
```
```   984   shows "(\<forall>bs. \<lparr>p\<rparr>\<^sub>p\<^bsup>bs\<^esup> = (\<lparr>q\<rparr>\<^sub>p\<^bsup>bs\<^esup> :: 'a::{field_char_0, field_inverse_zero, power})) \<longleftrightarrow>  p = q"
```
```   985 proof(auto)
```
```   986   assume H: "\<forall>bs. (\<lparr>p\<rparr>\<^sub>p\<^bsup>bs\<^esup> ::'a)= \<lparr>q\<rparr>\<^sub>p\<^bsup>bs\<^esup>"
```
```   987   hence "\<forall>bs.\<lparr>p -\<^sub>p q\<rparr>\<^sub>p\<^bsup>bs\<^esup>= (0::'a)" by simp
```
```   988   hence "\<forall>bs. wf_bs bs (p -\<^sub>p q) \<longrightarrow> \<lparr>p -\<^sub>p q\<rparr>\<^sub>p\<^bsup>bs\<^esup> = (0::'a)"
```
```   989     using wf_bs_polysub[where p=p and q=q] by auto
```
```   990   with isnpolyh_zero_iff[OF polysub_normh[OF np nq]] polysub_0[OF np nq]
```
```   991   show "p = q" by blast
```
```   992 qed
```
```   993
```
```   994
```
```   995 text{* consequences of unicity on the algorithms for polynomial normalization *}
```
```   996
```
```   997 lemma polyadd_commute:   assumes "SORT_CONSTRAINT('a::{field_char_0, field_inverse_zero})"
```
```   998   and np: "isnpolyh p n0" and nq: "isnpolyh q n1" shows "p +\<^sub>p q = q +\<^sub>p p"
```
```   999   using isnpolyh_unique[OF polyadd_normh[OF np nq] polyadd_normh[OF nq np]] by simp
```
```  1000
```
```  1001 lemma zero_normh: "isnpolyh 0\<^sub>p n" by simp
```
```  1002 lemma one_normh: "isnpolyh 1\<^sub>p n" by simp
```
```  1003 lemma polyadd_0[simp]:
```
```  1004   assumes "SORT_CONSTRAINT('a::{field_char_0, field_inverse_zero})"
```
```  1005   and np: "isnpolyh p n0" shows "p +\<^sub>p 0\<^sub>p = p" and "0\<^sub>p +\<^sub>p p = p"
```
```  1006   using isnpolyh_unique[OF polyadd_normh[OF np zero_normh] np]
```
```  1007     isnpolyh_unique[OF polyadd_normh[OF zero_normh np] np] by simp_all
```
```  1008
```
```  1009 lemma polymul_1[simp]:
```
```  1010     assumes "SORT_CONSTRAINT('a::{field_char_0, field_inverse_zero})"
```
```  1011   and np: "isnpolyh p n0" shows "p *\<^sub>p 1\<^sub>p = p" and "1\<^sub>p *\<^sub>p p = p"
```
```  1012   using isnpolyh_unique[OF polymul_normh[OF np one_normh] np]
```
```  1013     isnpolyh_unique[OF polymul_normh[OF one_normh np] np] by simp_all
```
```  1014 lemma polymul_0[simp]:
```
```  1015   assumes "SORT_CONSTRAINT('a::{field_char_0, field_inverse_zero})"
```
```  1016   and np: "isnpolyh p n0" shows "p *\<^sub>p 0\<^sub>p = 0\<^sub>p" and "0\<^sub>p *\<^sub>p p = 0\<^sub>p"
```
```  1017   using isnpolyh_unique[OF polymul_normh[OF np zero_normh] zero_normh]
```
```  1018     isnpolyh_unique[OF polymul_normh[OF zero_normh np] zero_normh] by simp_all
```
```  1019
```
```  1020 lemma polymul_commute:
```
```  1021     assumes "SORT_CONSTRAINT('a::{field_char_0, field_inverse_zero})"
```
```  1022   and np:"isnpolyh p n0" and nq: "isnpolyh q n1"
```
```  1023   shows "p *\<^sub>p q = q *\<^sub>p p"
```
```  1024 using isnpolyh_unique[OF polymul_normh[OF np nq] polymul_normh[OF nq np], where ?'a = "'a\<Colon>{field_char_0, field_inverse_zero, power}"] by simp
```
```  1025
```
```  1026 declare polyneg_polyneg[simp]
```
```  1027
```
```  1028 lemma isnpolyh_polynate_id[simp]:
```
```  1029   assumes "SORT_CONSTRAINT('a::{field_char_0, field_inverse_zero})"
```
```  1030   and np:"isnpolyh p n0" shows "polynate p = p"
```
```  1031   using isnpolyh_unique[where ?'a= "'a::{field_char_0, field_inverse_zero}", OF polynate_norm[of p, unfolded isnpoly_def] np] polynate[where ?'a = "'a::{field_char_0, field_inverse_zero}"] by simp
```
```  1032
```
```  1033 lemma polynate_idempotent[simp]:
```
```  1034     assumes "SORT_CONSTRAINT('a::{field_char_0, field_inverse_zero})"
```
```  1035   shows "polynate (polynate p) = polynate p"
```
```  1036   using isnpolyh_polynate_id[OF polynate_norm[of p, unfolded isnpoly_def]] .
```
```  1037
```
```  1038 lemma poly_nate_polypoly': "poly_nate bs p = polypoly' bs (polynate p)"
```
```  1039   unfolding poly_nate_def polypoly'_def ..
```
```  1040 lemma poly_nate_poly: shows "poly (poly_nate bs p) = (\<lambda>x:: 'a ::{field_char_0, field_inverse_zero}. \<lparr>p\<rparr>\<^sub>p\<^bsup>x # bs\<^esup>)"
```
```  1041   using polypoly'_poly[OF polynate_norm[unfolded isnpoly_def], symmetric, of bs p]
```
```  1042   unfolding poly_nate_polypoly' by (auto intro: ext)
```
```  1043
```
```  1044 subsection{* heads, degrees and all that *}
```
```  1045 lemma degree_eq_degreen0: "degree p = degreen p 0"
```
```  1046   by (induct p rule: degree.induct, simp_all)
```
```  1047
```
```  1048 lemma degree_polyneg: assumes n: "isnpolyh p n"
```
```  1049   shows "degree (polyneg p) = degree p"
```
```  1050   using n
```
```  1051   by (induct p arbitrary: n rule: polyneg.induct, simp_all) (case_tac na, auto)
```
```  1052
```
```  1053 lemma degree_polyadd:
```
```  1054   assumes np: "isnpolyh p n0" and nq: "isnpolyh q n1"
```
```  1055   shows "degree (p +\<^sub>p q) \<le> max (degree p) (degree q)"
```
```  1056 using degreen_polyadd[OF np nq, where m= "0"] degree_eq_degreen0 by simp
```
```  1057
```
```  1058
```
```  1059 lemma degree_polysub: assumes np: "isnpolyh p n0" and nq: "isnpolyh q n1"
```
```  1060   shows "degree (p -\<^sub>p q) \<le> max (degree p) (degree q)"
```
```  1061 proof-
```
```  1062   from nq have nq': "isnpolyh (~\<^sub>p q) n1" using polyneg_normh by simp
```
```  1063   from degree_polyadd[OF np nq'] show ?thesis by (simp add: polysub_def degree_polyneg[OF nq])
```
```  1064 qed
```
```  1065
```
```  1066 lemma degree_polysub_samehead:
```
```  1067   assumes "SORT_CONSTRAINT('a::{field_char_0, field_inverse_zero})"
```
```  1068   and np: "isnpolyh p n0" and nq: "isnpolyh q n1" and h: "head p = head q"
```
```  1069   and d: "degree p = degree q"
```
```  1070   shows "degree (p -\<^sub>p q) < degree p \<or> (p -\<^sub>p q = 0\<^sub>p)"
```
```  1071 unfolding polysub_def split_def fst_conv snd_conv
```
```  1072 using np nq h d
```
```  1073 proof(induct p q rule:polyadd.induct)
```
```  1074   case (1 c c') thus ?case by (simp add: Nsub_def Nsub0[simplified Nsub_def])
```
```  1075 next
```
```  1076   case (2 c c' n' p')
```
```  1077   from prems have "degree (C c) = degree (CN c' n' p')" by simp
```
```  1078   hence nz:"n' > 0" by (cases n', auto)
```
```  1079   hence "head (CN c' n' p') = CN c' n' p'" by (cases n', auto)
```
```  1080   with prems show ?case by simp
```
```  1081 next
```
```  1082   case (3 c n p c')
```
```  1083   from prems have "degree (C c') = degree (CN c n p)" by simp
```
```  1084   hence nz:"n > 0" by (cases n, auto)
```
```  1085   hence "head (CN c n p) = CN c n p" by (cases n, auto)
```
```  1086   with prems show ?case by simp
```
```  1087 next
```
```  1088   case (4 c n p c' n' p')
```
```  1089   hence H: "isnpolyh (CN c n p) n0" "isnpolyh (CN c' n' p') n1"
```
```  1090     "head (CN c n p) = head (CN c' n' p')" "degree (CN c n p) = degree (CN c' n' p')" by simp+
```
```  1091   hence degc: "degree c = 0" and degc': "degree c' = 0" by simp_all
```
```  1092   hence degnc: "degree (~\<^sub>p c) = 0" and degnc': "degree (~\<^sub>p c') = 0"
```
```  1093     using H(1-2) degree_polyneg by auto
```
```  1094   from H have cnh: "isnpolyh c (Suc n)" and c'nh: "isnpolyh c' (Suc n')"  by simp+
```
```  1095   from degree_polysub[OF cnh c'nh, simplified polysub_def] degc degc' have degcmc': "degree (c +\<^sub>p  ~\<^sub>pc') = 0"  by simp
```
```  1096   from H have pnh: "isnpolyh p n" and p'nh: "isnpolyh p' n'" by auto
```
```  1097   have "n = n' \<or> n < n' \<or> n > n'" by arith
```
```  1098   moreover
```
```  1099   {assume nn': "n = n'"
```
```  1100     have "n = 0 \<or> n >0" by arith
```
```  1101     moreover {assume nz: "n = 0" hence ?case using prems by (auto simp add: Let_def degcmc')}
```
```  1102     moreover {assume nz: "n > 0"
```
```  1103       with nn' H(3) have  cc':"c = c'" and pp': "p = p'" by (cases n, auto)+
```
```  1104       hence ?case using polysub_same_0[OF p'nh, simplified polysub_def split_def fst_conv snd_conv] polysub_same_0[OF c'nh, simplified polysub_def split_def fst_conv snd_conv] using nn' prems by (simp add: Let_def)}
```
```  1105     ultimately have ?case by blast}
```
```  1106   moreover
```
```  1107   {assume nn': "n < n'" hence n'p: "n' > 0" by simp
```
```  1108     hence headcnp':"head (CN c' n' p') = CN c' n' p'"  by (cases n', simp_all)
```
```  1109     have degcnp': "degree (CN c' n' p') = 0" and degcnpeq: "degree (CN c n p) = degree (CN c' n' p')" using prems by (cases n', simp_all)
```
```  1110     hence "n > 0" by (cases n, simp_all)
```
```  1111     hence headcnp: "head (CN c n p) = CN c n p" by (cases n, auto)
```
```  1112     from H(3) headcnp headcnp' nn' have ?case by auto}
```
```  1113   moreover
```
```  1114   {assume nn': "n > n'"  hence np: "n > 0" by simp
```
```  1115     hence headcnp:"head (CN c n p) = CN c n p"  by (cases n, simp_all)
```
```  1116     from prems have degcnpeq: "degree (CN c' n' p') = degree (CN c n p)" by simp
```
```  1117     from np have degcnp: "degree (CN c n p) = 0" by (cases n, simp_all)
```
```  1118     with degcnpeq have "n' > 0" by (cases n', simp_all)
```
```  1119     hence headcnp': "head (CN c' n' p') = CN c' n' p'" by (cases n', auto)
```
```  1120     from H(3) headcnp headcnp' nn' have ?case by auto}
```
```  1121   ultimately show ?case  by blast
```
```  1122 qed auto
```
```  1123
```
```  1124 lemma shift1_head : "isnpolyh p n0 \<Longrightarrow> head (shift1 p) = head p"
```
```  1125 by (induct p arbitrary: n0 rule: head.induct, simp_all add: shift1_def)
```
```  1126
```
```  1127 lemma funpow_shift1_head: "isnpolyh p n0 \<Longrightarrow> p\<noteq> 0\<^sub>p \<Longrightarrow> head (funpow k shift1 p) = head p"
```
```  1128 proof(induct k arbitrary: n0 p)
```
```  1129   case (Suc k n0 p) hence "isnpolyh (shift1 p) 0" by (simp add: shift1_isnpolyh)
```
```  1130   with prems have "head (funpow k shift1 (shift1 p)) = head (shift1 p)"
```
```  1131     and "head (shift1 p) = head p" by (simp_all add: shift1_head)
```
```  1132   thus ?case by (simp add: funpow_swap1)
```
```  1133 qed auto
```
```  1134
```
```  1135 lemma shift1_degree: "degree (shift1 p) = 1 + degree p"
```
```  1136   by (simp add: shift1_def)
```
```  1137 lemma funpow_shift1_degree: "degree (funpow k shift1 p) = k + degree p "
```
```  1138   by (induct k arbitrary: p, auto simp add: shift1_degree)
```
```  1139
```
```  1140 lemma funpow_shift1_nz: "p \<noteq> 0\<^sub>p \<Longrightarrow> funpow n shift1 p \<noteq> 0\<^sub>p"
```
```  1141   by (induct n arbitrary: p, simp_all add: funpow_def)
```
```  1142
```
```  1143 lemma head_isnpolyh_Suc[simp]: "isnpolyh p (Suc n) \<Longrightarrow> head p = p"
```
```  1144   by (induct p arbitrary: n rule: degree.induct, auto)
```
```  1145 lemma headn_0[simp]: "isnpolyh p n \<Longrightarrow> m < n \<Longrightarrow> headn p m = p"
```
```  1146   by (induct p arbitrary: n rule: degreen.induct, auto)
```
```  1147 lemma head_isnpolyh_Suc': "n > 0 \<Longrightarrow> isnpolyh p n \<Longrightarrow> head p = p"
```
```  1148   by (induct p arbitrary: n rule: degree.induct, auto)
```
```  1149 lemma head_head[simp]: "isnpolyh p n0 \<Longrightarrow> head (head p) = head p"
```
```  1150   by (induct p rule: head.induct, auto)
```
```  1151
```
```  1152 lemma polyadd_eq_const_degree:
```
```  1153   "\<lbrakk> isnpolyh p n0 ; isnpolyh q n1 ; polyadd p q = C c\<rbrakk> \<Longrightarrow> degree p = degree q"
```
```  1154   using polyadd_eq_const_degreen degree_eq_degreen0 by simp
```
```  1155
```
```  1156 lemma polyadd_head: assumes np: "isnpolyh p n0" and nq: "isnpolyh q n1"
```
```  1157   and deg: "degree p \<noteq> degree q"
```
```  1158   shows "head (p +\<^sub>p q) = (if degree p < degree q then head q else head p)"
```
```  1159 using np nq deg
```
```  1160 apply(induct p q arbitrary: n0 n1 rule: polyadd.induct,simp_all)
```
```  1161 apply (case_tac n', simp, simp)
```
```  1162 apply (case_tac n, simp, simp)
```
```  1163 apply (case_tac n, case_tac n', simp add: Let_def)
```
```  1164 apply (case_tac "pa +\<^sub>p p' = 0\<^sub>p")
```
```  1165 apply (auto simp add: polyadd_eq_const_degree)
```
```  1166 apply (metis head_nz)
```
```  1167 apply (metis head_nz)
```
```  1168 apply (metis degree.simps(9) gr0_conv_Suc head.simps(1) less_Suc0 not_less_eq)
```
```  1169 by (metis degree.simps(9) gr0_conv_Suc nat_less_le order_le_less_trans)
```
```  1170
```
```  1171 lemma polymul_head_polyeq:
```
```  1172    assumes "SORT_CONSTRAINT('a::{field_char_0, field_inverse_zero})"
```
```  1173   shows "\<lbrakk>isnpolyh p n0; isnpolyh q n1 ; p \<noteq> 0\<^sub>p ; q \<noteq> 0\<^sub>p \<rbrakk> \<Longrightarrow> head (p *\<^sub>p q) = head p *\<^sub>p head q"
```
```  1174 proof (induct p q arbitrary: n0 n1 rule: polymul.induct)
```
```  1175   case (2 c c' n' p' n0 n1)
```
```  1176   hence "isnpolyh (head (CN c' n' p')) n1" "isnormNum c"  by (simp_all add: head_isnpolyh)
```
```  1177   thus ?case using prems by (cases n', auto)
```
```  1178 next
```
```  1179   case (3 c n p c' n0 n1)
```
```  1180   hence "isnpolyh (head (CN c n p)) n0" "isnormNum c'"  by (simp_all add: head_isnpolyh)
```
```  1181   thus ?case using prems by (cases n, auto)
```
```  1182 next
```
```  1183   case (4 c n p c' n' p' n0 n1)
```
```  1184   hence norm: "isnpolyh p n" "isnpolyh c (Suc n)" "isnpolyh p' n'" "isnpolyh c' (Suc n')"
```
```  1185     "isnpolyh (CN c n p) n" "isnpolyh (CN c' n' p') n'"
```
```  1186     by simp_all
```
```  1187   have "n < n' \<or> n' < n \<or> n = n'" by arith
```
```  1188   moreover
```
```  1189   {assume nn': "n < n'" hence ?case
```
```  1190       using norm
```
```  1191     "4.hyps"(2)[OF norm(1,6)]
```
```  1192     "4.hyps"(1)[OF norm(2,6)] by (simp, cases n, simp,cases n', simp_all)}
```
```  1193   moreover {assume nn': "n'< n"
```
```  1194     hence ?case using norm "4.hyps"(6) [OF norm(5,3)]
```
```  1195       "4.hyps"(5)[OF norm(5,4)]
```
```  1196       by (simp,cases n',simp,cases n,auto)}
```
```  1197   moreover {assume nn': "n' = n"
```
```  1198     from nn' polymul_normh[OF norm(5,4)]
```
```  1199     have ncnpc':"isnpolyh (CN c n p *\<^sub>p c') n" by (simp add: min_def)
```
```  1200     from nn' polymul_normh[OF norm(5,3)] norm
```
```  1201     have ncnpp':"isnpolyh (CN c n p *\<^sub>p p') n" by simp
```
```  1202     from nn' ncnpp' polymul_eq0_iff[OF norm(5,3)] norm(6)
```
```  1203     have ncnpp0':"isnpolyh (CN 0\<^sub>p n (CN c n p *\<^sub>p p')) n" by simp
```
```  1204     from polyadd_normh[OF ncnpc' ncnpp0']
```
```  1205     have nth: "isnpolyh ((CN c n p *\<^sub>p c') +\<^sub>p (CN 0\<^sub>p n (CN c n p *\<^sub>p p'))) n"
```
```  1206       by (simp add: min_def)
```
```  1207     {assume np: "n > 0"
```
```  1208       with nn' head_isnpolyh_Suc'[OF np nth]
```
```  1209         head_isnpolyh_Suc'[OF np norm(5)] head_isnpolyh_Suc'[OF np norm(6)[simplified nn']]
```
```  1210       have ?case by simp}
```
```  1211     moreover
```
```  1212     {moreover assume nz: "n = 0"
```
```  1213       from polymul_degreen[OF norm(5,4), where m="0"]
```
```  1214         polymul_degreen[OF norm(5,3), where m="0"] nn' nz degree_eq_degreen0
```
```  1215       norm(5,6) degree_npolyhCN[OF norm(6)]
```
```  1216     have dth:"degree (CN c 0 p *\<^sub>p c') < degree (CN 0\<^sub>p 0 (CN c 0 p *\<^sub>p p'))" by simp
```
```  1217     hence dth':"degree (CN c 0 p *\<^sub>p c') \<noteq> degree (CN 0\<^sub>p 0 (CN c 0 p *\<^sub>p p'))" by simp
```
```  1218     from polyadd_head[OF ncnpc'[simplified nz] ncnpp0'[simplified nz] dth'] dth
```
```  1219     have ?case   using norm "4.hyps"(6)[OF norm(5,3)]
```
```  1220         "4.hyps"(5)[OF norm(5,4)] nn' nz by simp }
```
```  1221     ultimately have ?case by (cases n) auto}
```
```  1222   ultimately show ?case by blast
```
```  1223 qed simp_all
```
```  1224
```
```  1225 lemma degree_coefficients: "degree p = length (coefficients p) - 1"
```
```  1226   by(induct p rule: degree.induct, auto)
```
```  1227
```
```  1228 lemma degree_head[simp]: "degree (head p) = 0"
```
```  1229   by (induct p rule: head.induct, auto)
```
```  1230
```
```  1231 lemma degree_CN: "isnpolyh p n \<Longrightarrow> degree (CN c n p) \<le> 1 + degree p"
```
```  1232   by (cases n, simp_all)
```
```  1233 lemma degree_CN': "isnpolyh p n \<Longrightarrow> degree (CN c n p) \<ge>  degree p"
```
```  1234   by (cases n, simp_all)
```
```  1235
```
```  1236 lemma polyadd_different_degree: "\<lbrakk>isnpolyh p n0 ; isnpolyh q n1; degree p \<noteq> degree q\<rbrakk> \<Longrightarrow> degree (polyadd p q) = max (degree p) (degree q)"
```
```  1237   using polyadd_different_degreen degree_eq_degreen0 by simp
```
```  1238
```
```  1239 lemma degreen_polyneg: "isnpolyh p n0 \<Longrightarrow> degreen (~\<^sub>p p) m = degreen p m"
```
```  1240   by (induct p arbitrary: n0 rule: polyneg.induct, auto)
```
```  1241
```
```  1242 lemma degree_polymul:
```
```  1243   assumes "SORT_CONSTRAINT('a::{field_char_0, field_inverse_zero})"
```
```  1244   and np: "isnpolyh p n0" and nq: "isnpolyh q n1"
```
```  1245   shows "degree (p *\<^sub>p q) \<le> degree p + degree q"
```
```  1246   using polymul_degreen[OF np nq, where m="0"]  degree_eq_degreen0 by simp
```
```  1247
```
```  1248 lemma polyneg_degree: "isnpolyh p n \<Longrightarrow> degree (polyneg p) = degree p"
```
```  1249   by (induct p arbitrary: n rule: degree.induct, auto)
```
```  1250
```
```  1251 lemma polyneg_head: "isnpolyh p n \<Longrightarrow> head(polyneg p) = polyneg (head p)"
```
```  1252   by (induct p arbitrary: n rule: degree.induct, auto)
```
```  1253
```
```  1254 subsection {* Correctness of polynomial pseudo division *}
```
```  1255
```
```  1256 lemma polydivide_aux_properties:
```
```  1257   assumes "SORT_CONSTRAINT('a::{field_char_0, field_inverse_zero})"
```
```  1258   and np: "isnpolyh p n0" and ns: "isnpolyh s n1"
```
```  1259   and ap: "head p = a" and ndp: "degree p = n" and pnz: "p \<noteq> 0\<^sub>p"
```
```  1260   shows "(polydivide_aux a n p k s = (k',r) \<longrightarrow> (k' \<ge> k) \<and> (degree r = 0 \<or> degree r < degree p)
```
```  1261           \<and> (\<exists>nr. isnpolyh r nr) \<and> (\<exists>q n1. isnpolyh q n1 \<and> ((polypow (k' - k) a) *\<^sub>p s = p *\<^sub>p q +\<^sub>p r)))"
```
```  1262   using ns
```
```  1263 proof(induct "degree s" arbitrary: s k k' r n1 rule: less_induct)
```
```  1264   case less
```
```  1265   let ?qths = "\<exists>q n1. isnpolyh q n1 \<and> (a ^\<^sub>p (k' - k) *\<^sub>p s = p *\<^sub>p q +\<^sub>p r)"
```
```  1266   let ?ths = "polydivide_aux a n p k s = (k', r) \<longrightarrow>  k \<le> k' \<and> (degree r = 0 \<or> degree r < degree p)
```
```  1267     \<and> (\<exists>nr. isnpolyh r nr) \<and> ?qths"
```
```  1268   let ?b = "head s"
```
```  1269   let ?p' = "funpow (degree s - n) shift1 p"
```
```  1270   let ?xdn = "funpow (degree s - n) shift1 1\<^sub>p"
```
```  1271   let ?akk' = "a ^\<^sub>p (k' - k)"
```
```  1272   note ns = `isnpolyh s n1`
```
```  1273   from np have np0: "isnpolyh p 0"
```
```  1274     using isnpolyh_mono[where n="n0" and n'="0" and p="p"]  by simp
```
```  1275   have np': "isnpolyh ?p' 0" using funpow_shift1_isnpoly[OF np0[simplified isnpoly_def[symmetric]] pnz, where n="degree s - n"] isnpoly_def by simp
```
```  1276   have headp': "head ?p' = head p" using funpow_shift1_head[OF np pnz] by simp
```
```  1277   from funpow_shift1_isnpoly[where p="1\<^sub>p"] have nxdn: "isnpolyh ?xdn 0" by (simp add: isnpoly_def)
```
```  1278   from polypow_normh [OF head_isnpolyh[OF np0], where k="k' - k"] ap
```
```  1279   have nakk':"isnpolyh ?akk' 0" by blast
```
```  1280   {assume sz: "s = 0\<^sub>p"
```
```  1281    hence ?ths using np polydivide_aux.simps apply clarsimp by (rule exI[where x="0\<^sub>p"], simp) }
```
```  1282   moreover
```
```  1283   {assume sz: "s \<noteq> 0\<^sub>p"
```
```  1284     {assume dn: "degree s < n"
```
```  1285       hence "?ths" using ns ndp np polydivide_aux.simps by auto (rule exI[where x="0\<^sub>p"],simp) }
```
```  1286     moreover
```
```  1287     {assume dn': "\<not> degree s < n" hence dn: "degree s \<ge> n" by arith
```
```  1288       have degsp': "degree s = degree ?p'"
```
```  1289         using dn ndp funpow_shift1_degree[where k = "degree s - n" and p="p"] by simp
```
```  1290       {assume ba: "?b = a"
```
```  1291         hence headsp': "head s = head ?p'" using ap headp' by simp
```
```  1292         have nr: "isnpolyh (s -\<^sub>p ?p') 0" using polysub_normh[OF ns np'] by simp
```
```  1293         from degree_polysub_samehead[OF ns np' headsp' degsp']
```
```  1294         have "degree (s -\<^sub>p ?p') < degree s \<or> s -\<^sub>p ?p' = 0\<^sub>p" by simp
```
```  1295         moreover
```
```  1296         {assume deglt:"degree (s -\<^sub>p ?p') < degree s"
```
```  1297           from polydivide_aux.simps sz dn' ba
```
```  1298           have eq: "polydivide_aux a n p k s = polydivide_aux a n p k (s -\<^sub>p ?p')"
```
```  1299             by (simp add: Let_def)
```
```  1300           {assume h1: "polydivide_aux a n p k s = (k', r)"
```
```  1301             from less(1)[OF deglt nr, of k k' r]
```
```  1302               trans[OF eq[symmetric] h1]
```
```  1303             have kk': "k \<le> k'" and nr:"\<exists>nr. isnpolyh r nr" and dr: "degree r = 0 \<or> degree r < degree p"
```
```  1304               and q1:"\<exists>q nq. isnpolyh q nq \<and> (a ^\<^sub>p k' - k *\<^sub>p (s -\<^sub>p ?p') = p *\<^sub>p q +\<^sub>p r)" by auto
```
```  1305             from q1 obtain q n1 where nq: "isnpolyh q n1"
```
```  1306               and asp:"a^\<^sub>p (k' - k) *\<^sub>p (s -\<^sub>p ?p') = p *\<^sub>p q +\<^sub>p r"  by blast
```
```  1307             from nr obtain nr where nr': "isnpolyh r nr" by blast
```
```  1308             from polymul_normh[OF nakk' ns] have nakks': "isnpolyh (a ^\<^sub>p (k' - k) *\<^sub>p s) 0" by simp
```
```  1309             from polyadd_normh[OF polymul_normh[OF nakk' nxdn] nq]
```
```  1310             have nq': "isnpolyh (?akk' *\<^sub>p ?xdn +\<^sub>p q) 0" by simp
```
```  1311             from polyadd_normh[OF polymul_normh[OF np
```
```  1312               polyadd_normh[OF polymul_normh[OF nakk' nxdn] nq]] nr']
```
```  1313             have nqr': "isnpolyh (p *\<^sub>p (?akk' *\<^sub>p ?xdn +\<^sub>p q) +\<^sub>p r) 0" by simp
```
```  1314             from asp have "\<forall> (bs:: 'a::{field_char_0, field_inverse_zero} list). Ipoly bs (a^\<^sub>p (k' - k) *\<^sub>p (s -\<^sub>p ?p')) =
```
```  1315               Ipoly bs (p *\<^sub>p q +\<^sub>p r)" by simp
```
```  1316             hence " \<forall>(bs:: 'a::{field_char_0, field_inverse_zero} list). Ipoly bs (a^\<^sub>p (k' - k)*\<^sub>p s) =
```
```  1317               Ipoly bs (a^\<^sub>p (k' - k)) * Ipoly bs ?p' + Ipoly bs p * Ipoly bs q + Ipoly bs r"
```
```  1318               by (simp add: field_simps)
```
```  1319             hence " \<forall>(bs:: 'a::{field_char_0, field_inverse_zero} list). Ipoly bs (a ^\<^sub>p (k' - k) *\<^sub>p s) =
```
```  1320               Ipoly bs (a^\<^sub>p (k' - k)) * Ipoly bs (funpow (degree s - n) shift1 1\<^sub>p *\<^sub>p p)
```
```  1321               + Ipoly bs p * Ipoly bs q + Ipoly bs r"
```
```  1322               by (auto simp only: funpow_shift1_1)
```
```  1323             hence "\<forall>(bs:: 'a::{field_char_0, field_inverse_zero} list). Ipoly bs (a ^\<^sub>p (k' - k) *\<^sub>p s) =
```
```  1324               Ipoly bs p * (Ipoly bs (a^\<^sub>p (k' - k)) * Ipoly bs (funpow (degree s - n) shift1 1\<^sub>p)
```
```  1325               + Ipoly bs q) + Ipoly bs r" by (simp add: field_simps)
```
```  1326             hence "\<forall>(bs:: 'a::{field_char_0, field_inverse_zero} list). Ipoly bs (a ^\<^sub>p (k' - k) *\<^sub>p s) =
```
```  1327               Ipoly bs (p *\<^sub>p ((a^\<^sub>p (k' - k)) *\<^sub>p (funpow (degree s - n) shift1 1\<^sub>p) +\<^sub>p q) +\<^sub>p r)" by simp
```
```  1328             with isnpolyh_unique[OF nakks' nqr']
```
```  1329             have "a ^\<^sub>p (k' - k) *\<^sub>p s =
```
```  1330               p *\<^sub>p ((a^\<^sub>p (k' - k)) *\<^sub>p (funpow (degree s - n) shift1 1\<^sub>p) +\<^sub>p q) +\<^sub>p r" by blast
```
```  1331             hence ?qths using nq'
```
```  1332               apply (rule_tac x="(a^\<^sub>p (k' - k)) *\<^sub>p (funpow (degree s - n) shift1 1\<^sub>p) +\<^sub>p q" in exI)
```
```  1333               apply (rule_tac x="0" in exI) by simp
```
```  1334             with kk' nr dr have "k \<le> k' \<and> (degree r = 0 \<or> degree r < degree p) \<and> (\<exists>nr. isnpolyh r nr) \<and> ?qths"
```
```  1335               by blast } hence ?ths by blast }
```
```  1336         moreover
```
```  1337         {assume spz:"s -\<^sub>p ?p' = 0\<^sub>p"
```
```  1338           from spz isnpolyh_unique[OF polysub_normh[OF ns np'], where q="0\<^sub>p", symmetric, where ?'a = "'a::{field_char_0, field_inverse_zero}"]
```
```  1339           have " \<forall>(bs:: 'a::{field_char_0, field_inverse_zero} list). Ipoly bs s = Ipoly bs ?p'" by simp
```
```  1340           hence "\<forall>(bs:: 'a::{field_char_0, field_inverse_zero} list). Ipoly bs s = Ipoly bs (?xdn *\<^sub>p p)" using np nxdn apply simp
```
```  1341             by (simp only: funpow_shift1_1) simp
```
```  1342           hence sp': "s = ?xdn *\<^sub>p p" using isnpolyh_unique[OF ns polymul_normh[OF nxdn np]] by blast
```
```  1343           {assume h1: "polydivide_aux a n p k s = (k',r)"
```
```  1344             from polydivide_aux.simps sz dn' ba
```
```  1345             have eq: "polydivide_aux a n p k s = polydivide_aux a n p k (s -\<^sub>p ?p')"
```
```  1346               by (simp add: Let_def)
```
```  1347             also have "\<dots> = (k,0\<^sub>p)" using polydivide_aux.simps spz by simp
```
```  1348             finally have "(k',r) = (k,0\<^sub>p)" using h1 by simp
```
```  1349             with sp'[symmetric] ns np nxdn polyadd_0(1)[OF polymul_normh[OF np nxdn]]
```
```  1350               polyadd_0(2)[OF polymul_normh[OF np nxdn]] have ?ths
```
```  1351               apply auto
```
```  1352               apply (rule exI[where x="?xdn"])
```
```  1353               apply (auto simp add: polymul_commute[of p])
```
```  1354               done} }
```
```  1355         ultimately have ?ths by blast }
```
```  1356       moreover
```
```  1357       {assume ba: "?b \<noteq> a"
```
```  1358         from polysub_normh[OF polymul_normh[OF head_isnpolyh[OF np0, simplified ap] ns]
```
```  1359           polymul_normh[OF head_isnpolyh[OF ns] np']]
```
```  1360         have nth: "isnpolyh ((a *\<^sub>p s) -\<^sub>p (?b *\<^sub>p ?p')) 0" by(simp add: min_def)
```
```  1361         have nzths: "a *\<^sub>p s \<noteq> 0\<^sub>p" "?b *\<^sub>p ?p' \<noteq> 0\<^sub>p"
```
```  1362           using polymul_eq0_iff[OF head_isnpolyh[OF np0, simplified ap] ns]
```
```  1363             polymul_eq0_iff[OF head_isnpolyh[OF ns] np']head_nz[OF np0] ap pnz sz head_nz[OF ns]
```
```  1364             funpow_shift1_nz[OF pnz] by simp_all
```
```  1365         from polymul_head_polyeq[OF head_isnpolyh[OF np] ns] head_nz[OF np] sz ap head_head[OF np] pnz
```
```  1366           polymul_head_polyeq[OF head_isnpolyh[OF ns] np'] head_nz [OF ns] sz funpow_shift1_nz[OF pnz, where n="degree s - n"]
```
```  1367         have hdth: "head (a *\<^sub>p s) = head (?b *\<^sub>p ?p')"
```
```  1368           using head_head[OF ns] funpow_shift1_head[OF np pnz]
```
```  1369             polymul_commute[OF head_isnpolyh[OF np] head_isnpolyh[OF ns]]
```
```  1370           by (simp add: ap)
```
```  1371         from polymul_degreen[OF head_isnpolyh[OF np] ns, where m="0"]
```
```  1372           head_nz[OF np] pnz sz ap[symmetric]
```
```  1373           funpow_shift1_nz[OF pnz, where n="degree s - n"]
```
```  1374           polymul_degreen[OF head_isnpolyh[OF ns] np', where m="0"]  head_nz[OF ns]
```
```  1375           ndp dn
```
```  1376         have degth: "degree (a *\<^sub>p s) = degree (?b *\<^sub>p ?p') "
```
```  1377           by (simp add: degree_eq_degreen0[symmetric] funpow_shift1_degree)
```
```  1378         {assume dth: "degree ((a *\<^sub>p s) -\<^sub>p (?b *\<^sub>p ?p')) < degree s"
```
```  1379           from polysub_normh[OF polymul_normh[OF head_isnpolyh[OF np] ns] polymul_normh[OF head_isnpolyh[OF ns]np']]
```
```  1380           ap have nasbp': "isnpolyh ((a *\<^sub>p s) -\<^sub>p (?b *\<^sub>p ?p')) 0" by simp
```
```  1381           {assume h1:"polydivide_aux a n p k s = (k', r)"
```
```  1382             from h1 polydivide_aux.simps sz dn' ba
```
```  1383             have eq:"polydivide_aux a n p (Suc k) ((a *\<^sub>p s) -\<^sub>p (?b *\<^sub>p ?p')) = (k',r)"
```
```  1384               by (simp add: Let_def)
```
```  1385             with less(1)[OF dth nasbp', of "Suc k" k' r]
```
```  1386             obtain q nq nr where kk': "Suc k \<le> k'" and nr: "isnpolyh r nr" and nq: "isnpolyh q nq"
```
```  1387               and dr: "degree r = 0 \<or> degree r < degree p"
```
```  1388               and qr: "a ^\<^sub>p (k' - Suc k) *\<^sub>p ((a *\<^sub>p s) -\<^sub>p (?b *\<^sub>p ?p')) = p *\<^sub>p q +\<^sub>p r" by auto
```
```  1389             from kk' have kk'':"Suc (k' - Suc k) = k' - k" by arith
```
```  1390             {fix bs:: "'a::{field_char_0, field_inverse_zero} list"
```
```  1391
```
```  1392             from qr isnpolyh_unique[OF polypow_normh[OF head_isnpolyh[OF np], where k="k' - Suc k", simplified ap] nasbp', symmetric]
```
```  1393             have "Ipoly bs (a ^\<^sub>p (k' - Suc k) *\<^sub>p ((a *\<^sub>p s) -\<^sub>p (?b *\<^sub>p ?p'))) = Ipoly bs (p *\<^sub>p q +\<^sub>p r)" by simp
```
```  1394             hence "Ipoly bs a ^ (Suc (k' - Suc k)) * Ipoly bs s = Ipoly bs p * Ipoly bs q + Ipoly bs a ^ (k' - Suc k) * Ipoly bs ?b * Ipoly bs ?p' + Ipoly bs r"
```
```  1395               by (simp add: field_simps power_Suc)
```
```  1396             hence "Ipoly bs a ^ (k' - k)  * Ipoly bs s = Ipoly bs p * Ipoly bs q + Ipoly bs a ^ (k' - Suc k) * Ipoly bs ?b * Ipoly bs ?xdn * Ipoly bs p + Ipoly bs r"
```
```  1397               by (simp add:kk'' funpow_shift1_1[where n="degree s - n" and p="p"])
```
```  1398             hence "Ipoly bs (a ^\<^sub>p (k' - k) *\<^sub>p s) = Ipoly bs p * (Ipoly bs q + Ipoly bs a ^ (k' - Suc k) * Ipoly bs ?b * Ipoly bs ?xdn) + Ipoly bs r"
```
```  1399               by (simp add: field_simps)}
```
```  1400             hence ieq:"\<forall>(bs :: 'a::{field_char_0, field_inverse_zero} list). Ipoly bs (a ^\<^sub>p (k' - k) *\<^sub>p s) =
```
```  1401               Ipoly bs (p *\<^sub>p (q +\<^sub>p (a ^\<^sub>p (k' - Suc k) *\<^sub>p ?b *\<^sub>p ?xdn)) +\<^sub>p r)" by auto
```
```  1402             let ?q = "q +\<^sub>p (a ^\<^sub>p (k' - Suc k) *\<^sub>p ?b *\<^sub>p ?xdn)"
```
```  1403             from polyadd_normh[OF nq polymul_normh[OF polymul_normh[OF polypow_normh[OF head_isnpolyh[OF np], where k="k' - Suc k"] head_isnpolyh[OF ns], simplified ap ] nxdn]]
```
```  1404             have nqw: "isnpolyh ?q 0" by simp
```
```  1405             from ieq isnpolyh_unique[OF polymul_normh[OF polypow_normh[OF head_isnpolyh[OF np], where k="k' - k"] ns, simplified ap] polyadd_normh[OF polymul_normh[OF np nqw] nr]]
```
```  1406             have asth: "(a ^\<^sub>p (k' - k) *\<^sub>p s) = p *\<^sub>p (q +\<^sub>p (a ^\<^sub>p (k' - Suc k) *\<^sub>p ?b *\<^sub>p ?xdn)) +\<^sub>p r" by blast
```
```  1407             from dr kk' nr h1 asth nqw have ?ths apply simp
```
```  1408               apply (rule conjI)
```
```  1409               apply (rule exI[where x="nr"], simp)
```
```  1410               apply (rule exI[where x="(q +\<^sub>p (a ^\<^sub>p (k' - Suc k) *\<^sub>p ?b *\<^sub>p ?xdn))"], simp)
```
```  1411               apply (rule exI[where x="0"], simp)
```
```  1412               done}
```
```  1413           hence ?ths by blast }
```
```  1414         moreover
```
```  1415         {assume spz: "a *\<^sub>p s -\<^sub>p (?b *\<^sub>p ?p') = 0\<^sub>p"
```
```  1416           {fix bs :: "'a::{field_char_0, field_inverse_zero} list"
```
```  1417             from isnpolyh_unique[OF nth, where ?'a="'a" and q="0\<^sub>p",simplified,symmetric] spz
```
```  1418           have "Ipoly bs (a*\<^sub>p s) = Ipoly bs ?b * Ipoly bs ?p'" by simp
```
```  1419           hence "Ipoly bs (a*\<^sub>p s) = Ipoly bs (?b *\<^sub>p ?xdn) * Ipoly bs p"
```
```  1420             by (simp add: funpow_shift1_1[where n="degree s - n" and p="p"])
```
```  1421           hence "Ipoly bs (a*\<^sub>p s) = Ipoly bs (p *\<^sub>p (?b *\<^sub>p ?xdn))" by simp
```
```  1422         }
```
```  1423         hence hth: "\<forall> (bs:: 'a::{field_char_0, field_inverse_zero} list). Ipoly bs (a*\<^sub>p s) = Ipoly bs (p *\<^sub>p (?b *\<^sub>p ?xdn))" ..
```
```  1424           from hth
```
```  1425           have asq: "a *\<^sub>p s = p *\<^sub>p (?b *\<^sub>p ?xdn)"
```
```  1426             using isnpolyh_unique[where ?'a = "'a::{field_char_0, field_inverse_zero}", OF polymul_normh[OF head_isnpolyh[OF np] ns]
```
```  1427                     polymul_normh[OF np polymul_normh[OF head_isnpolyh[OF ns] nxdn]],
```
```  1428               simplified ap] by simp
```
```  1429           {assume h1: "polydivide_aux a n p k s = (k', r)"
```
```  1430           from h1 sz ba dn' spz polydivide_aux.simps polydivide_aux.simps
```
```  1431           have "(k',r) = (Suc k, 0\<^sub>p)" by (simp add: Let_def)
```
```  1432           with h1 np head_isnpolyh[OF np, simplified ap] ns polymul_normh[OF head_isnpolyh[OF ns] nxdn]
```
```  1433             polymul_normh[OF np polymul_normh[OF head_isnpolyh[OF ns] nxdn]] asq
```
```  1434           have ?ths apply (clarsimp simp add: Let_def)
```
```  1435             apply (rule exI[where x="?b *\<^sub>p ?xdn"]) apply simp
```
```  1436             apply (rule exI[where x="0"], simp)
```
```  1437             done}
```
```  1438         hence ?ths by blast}
```
```  1439         ultimately have ?ths using  degree_polysub_samehead[OF polymul_normh[OF head_isnpolyh[OF np0, simplified ap] ns] polymul_normh[OF head_isnpolyh[OF ns] np'] hdth degth] polymul_degreen[OF head_isnpolyh[OF np] ns, where m="0"]
```
```  1440           head_nz[OF np] pnz sz ap[symmetric]
```
```  1441           by (simp add: degree_eq_degreen0[symmetric]) blast }
```
```  1442       ultimately have ?ths by blast
```
```  1443     }
```
```  1444     ultimately have ?ths by blast}
```
```  1445   ultimately show ?ths by blast
```
```  1446 qed
```
```  1447
```
```  1448 lemma polydivide_properties:
```
```  1449   assumes "SORT_CONSTRAINT('a::{field_char_0, field_inverse_zero})"
```
```  1450   and np: "isnpolyh p n0" and ns: "isnpolyh s n1" and pnz: "p \<noteq> 0\<^sub>p"
```
```  1451   shows "(\<exists> k r. polydivide s p = (k,r) \<and> (\<exists>nr. isnpolyh r nr) \<and> (degree r = 0 \<or> degree r < degree p)
```
```  1452   \<and> (\<exists>q n1. isnpolyh q n1 \<and> ((polypow k (head p)) *\<^sub>p s = p *\<^sub>p q +\<^sub>p r)))"
```
```  1453 proof-
```
```  1454   have trv: "head p = head p" "degree p = degree p" by simp_all
```
```  1455   from polydivide_def[where s="s" and p="p"]
```
```  1456   have ex: "\<exists> k r. polydivide s p = (k,r)" by auto
```
```  1457   then obtain k r where kr: "polydivide s p = (k,r)" by blast
```
```  1458   from trans[OF meta_eq_to_obj_eq[OF polydivide_def[where s="s"and p="p"], symmetric] kr]
```
```  1459     polydivide_aux_properties[OF np ns trv pnz, where k="0" and k'="k" and r="r"]
```
```  1460   have "(degree r = 0 \<or> degree r < degree p) \<and>
```
```  1461    (\<exists>nr. isnpolyh r nr) \<and> (\<exists>q n1. isnpolyh q n1 \<and> head p ^\<^sub>p k - 0 *\<^sub>p s = p *\<^sub>p q +\<^sub>p r)" by blast
```
```  1462   with kr show ?thesis
```
```  1463     apply -
```
```  1464     apply (rule exI[where x="k"])
```
```  1465     apply (rule exI[where x="r"])
```
```  1466     apply simp
```
```  1467     done
```
```  1468 qed
```
```  1469
```
```  1470 subsection{* More about polypoly and pnormal etc *}
```
```  1471
```
```  1472 definition "isnonconstant p = (\<not> isconstant p)"
```
```  1473
```
```  1474 lemma isnonconstant_pnormal_iff: assumes nc: "isnonconstant p"
```
```  1475   shows "pnormal (polypoly bs p) \<longleftrightarrow> Ipoly bs (head p) \<noteq> 0"
```
```  1476 proof
```
```  1477   let ?p = "polypoly bs p"
```
```  1478   assume H: "pnormal ?p"
```
```  1479   have csz: "coefficients p \<noteq> []" using nc by (cases p, auto)
```
```  1480
```
```  1481   from coefficients_head[of p] last_map[OF csz, of "Ipoly bs"]
```
```  1482     pnormal_last_nonzero[OF H]
```
```  1483   show "Ipoly bs (head p) \<noteq> 0" by (simp add: polypoly_def)
```
```  1484 next
```
```  1485   assume h: "\<lparr>head p\<rparr>\<^sub>p\<^bsup>bs\<^esup> \<noteq> 0"
```
```  1486   let ?p = "polypoly bs p"
```
```  1487   have csz: "coefficients p \<noteq> []" using nc by (cases p, auto)
```
```  1488   hence pz: "?p \<noteq> []" by (simp add: polypoly_def)
```
```  1489   hence lg: "length ?p > 0" by simp
```
```  1490   from h coefficients_head[of p] last_map[OF csz, of "Ipoly bs"]
```
```  1491   have lz: "last ?p \<noteq> 0" by (simp add: polypoly_def)
```
```  1492   from pnormal_last_length[OF lg lz] show "pnormal ?p" .
```
```  1493 qed
```
```  1494
```
```  1495 lemma isnonconstant_coefficients_length: "isnonconstant p \<Longrightarrow> length (coefficients p) > 1"
```
```  1496   unfolding isnonconstant_def
```
```  1497   apply (cases p, simp_all)
```
```  1498   apply (case_tac nat, auto)
```
```  1499   done
```
```  1500 lemma isnonconstant_nonconstant: assumes inc: "isnonconstant p"
```
```  1501   shows "nonconstant (polypoly bs p) \<longleftrightarrow> Ipoly bs (head p) \<noteq> 0"
```
```  1502 proof
```
```  1503   let ?p = "polypoly bs p"
```
```  1504   assume nc: "nonconstant ?p"
```
```  1505   from isnonconstant_pnormal_iff[OF inc, of bs] nc
```
```  1506   show "\<lparr>head p\<rparr>\<^sub>p\<^bsup>bs\<^esup> \<noteq> 0" unfolding nonconstant_def by blast
```
```  1507 next
```
```  1508   let ?p = "polypoly bs p"
```
```  1509   assume h: "\<lparr>head p\<rparr>\<^sub>p\<^bsup>bs\<^esup> \<noteq> 0"
```
```  1510   from isnonconstant_pnormal_iff[OF inc, of bs] h
```
```  1511   have pn: "pnormal ?p" by blast
```
```  1512   {fix x assume H: "?p = [x]"
```
```  1513     from H have "length (coefficients p) = 1" unfolding polypoly_def by auto
```
```  1514     with isnonconstant_coefficients_length[OF inc] have False by arith}
```
```  1515   thus "nonconstant ?p" using pn unfolding nonconstant_def by blast
```
```  1516 qed
```
```  1517
```
```  1518 lemma pnormal_length: "p\<noteq>[] \<Longrightarrow> pnormal p \<longleftrightarrow> length (pnormalize p) = length p"
```
```  1519   unfolding pnormal_def
```
```  1520  apply (induct p)
```
```  1521  apply (simp_all, case_tac "p=[]", simp_all)
```
```  1522  done
```
```  1523
```
```  1524 lemma degree_degree: assumes inc: "isnonconstant p"
```
```  1525   shows "degree p = Polynomial_List.degree (polypoly bs p) \<longleftrightarrow> \<lparr>head p\<rparr>\<^sub>p\<^bsup>bs\<^esup> \<noteq> 0"
```
```  1526 proof
```
```  1527   let  ?p = "polypoly bs p"
```
```  1528   assume H: "degree p = Polynomial_List.degree ?p"
```
```  1529   from isnonconstant_coefficients_length[OF inc] have pz: "?p \<noteq> []"
```
```  1530     unfolding polypoly_def by auto
```
```  1531   from H degree_coefficients[of p] isnonconstant_coefficients_length[OF inc]
```
```  1532   have lg:"length (pnormalize ?p) = length ?p"
```
```  1533     unfolding Polynomial_List.degree_def polypoly_def by simp
```
```  1534   hence "pnormal ?p" using pnormal_length[OF pz] by blast
```
```  1535   with isnonconstant_pnormal_iff[OF inc]
```
```  1536   show "\<lparr>head p\<rparr>\<^sub>p\<^bsup>bs\<^esup> \<noteq> 0" by blast
```
```  1537 next
```
```  1538   let  ?p = "polypoly bs p"
```
```  1539   assume H: "\<lparr>head p\<rparr>\<^sub>p\<^bsup>bs\<^esup> \<noteq> 0"
```
```  1540   with isnonconstant_pnormal_iff[OF inc] have "pnormal ?p" by blast
```
```  1541   with degree_coefficients[of p] isnonconstant_coefficients_length[OF inc]
```
```  1542   show "degree p = Polynomial_List.degree ?p"
```
```  1543     unfolding polypoly_def pnormal_def Polynomial_List.degree_def by auto
```
```  1544 qed
```
```  1545
```
```  1546 section{* Swaps ; Division by a certain variable *}
```
```  1547 primrec swap:: "nat \<Rightarrow> nat \<Rightarrow> poly \<Rightarrow> poly" where
```
```  1548   "swap n m (C x) = C x"
```
```  1549 | "swap n m (Bound k) = Bound (if k = n then m else if k=m then n else k)"
```
```  1550 | "swap n m (Neg t) = Neg (swap n m t)"
```
```  1551 | "swap n m (Add s t) = Add (swap n m s) (swap n m t)"
```
```  1552 | "swap n m (Sub s t) = Sub (swap n m s) (swap n m t)"
```
```  1553 | "swap n m (Mul s t) = Mul (swap n m s) (swap n m t)"
```
```  1554 | "swap n m (Pw t k) = Pw (swap n m t) k"
```
```  1555 | "swap n m (CN c k p) = CN (swap n m c) (if k = n then m else if k=m then n else k)
```
```  1556   (swap n m p)"
```
```  1557
```
```  1558 lemma swap: assumes nbs: "n < length bs" and mbs: "m < length bs"
```
```  1559   shows "Ipoly bs (swap n m t) = Ipoly ((bs[n:= bs!m])[m:= bs!n]) t"
```
```  1560 proof (induct t)
```
```  1561   case (Bound k) thus ?case using nbs mbs by simp
```
```  1562 next
```
```  1563   case (CN c k p) thus ?case using nbs mbs by simp
```
```  1564 qed simp_all
```
```  1565 lemma swap_swap_id[simp]: "swap n m (swap m n t) = t"
```
```  1566   by (induct t,simp_all)
```
```  1567
```
```  1568 lemma swap_commute: "swap n m p = swap m n p" by (induct p, simp_all)
```
```  1569
```
```  1570 lemma swap_same_id[simp]: "swap n n t = t"
```
```  1571   by (induct t, simp_all)
```
```  1572
```
```  1573 definition "swapnorm n m t = polynate (swap n m t)"
```
```  1574
```
```  1575 lemma swapnorm: assumes nbs: "n < length bs" and mbs: "m < length bs"
```
```  1576   shows "((Ipoly bs (swapnorm n m t) :: 'a\<Colon>{field_char_0, field_inverse_zero})) = Ipoly ((bs[n:= bs!m])[m:= bs!n]) t"
```
```  1577   using swap[OF prems] swapnorm_def by simp
```
```  1578
```
```  1579 lemma swapnorm_isnpoly[simp]:
```
```  1580     assumes "SORT_CONSTRAINT('a::{field_char_0, field_inverse_zero})"
```
```  1581   shows "isnpoly (swapnorm n m p)"
```
```  1582   unfolding swapnorm_def by simp
```
```  1583
```
```  1584 definition "polydivideby n s p =
```
```  1585     (let ss = swapnorm 0 n s ; sp = swapnorm 0 n p ; h = head sp; (k,r) = polydivide ss sp
```
```  1586      in (k,swapnorm 0 n h,swapnorm 0 n r))"
```
```  1587
```
```  1588 lemma swap_nz [simp]: " (swap n m p = 0\<^sub>p) = (p = 0\<^sub>p)" by (induct p, simp_all)
```
```  1589
```
```  1590 fun isweaknpoly :: "poly \<Rightarrow> bool"
```
```  1591 where
```
```  1592   "isweaknpoly (C c) = True"
```
```  1593 | "isweaknpoly (CN c n p) \<longleftrightarrow> isweaknpoly c \<and> isweaknpoly p"
```
```  1594 | "isweaknpoly p = False"
```
```  1595
```
```  1596 lemma isnpolyh_isweaknpoly: "isnpolyh p n0 \<Longrightarrow> isweaknpoly p"
```
```  1597   by (induct p arbitrary: n0, auto)
```
```  1598
```
```  1599 lemma swap_isweanpoly: "isweaknpoly p \<Longrightarrow> isweaknpoly (swap n m p)"
```
```  1600   by (induct p, auto)
```
```  1601
```
`  1602 end`