(* GCD for polynomials by the function package following GCD_Poly_ML *)

theory GCD_Poly_FP 

imports "HOL-Computational_Algebra.Polynomial"

        "HOL-Computational_Algebra.Primes"

begin

text \<open>

  This code has been translated from GCD_Poly_OLD.thy by Diana Meindl,

  who follows Franz Winkler, Polynomial algorithyms in computer algebra, Springer 1996.

  Winkler's original identifiers are in test/./gcd_poly_old.sml;

  test/../gcd_poly_ml.sml documents the changes towards GCD_Poly_ML.thy;

  the style of GCD_Poly_OLD.thy has been adapted to the function package.

\<close>

section \<open>Isabelle's predefined polynomials\<close>

\<comment> \<open>TODO\<close>

section \<open>gcd for univariate polynomials\<close>

type_synonym unipoly = "int list" (*TODO: compare Polynomial.thy*)

value "[0, 1, 2, 3, 4, 5] :: unipoly"

subsection \<open>auxiliary functions\<close>

(* a variant for div: 

  5 div 2 = 2; ~5 div 2 = ~3; BUT WEE NEED ~5 div2 2 = ~2; *)

definition div2 :: "int \<Rightarrow> int \<Rightarrow> int" (infixl "div2" 70) where

"a div2 b = (if a div b < 0 then (\<bar>a\<bar> div \<bar>b\<bar>) * -1 else a div b)"

value " 5 div2  2 =  2"

value "-5 div2  2 = -2"

value "-5 div2 -2 =  2"

value " 5 div2 -2 = -2"

value "gcd (15::int) (6::int) = 3"

value "gcd (10::int) (3::int) = 1"

value "gcd (6::int) (24::int) = 6"

(* drop tail elements equal 0 *)

primrec drop_hd_zeros :: "int list \<Rightarrow> int list" where

"drop_hd_zeros [] = []" |

"drop_hd_zeros (p # ps) = (if p = 0 then drop_hd_zeros ps else (p # ps))"

(* drop leading coefficients equal 0 *)

definition drop_tl_zeros :: "int list \<Rightarrow> int list" where

"drop_tl_zeros = rev o drop_hd_zeros o rev"

value "drop_tl_zeros [0, 1, 2, 3, 4, 5, 0, 0] = [0, 1, 2, 3, 4, 5]"

value "drop_tl_zeros [0, 1, 2, 3, 4, 5]       = [0, 1, 2, 3, 4, 5]"

subsection \<open>modulo calculations for integers\<close>

(* modi is just local for mod_inv *)

function modi :: "int \<Rightarrow> int \<Rightarrow> nat \<Rightarrow> nat \<Rightarrow> nat" where

"modi r rold m rinv = 

(if m \<le> rinv then 0 else

    if r mod (int m) = 1 

    then rinv 

    else modi (rold * ((int rinv) + 1)) rold m (rinv + 1))"

by auto

termination by (relation "measure (\<lambda>(r, rold, m, rinv). m - rinv)") auto

(* mod_inv :: int \<Rightarrow> nat \<Rightarrow> nat

   mod_inv r m = s

   assumes True

   yields r * s mod m = 1 *)

definition mod_inv :: "int \<Rightarrow> nat \<Rightarrow> nat" where "mod_inv r m = modi r r m 1"

value "modi 5 5 7 1   = 3"

value "modi 3 3 7 1   = 5"

value "modi 4 4 339 1 = 85"

value "mod_inv 5 7    = 3"

value "mod_inv 3 7    = 5"

value "mod_inv 4 339  = 85"

value "mod_inv (-5) 7    = 4"

value "mod_inv (-3) 7    = 2"

value "mod_inv (-4) 339  = 254"

(* mod_div :: int \<Rightarrow> int \<Rightarrow> nat \<Rightarrow> natO

   mod_div a b m = c

   assumes True

   yields a * b ^(-1) mod m = c   <\<Longrightarrow>  a mod m = (b * c) mod m*)

definition mod_div :: "int \<Rightarrow> int \<Rightarrow> nat \<Rightarrow> nat" where

"mod_div a b m = ((nat a) * (mod_inv b m)) mod m"

definition "ASSERT_mod_div1 \<longleftrightarrow> mod_div 21 4 5 = 4" ML \<open>@{assert} @{code ASSERT_mod_div1}\<close>

definition "ASSERT_mod_div2 \<longleftrightarrow> mod_div 1 4 5 = 4"  ML \<open>@{assert} @{code ASSERT_mod_div2}\<close>

definition "ASSERT_mod_div3 \<longleftrightarrow> mod_div 0 4 5 = 0"  ML \<open>@{assert} @{code ASSERT_mod_div3}\<close>

value "mod_div 21 3 5 = 2"            value "(21::int) mod 5 = (3 * 2) mod 5"

(*             21/3   = 7 mod 5               21       mod 5 =    6    mod 5

                      = 2                                  1               1 *)

value "mod_div 22 3 5 = 4"            value "(22::int) mod 5 = (3 * 4) mod 5"

(*             22/3   = -------               22       mod 5 =   12    mod 5

                      = 4                                  2               2 *)

value "mod_div 23 3 5 = 1"            value "(23::int) mod 5 = (3 * 1) mod 5"

(*             23/3   = -------               23       mod 5 =    3    mod 5

                      = 1                                  3               3 *)

value "mod_div 24 3 5 = 3"            value "(24::int) mod 5 = (3 * 3) mod 5"

(*             24/3   = -------               24       mod 5 =    9    mod 5

                      = 3                                  4               4 *)

value "mod_div 25 3 5 = 0"            value "(25::int) mod 5 = (3 * 0) mod 5"

(*             25/3   = -------               25       mod 5 =    0    mod 5

                      = 0                                  0               0 *)

value "mod_div 21 4 5 = 4"            value "(21::int) mod 5 = (4 * 4) mod 5"

value "mod_div  1 4 5 = 4"            value "( 1::int) mod 5 = (4 * 4) mod 5"

value "mod_div  0 4 5 = 0"            value "( 0::int) mod 5 = (0 * 4) mod 5"

(* root1 is just local to approx_root *)

function root1 :: "int \<Rightarrow> nat \<Rightarrow> nat" where

"root1 a n = (if (int (n * n)) < a then root1 a (n + 1) else n)"

by auto

termination sorry (*by (relation "measure (\<lambda>(a, n). nat (a - (int (n * n))))") auto*)

(* required just for one approximation:

   approx_root :: nat \<Rightarrow> nat

   approx_root a = r

   assumes True

   yields r * r \<ge> a *)

definition approx_root :: "int \<Rightarrow> nat" where "approx_root a = root1 a 1"

(* chinese_remainder :: int \<Rightarrow> int \<Rightarrow> int \<Rightarrow> int \<Rightarrow> int

   chinese_remainder (r1, m1) (r2, m2) = r

   assumes True

   yields r = r1 mod m1 \<and> r = r2 mod m2 *)

definition chinese_remainder :: "int \<Rightarrow> nat \<Rightarrow> int \<Rightarrow> nat \<Rightarrow> nat" where

"chinese_remainder r1 m1 r2 m2 = 

  ((nat (r1 mod (int m1))) + 

   (nat (((r2 - (r1 mod (int m1))) * (int (mod_inv (int m1) m2))) mod (int m2))) * 

  m1)"

value "chinese_remainder 17 9 3 4  = 35"

value "chinese_remainder  7 2 6 11 = 17"

subsection \<open>creation of lists of primes for efficiency\<close>

(* is_prime :: int list \<Rightarrow> int \<Rightarrow> bool

   is_prime ps n = b

   assumes max ps < n  \<and>  n \<le> (max ps)^2  \<and>  

     (*     FIXME: really ^^^^^^^^^^^^^^^? *)

     (\<forall>p. List.member ps p \<longrightarrow> Primes.prime p) \<and> (\<forall>p. p < n \<and> Primes.prime p \<longrightarrow> List.member ps p)

   yields Primes.prime n *)

fun is_prime :: "nat list \<Rightarrow> nat \<Rightarrow> bool" where

"is_prime ps n = 

(if List.length ps > 0

then 

  if (n mod (List.hd ps)) = 0

  then False

  else is_prime (List.tl ps) n

else True)"

declare is_prime.simps [simp del]     \<comment> \<open>make_primes, next_prime_not_dvd\<close>

value "is_prime [2, 3] 2  = False"    \<comment> \<open>... precondition!\<close>

value "is_prime [2, 3] 3  = False"    \<comment> \<open>... precondition!\<close>

value "is_prime [2, 3] 4  = False"

value "is_prime [2, 3] 5  = True"

value "is_prime [2, 3, 5] 5  = False" \<comment> \<open>... precondition!\<close>

value "is_prime [2, 3] 6  = False"

value "is_prime [2, 3] 7  = True"

value "is_prime [2, 3] 25 = True"     \<comment> \<open>... because 5 not in list\<close>

(* make_primes is just local to primes_upto only:

   make_primes :: int list \<Rightarrow> int \<Rightarrow> int \<Rightarrow> int list

   make_primes ps last_p n = pps

   assumes last_p = maxs ps  \<and>  (\<forall>p. List.member ps p \<longrightarrow> Primes.prime p)  \<and>

     (\<forall>p. p < last_p \<and> Primes.prime p \<longrightarrow> List.member ps p)

   yields n \<le> maxs pps  \<and>  (\<forall>p. List.member pps p \<longrightarrow> Primes.prime p)  \<and>

     (\<forall>p. (p < maxs pps \<and> Primes.prime p) \<longrightarrow> List.member pps p)*)

function make_primes :: "nat \<Rightarrow> nat \<Rightarrow> nat list \<Rightarrow> nat list" where

"make_primes last_p n ps =

  (if n \<le> last ps then ps

   else make_primes (last_p + 2) n 

    (if is_prime ps (last_p + 2) then ps @ [last_p + 2] else ps))"

by pat_completeness auto \<comment> \<open>simp del: is_prime.simps <-- declare\<close>

termination make_primes (*by lexicographic_order +PROOF primes? / size_change LOOPS*)

sorry \<comment> \<open>FIXME proof needs semantic properties of primes themselves\<close>

declare make_primes.simps [simp del] \<comment> \<open>next_prime_not_dvd\<close>

value "make_primes 3  3 [2, 3] = [2, 3]"

value "make_primes 3  4 [2, 3] = [2, 3, 5]"

value "make_primes 3  5 [2, 3] = [2, 3, 5]"

value "make_primes 3  6 [2, 3] = [2, 3, 5, 7]"

value "make_primes 3  7 [2, 3] = [2, 3, 5, 7]"

value "make_primes 3  8 [2, 3] = [2, 3, 5, 7, 11]"

value "make_primes 3  9 [2, 3] = [2, 3, 5, 7, 11]"

value "make_primes 3 10 [2, 3] = [2, 3, 5, 7, 11]"

value "make_primes 3 11 [2, 3] = [2, 3, 5, 7, 11]"

value "make_primes 3 12 [2, 3] = [2, 3, 5, 7, 11, 13]"

value "make_primes 3 13 [2, 3] = [2, 3, 5, 7, 11, 13]"

value "make_primes 3 14 [2, 3] = [2, 3, 5, 7, 11, 13, 17]"

value "make_primes 3 15 [2, 3] = [2, 3, 5, 7, 11, 13, 17]"

value "make_primes 3 16 [2, 3] = [2, 3, 5, 7, 11, 13, 17]"

value "make_primes 3 17 [2, 3] = [2, 3, 5, 7, 11, 13, 17]"

value "make_primes 3 18 [2, 3] = [2, 3, 5, 7, 11, 13, 17, 19]"

value "make_primes 3 19 [2, 3] = [2, 3, 5, 7, 11, 13, 17, 19]"

value "make_primes 7 4 [2, 3, 5, 7] = [2, 3, 5, 7]"

(* primes_upto :: nat \<Rightarrow> nat list

   primes_upto n = ps

     assumes True

     yields (\<forall>p. List.member ps p \<longrightarrow> Primes.prime p) \<and>

       n \<le> maxs ps \<and> maxs ps \<le> Fact.fact n + 1 \<and>

       (\<forall>p. p \<le> maxs ps \<and> Primes.prime p \<longrightarrow> List.member ps p) *)

definition primes_upto :: "nat \<Rightarrow> nat list" where

"primes_upto n = (if n < 3 then [2] else make_primes 3 n [2, 3])"

value "primes_upto  0 = [2]"

value "primes_upto  1 = [2]"

value "primes_upto  2 = [2]"

value "primes_upto  3 = [2, 3]"

value "primes_upto  4 = [2, 3, 5]"

value "primes_upto  5 = [2, 3, 5]"

value "primes_upto  6 = [2, 3, 5, 7]"

value "primes_upto  7 = [2, 3, 5, 7]"

value "primes_upto  8 = [2, 3, 5, 7, 11]"

value "primes_upto  9 = [2, 3, 5, 7, 11]"

value "primes_upto 10 = [2, 3, 5, 7, 11]"

value "primes_upto 11 = [2, 3, 5, 7, 11]"

lemma primes_upto_0: "last (primes_upto n) > 0" (*see above*) sorry

lemma primes_upto_1: "last (primes_upto (Suc n)) > n" (*see above*)

  apply (simp add: primes_upto_def)

  apply (induct rule: make_primes.induct)

  apply auto (*... same problems as with "make_primes" *)

 sorry

lemma primes_upto_2: "last (primes_upto n) >= n" (*see above*) sorry

(* max's' is analogous to Integer.gcds; used ONLY in specifications, not in functions *)

definition maxs :: "nat list \<Rightarrow> nat" where "maxs ns = List.fold max ns (List.hd ns)"

value "maxs [5, 3, 7, 1, 2, 4] = 7"

(* find the next prime greater p not dividing the number n:

  next_prime_not_dvd :: int \<Rightarrow> int \<Rightarrow> int (infix)

  n1 next_prime_not_dvd n2 = p

    assumes True  assumes "0 < q" 

    yields p is_prime  \<and>  n1 < p  \<and>  \<not> p dvd n2  \<and> (* smallest with these properties... *)

      (\<forall> p'. (p' is_prime  \<and>  n1 < p'  \<and>  \<not> p' dvd n2)  \<longrightarrow>  p \<le> p') *)

function next_prime_not_dvd :: "nat \<Rightarrow> nat \<Rightarrow> nat" (*infixl "next_prime_not_dvd" 70*) where

"next_prime_not_dvd n1 n2 = 

(let

  ps = primes_upto (n1 + 1);

  nxt = last ps

in

  if n2 mod nxt \<noteq> 0

  then nxt

  else next_prime_not_dvd nxt n2)"

by auto \<comment> \<open>simp del: is_prime.simps, make_primes.simps, primes_upto.simps < -- declare*\<close>

termination sorry (*next_prime_not_dvd: lexicographic_order  +PROOF primes? / size_change: Failed*)

value "next_prime_not_dvd 1 15 = 2"

value "next_prime_not_dvd 2 15 = 7"

value "next_prime_not_dvd 3 15 = 7"

value "next_prime_not_dvd 4 15 = 7"

value "next_prime_not_dvd 5 15 = 7"

value "next_prime_not_dvd 6 15 = 7"

value "next_prime_not_dvd 7 15 =11"

subsection \<open>basic notions for univariate polynomials\<close>

(* not in List.thy, copy from library.ML *)

fun nth_drop :: "nat \<Rightarrow> 'a list \<Rightarrow> 'a list" where

"nth_drop n xs = List.take n xs @ List.drop (n + 1) xs"

value "nth_drop 0 []              = []"

value "nth_drop 0 [1, 2, 3::int]  = [2, 3]"

value "nth_drop 2 [1, 2, 3::int]  = [1, 2]"

value "nth_drop 77 [1, 2, 3::int] = [1, 2, 3]"

(* leading coefficient *)

definition lcoeff_up :: "unipoly \<Rightarrow> int" where "lcoeff_up p = (last o drop_tl_zeros) p"

value "lcoeff_up [3, 4, 5, 6]    = 6"

value "lcoeff_up [3, 4, 5, 6, 0] = 6"

(* degree *)

definition deg_up :: "unipoly \<Rightarrow> nat" where

  "deg_up p = ((\<lambda>k. k - 1) o length o drop_tl_zeros) p"

  (* FH wrong:    (op - 1) o *)

value "degree (Coeff [1::int, 2, 3])"

value "deg_up [1, 2, 3]"

value "deg_up [3, 4, 5, 6]    = 3"

value "deg_up [3, 4, 5, 6, 0] = 3"

value "deg_up [1, 0, 3, 0, 0] = 2"

(* norm is just local to normalise *)

fun norm :: "unipoly \<Rightarrow> unipoly \<Rightarrow> nat \<Rightarrow> int \<Rightarrow> nat \<Rightarrow> unipoly" where

"norm p nrm m lcp i = 

(if i = 0

  then [int (mod_div (p ! i) lcp m)] @ nrm

  else norm p ([int (mod_div (p ! i) lcp m)] @ nrm) m lcp (i - 1))"

(* normalise a unipoly such that lcoeff_up mod m = 1.

   normalise :: unipoly \<Rightarrow> nat \<Rightarrow> unipoly

   normalise [p_0, .., p_k] m = [q_0, .., q_k]

     assumes 

     yields \<exists> t. 0 \<le> i \<le> k \<Rightarrow> (p_i * t) mod m = q_i  \<and>  (p_k * t) mod m = 1 *)

fun normalise :: "unipoly \<Rightarrow> nat \<Rightarrow> unipoly" where

"normalise p m = 

(let

 p = drop_tl_zeros p;

 lcp = lcoeff_up p

in 

  if List.length p = 0 then [] else norm p [] m lcp (List.length p - 1))"

declare normalise.simps [simp del] \<comment> \<open>HENSEL_lifting_up\<close>

value "normalise [-18, -15, -20, 12, 20, -13, 2] 5 = [1, 0, 0, 1, 0, 1, 1]"

value "normalise [9, 6, 3] 10                      = [3, 2, 1]"

subsection \<open>addition, multiplication, division\<close>

(* scalar multiplication *)

definition  mult_ups :: "unipoly \<Rightarrow> int \<Rightarrow> unipoly" (infixl "%*" 70) where

"p %* m = List.map (\<lambda>i. m * i) p"

value "[5, 4, 7, 8, 1] %* 5   = [25, 20, 35, 40, 5]"

value "[5, 4, -7, 8, -1] %* 5 = [25, 20, -35, 40, -5]"

(* scalar divison *)

(*definition swapf :: "('a \<Rightarrow> 'b \<Rightarrow> 'c) \<Rightarrow> 'b \<Rightarrow> 'a \<Rightarrow> 'c" where "swapf f a b = f b a"

CODEGEN CAUSES ERROR:

ML error (line 913 of "/home/neuper/devel/isac/codegen/gcd_univariate.sml"):

Type error in function application. Function: div2 : inta -> inta -> inta

   Argument: (swapf, m) : (('a -> 'b -> 'c) -> 'b -> 'a -> 'c) * 'd

   Reason: Can't unify inta to (('a -> 'b -> 'c) -> 'b -> 'a -> 'c) * 'd (Incompatible types)

THUS TYPE CONSTRAINED...

*)

definition div_ups :: "unipoly \<Rightarrow> int \<Rightarrow> unipoly" (infixl "%'/" 70) where

"p %/ m = map (\<lambda>i. i div2 m) p"

value "[4, 3, 2, 5, 6] %/ 3 = [1, 1, 0, 1, 2]"

value "[4, 3, 2, 0] %/ 3    = [1, 1, 0, 0]"

(* not in List.thy, copy from library.ML *)

fun map2 :: "('a \<Rightarrow> 'b \<Rightarrow> 'c) \<Rightarrow> 'a list \<Rightarrow> 'b list \<Rightarrow> 'c list" where

"map2 _ [] [] = []" |

"map2 f (x # xs) (y # ys) = f x y # map2 f xs ys" |

"map2 _ _ _ = []" (*raise ListPair.UnequalLengths*)

(* minus of polys *)

definition minus_up :: "unipoly \<Rightarrow> unipoly \<Rightarrow> unipoly" (infixl "%-%" 70) where

"p1 %-% p2 = map2 (\<lambda>i j. i - j) p1 p2"

value "[8, -7, 0, 1] %-% [-2, 2, 3, 0]     = [10, -9, -3, 1]"

value "[8, 7, 6, 5, 4] %-% [2, 2, 3, 1, 1] = [6, 5, 3, 4, 3]"

function (sequential) dvd_up :: "unipoly \<Rightarrow> unipoly \<Rightarrow> bool" (infixl "%|%" 70) where

"[d] %|% [p] \<longleftrightarrow> (\<bar>d\<bar> \<le> \<bar>p\<bar>) \<and> (p mod d = 0)" | 

"ds %|% ps \<longleftrightarrow>   \<comment> \<open>a hint by FH\<close>

  (let 

    ds = drop_tl_zeros ds; ps = drop_tl_zeros ps;

    d000 = (List.replicate (List.length ps - List.length ds) 0) @ ds;

    quot = (lcoeff_up ps) div2 (lcoeff_up d000);

    rest = drop_tl_zeros (ps %-% (d000 %* quot))

  in

    rest = [] \<or> (quot \<noteq> 0 \<and> List.length ds \<le> List.length rest \<and> ds %|% rest))"

apply pat_completeness

apply simp+

done (* > 1 sec IMPROVED BY FLORIAN'S drop_tl_zeros AND declare simp del: 

  centr_up_def normalise.simps mod_up_gcd.simps lcoeff_up.simps*)

termination (*dvd_up: by lexicographic_order LOOPS  +PROOF primes? / size_change LOOPS*)

using [[linarith_split_limit = 999]]

apply (relation "measure (\<lambda>(_, ps). length ps)") (*a hint by FH*)

apply auto

sorry 

value "[4] %|% [6]                 = False"

value "[8] %|% [16, 0]             = True"

value "[3, 2] %|% [0, 0, 9, 12, 4] = True"

value "[8, 0] %|% [16]             = True"

subsection \<open>normalisation and Landau-Mignotte bound\<close>

(* centr is just local to centr_up *)

definition centr :: "nat \<Rightarrow> int \<Rightarrow> int \<Rightarrow> int" where

"centr m mid p_i = (if mid < p_i then p_i - (int m) else p_i)"

(* normalise :: centr_up \<Rightarrow> unipoly => int \<Rightarrow> unipoly

   normalise [p_0, .., p_k] m = [q_0, .., q_k]

     assumes 

     yields 0 \<le> i \<le> k \<Rightarrow> |^ ~m/2 ^| <= q_i <=|^ m/2 ^| 

      (where |^ x ^| means round x up to the next greater integer) *)

definition centr_up :: "unipoly \<Rightarrow> nat \<Rightarrow> unipoly" where

"centr_up p m =

(let

  mi = (int m) div2 2;

  mid = if (int m) mod mi = 0 then mi else mi + 1

in map (centr m mid) p)"

value "centr_up [7, 3, 5, 8, 1, 3] 10 = [-3, 3, 5, -2, 1, 3]"

value "centr_up [1, 2, 3, 4, 5] 2     = [1, 0, 1, 2, 3]"

value "centr_up [1, 2, 3, 4, 5] 3     = [1, -1, 0, 1, 2]"

value "centr_up [1, 2, 3, 4, 5] 4     = [1, 2, -1, 0, 1]"

value "centr_up [1, 2, 3, 4, 5] 5     = [1, 2, 3, -1, 0]"

value "centr_up [1, 2, 3, 4, 5] 6     = [1, 2, 3, -2, -1]"

value "centr_up [1, 2, 3, 4, 5] 7     = [1, 2, 3, 4, -2]"

value "centr_up [1, 2, 3, 4, 5] 8     = [1, 2, 3, 4, -3]"

value "centr_up [1, 2, 3, 4, 5] 9     = [1, 2, 3, 4, 5]"

value "centr_up [1, 2, 3, 4, 5] 10    = [1, 2, 3, 4, 5]"

value "centr_up [1, 2, 3, 4, 5] 11    = [1, 2, 3, 4, 5]"

(* sum_lmb :: centr_up \<Rightarrow> unipoly \<Rightarrow> int \<Rightarrow> int

   sum_lmb [p_0, .., p_k] e = s

     assumes exp >= 0

     yields. p_0^e + p_1^e + ... + p_k^e *)

definition sum_lmb :: "unipoly \<Rightarrow> nat \<Rightarrow> int" where

"sum_lmb p e = List.fold ((\<lambda>i. (+) i) o (\<lambda>i.  i ^ e)) p 0"

value "sum_lmb [-1, 2, -3, 4, -5] 1 = -3"

value "sum_lmb [-1, 2, -3, 4, -5] 2 = 55"

value "sum_lmb [-1, 2, -3, 4, -5] 3 = -81"

value "sum_lmb [-1, 2, -3, 4, -5] 4 = 979"

value "sum_lmb [-1, 2, -3, 4, -5] 5 = -2313"

value "sum_lmb [-1, 2, -3, 4, -5] 6 = 20515"

(* LANDAU_MIGNOTTE_bound :: centr_up \<Rightarrow> unipoly => unipoly \<Rightarrow> int

   LANDAU_MIGNOTTE_bound [a_0, ..., a_m] [b_0, .., b_n] = lmb

     assumes True

     yields lmb = 2^min(m,n) * gcd(a_m,b_n) * 

       min( 1/|a_m| * root(sum_lmb [a_0,...a_m] 2 , 1/|b_n| * root(sum_lmb [b_0,...b_n] 2)*)

definition LANDAU_MIGNOTTE_bound :: "unipoly \<Rightarrow> unipoly \<Rightarrow> nat" where

"LANDAU_MIGNOTTE_bound p1 p2 =

  ((power 2 (min (deg_up p1) (deg_up p2))) * (nat (gcd (lcoeff_up p1) (lcoeff_up p2))) * 

  (nat (min (abs ((int (approx_root (sum_lmb p1 2))) div2 -(lcoeff_up p1)))

            (abs ((int (approx_root (sum_lmb p2 2))) div2 -(lcoeff_up p2))))))"

value "LANDAU_MIGNOTTE_bound [1] [4, 5]          = 1"

value "LANDAU_MIGNOTTE_bound [1, 2] [4, 5]       = 2"

value "LANDAU_MIGNOTTE_bound [1, 2, 3] [4, 5]    = 2"

value "LANDAU_MIGNOTTE_bound [1, 2, 3] [4]       = 1"

value "LANDAU_MIGNOTTE_bound [1, 2, 3] [4, 5]    = 2"

value "LANDAU_MIGNOTTE_bound [1, 2, 3] [4, 5, 6] = 12"

value "LANDAU_MIGNOTTE_bound [-1] [4, 5]            = 1"

value "LANDAU_MIGNOTTE_bound [-1, 2] [4, 5]         = 2"

value "LANDAU_MIGNOTTE_bound [-1, 2, -3] [4, -5]    = 2"

value "LANDAU_MIGNOTTE_bound [-1, 2, -3] [4]        = 1"

value "LANDAU_MIGNOTTE_bound [-1, 2, -3] [4, -5]    = 2"

value "LANDAU_MIGNOTTE_bound [-1, 2, -3] [4, -5, 6] = 12"

subsection \<open>modulo calculations for polynomials\<close>

(* pair is just local to chinese_remainder_up, is "op ~~" in library.ML *)

fun pair :: "unipoly \<Rightarrow> unipoly \<Rightarrow> ((int \<times> int) list)" (infix "pair" 4) where

"([] pair []) = []" |

"([] pair ys) = []" | (*raise ListPair.UnequalLengths*)

"(xs pair []) = []" | (*raise ListPair.UnequalLengths*)

"((x#xs) pair (y#ys)) = (x, y) # (xs pair ys)"

fun chinese_rem :: "nat \<times> nat \<Rightarrow> int \<times> int \<Rightarrow> int" where

"chinese_rem (m1, m2) (p1, p2) = (int (chinese_remainder p1 m1 p2 m2))"

  (* chinese_remainder_up :: int * int \<Rightarrow> unipoly * unipoly \<Rightarrow> unipoly

     chinese_remainder_up (m1, m2) (p1, p2) = p

     assume m1, m2 relatively prime

     yields p1 = p mod m1 \<and> p2 = p mod m2 *)

fun chinese_remainder_up :: "nat \<times> nat \<Rightarrow> unipoly \<times> unipoly \<Rightarrow> unipoly" where

"chinese_remainder_up (m1, m2) (p1, p2) = map (chinese_rem (m1, m2)) (p1 pair p2)"

value "chinese_remainder_up (5, 7) ([2, 2, 4, 3], [3, 2, 3, 5]) = [17, 2, 24, 33]"

(* mod_up :: unipoly \<Rightarrow> int \<Rightarrow> unipoly

   mod_up [p1, p2, ..., pk] m = up 

   assume m > 0

   yields up = [p1 mod m, p2 mod m, ..., pk mod m]*)

definition mod' :: "nat \<Rightarrow> int \<Rightarrow> int" where "mod' m i = i mod (int m)"

definition mod_up :: "unipoly \<Rightarrow> nat \<Rightarrow> unipoly" (*infixl "mod_up" 70*) where

"mod_up p m = map (mod' m) p"

value "mod_up [5, 4, 7, 8, 1] 5 = [0, 4, 2, 3, 1]"

value "mod_up [5, 4,-7, 8,-1] 5 = [0, 4, 3, 3, 4]"

(* euclidean algoritm in Z_p[x/m].

   mod_up_gcd :: unipoly \<Rightarrow> unipoly \<Rightarrow> nat \<Rightarrow> unipoly

   mod_up_gcd p1 p2 m = g

     assumes 

     yields  gcd (p1 mod m) (p2 mod m) = g *)

function mod_up_gcd :: "unipoly \<Rightarrow> unipoly  \<Rightarrow> nat \<Rightarrow> unipoly" where

"mod_up_gcd p1 p2 m = 

(let 

  p1m = mod_up p1 m;

  p2m = drop_tl_zeros (mod_up p2 m);

  p2n = (replicate (List.length p1 - List.length p2m) 0) @ p2m;

  quot = mod_div (lcoeff_up p1m) (lcoeff_up p2n) m;

  rest = drop_tl_zeros (mod_up (p1m %-% (p2n %* (int quot))) m)

in 

  if rest = [] then p2 else

    if List.length rest < List.length p2

    then mod_up_gcd p2 rest m 

    else mod_up_gcd rest p2 m)"

by auto

termination mod_up_gcd (*by lexicographic_order +PROOF primes? / size_change LOOPS*)

sorry

declare mod_up_gcd.simps [simp del] \<comment> \<open>HENSEL_lifting_up\<close>

value "mod_up_gcd [-18, -15, -20, 12, 20, -13, 2] [8, 28, 22, -11, -14, 1, 2] 7 = [2, 6, 0, 2, 6]" 

value "mod_up_gcd [8, 28, 22, -11, -14, 1, 2] [2, 6, 0, 2, 6] 7 = [2, 6, 0, 2, 6]" 

value "mod_up_gcd [20, 15, 8, 6] [8, -2, -2, 3] 2 = [0, 1]"

  value "[20, 15, 8, 6] %|% [0, 1] = False"

  value "[8, -2, -2, 3] %|% [0, 1] = False"

(* analogous to Integer.gcds 

  gcds :: int list \<Rightarrow> int

  gcds ns = d

  assumes True

  yields THE d. ((\<forall>n. List.member ns n \<longrightarrow> d dvd n) \<and>

    (\<forall>d'. (\<forall>n. List.member ns n \<and> d' dvd n) \<longrightarrow> d'modp \<le> d)) *)

fun gcds :: "int list \<Rightarrow> int" where "gcds ns = List.fold gcd ns (List.hd ns)" (*FH Gcd, set ?*)

value "gcds [6, 9, 12] = 3"

value "gcds [6, -9, 12] = 3"

value "gcds [8, 12, 16] = 4"

value "gcds [-8, 12, -16] = 4"

(* prim_poly :: unipoly \<Rightarrow> unipoly

   prim_poly p = pp

   assumes True

   yields \<forall>p1, p2. (List.member pp p1 \<and> List.member pp p2 \<and> p1 \<noteq> p2) \<longrightarrow> gcd p1 p2 = 1 *)

fun primitive_up :: "unipoly \<Rightarrow> unipoly" where

"primitive_up [c] = (if c = 0 then [0] else [1])" |

"primitive_up p =

  (let d = gcds p

  in

    if d = 1 then p else p %/ d)"

value "primitive_up [12, 16, 32, 44] = [3, 4, 8, 11]"

value "primitive_up [4, 5, 12] =  [4, 5, 12]"

value "primitive_up [0] = [0]"

value "primitive_up [6] = [1]"

subsection \<open>gcd_up, code from [1] p.93\<close>

(* try_new_prime_up :: unipoly \<Rightarrow> unipoly \<Rightarrow> int \<Rightarrow> int \<Rightarrow> int \<Rightarrow> unipoly \<Rightarrow> int  \<Rightarrow> unipoly

   try_new_prime_up a b d M P g p = new_g

     assumes d = gcd (lcoeff_up a, lcoeff_up b)  \<and> 

             M = LANDAU_MIGNOTTE_bound  \<and>  p = prime  \<and>  p ~| d  \<and>  P \<ge> p  \<and>

             a is primitive  \<and>  b is primitive

     yields  new_g = [1] \<or> (new_g \<ge> g \<and> P > M)

  argumentns "a b d M P g p" named according to [1] p.93: "p" is "prime", not "poly" ! *)

function try_new_prime_up :: "unipoly \<Rightarrow> unipoly \<Rightarrow> nat \<Rightarrow> nat \<Rightarrow> nat \<Rightarrow> unipoly \<Rightarrow> nat \<Rightarrow> unipoly" 

where 

"try_new_prime_up             a          b          d      M      P     g          p   = 

(if P > M then g else 

  let p = next_prime_not_dvd p d;

      g_p = centr_up (mod_up (    (normalise (mod_up_gcd a b p) p)

                                %* (int (d mod p)))p)

                     p

  in

    if deg_up g_p < deg_up g

    then 

      if (deg_up g_p) = 0 then [1] else try_new_prime_up a b d M p g_p p

    else 

      if deg_up g_p \<noteq> deg_up g then try_new_prime_up a b d M P g p else

        let 

          P = P * p;

          g = centr_up (mod_up (chinese_remainder_up (P, p) (g, g_p)) P) P

        in try_new_prime_up a b d M P g p)"

by pat_completeness auto \<comment> \<open>simp del: centr_up_def normalise.simps mod_up_gcd.simps\<close>

termination try_new_prime_up (*by lexicographic_order +PROOF primes? / by size_change LOOPS*)

sorry

(* HENSEL_lifting_up :: unipoly \<Rightarrow> unipoly \<Rightarrow> int \<Rightarrow> int \<Rightarrow> int \<Rightarrow> unipoly

   HENSEL_lifting_up p1 p2 d M p = gcd

     assumes d = gcd (lcoeff_up p1, lcoeff_up p2) \<and> 

             M = LANDAU_MIGNOTTE_bound \<and> p = prime  \<and>  p ~| d  \<and>

             p1 is primitive  \<and>  p2 is primitive

     yields  gcd | p1  \<and>  gcd | p2  \<and>  gcd is primitive

  argumentns "a b d M p" named according to [1] p.93: "p" is "prime", not "poly" ! *)

function HENSEL_lifting_up :: "unipoly \<Rightarrow> unipoly \<Rightarrow> nat \<Rightarrow> nat \<Rightarrow> nat \<Rightarrow> unipoly" where

"HENSEL_lifting_up a b d M p = 

(let

  p = next_prime_not_dvd p d;

  g_p = centr_up (mod_up ((normalise (mod_up_gcd a b p) p) %* (int (d mod p))) p) p \<comment> \<open>see above\<close>

in 

  if deg_up g_p = 0 then [1] else 

    (let 

      g = primitive_up (try_new_prime_up a b d M p g_p p)

    in

      if (g %|% a) \<and> (g %|% b) then g else HENSEL_lifting_up a b d M p))"

by pat_completeness auto \<comment> \<open>simp del: centr_up_def normalise.simps mod_up_gcd.simps\<close>

termination HENSEL_lifting_up (*by lexicographic_order LOOPS +PROOF primes? / by size_change LOOPS*)

sorry 

(* gcd_up :: unipoly \<Rightarrow> unipoly \<Rightarrow> unipoly

   gcd_up a b = c

   assumes not (a = [] \<or> a = [0]) \<and> not (b = []\<or> b = [0]) \<and> 

           a is primitive \<and> b is primitive

   yields c dvd a \<and> c dvd b \<and> (\<forall>c'. (c' dvd a \<and> c' dvd b) \<longrightarrow> c' \<le> c) *)

function gcd_up :: "unipoly \<Rightarrow> unipoly \<Rightarrow> unipoly" where

"gcd_up a b = 

(let d = \<bar>gcd (lcoeff_up a) (lcoeff_up b)\<bar>

in

  if a = b then a else

    HENSEL_lifting_up a b (nat d) (2 * (nat d) * LANDAU_MIGNOTTE_bound a b) 1)"

by pat_completeness auto \<comment> \<open>simp del: lcoeff_up.simps ?+ others?\<close>

termination by lexicographic_order (*works*)

ML \<open>"----------- fun gcd_up ---------------------------------";\<close>

value "gcd_up [-18, -15, -20, 12, 20, -13, 2] [8, 28, 22, -11, -14, 1, 2] = [-2, -1, 1]"

definition "ASSERT_gcd_up1 \<longleftrightarrow> 

  gcd_up [-18, -15, -20, 12, 20, -13, 2] [8, 28, 22, -11, -14, 1, 2] = [-2, -1, 1]"

ML \<open>@{assert} @{code ASSERT_gcd_up1}\<close>

(*     gcd    (-1 + x^2) (x + x^2) = (1 + x) ...*)

value "gcd_up [-1, 0 ,1] [0, 1, 1] = [1, 1]"

definition "ASSERT_gcd_up2 \<longleftrightarrow> gcd_up [-1, 0 ,1] [0, 1, 1] = [1, 1]"

ML \<open>@{assert} @{code ASSERT_gcd_up2}\<close>

(*

print_configs

declare [[simp_trace_depth_limit = 99]]

declare [[simp_trace = true]]

using [[simp_trace_depth_limit = 99]]

using [[simp_trace = true]]

*)

end