src/HOL/ex/Normalization_by_Evaluation.thy
author krauss
Tue, 28 Sep 2010 09:54:07 +0200
changeset 39754 150f831ce4a3
parent 39395 a1aa9fbcbd3d
child 40730 2aa0390a2da7
permissions -rw-r--r--
no longer declare .psimps rules as [simp]. This regularly caused confusion (e.g., they show up in simp traces when the regular simp rules are disabled). In the few places where the rules are used, explicitly mentioning them actually clarifies the proof text.

(*  Authors:  Klaus Aehlig, Tobias Nipkow *)

header {* Testing implementation of normalization by evaluation *}

theory Normalization_by_Evaluation
imports Complex_Main
begin

lemma "True" by normalization
lemma "p \<longrightarrow> True" by normalization
declare disj_assoc [code nbe]
lemma "((P | Q) | R) = (P | (Q | R))" by normalization
lemma "0 + (n::nat) = n" by normalization
lemma "0 + Suc n = Suc n" by normalization
lemma "Suc n + Suc m = n + Suc (Suc m)" by normalization
lemma "~((0::nat) < (0::nat))" by normalization

datatype n = Z | S n

primrec add :: "n \<Rightarrow> n \<Rightarrow> n" where
   "add Z = id"
 | "add (S m) = S o add m"

primrec add2 :: "n \<Rightarrow> n \<Rightarrow> n" where
   "add2 Z n = n"
 | "add2 (S m) n = S(add2 m n)"

declare add2.simps [code]
lemma [code nbe]: "add2 (add2 n m) k = add2 n (add2 m k)"
  by (induct n) auto
lemma [code]: "add2 n (S m) =  S (add2 n m)"
  by(induct n) auto
lemma [code]: "add2 n Z = n"
  by(induct n) auto

lemma "add2 (add2 n m) k = add2 n (add2 m k)" by normalization
lemma "add2 (add2 (S n) (S m)) (S k) = S(S(S(add2 n (add2 m k))))" by normalization
lemma "add2 (add2 (S n) (add2 (S m) Z)) (S k) = S(S(S(add2 n (add2 m k))))" by normalization

primrec mul :: "n \<Rightarrow> n \<Rightarrow> n" where
   "mul Z = (%n. Z)"
 | "mul (S m) = (%n. add (mul m n) n)"

primrec mul2 :: "n \<Rightarrow> n \<Rightarrow> n" where
   "mul2 Z n = Z"
 | "mul2 (S m) n = add2 n (mul2 m n)"

primrec exp :: "n \<Rightarrow> n \<Rightarrow> n" where
   "exp m Z = S Z"
 | "exp m (S n) = mul (exp m n) m"

lemma "mul2 (S(S(S(S(S Z))))) (S(S(S Z))) = S(S(S(S(S(S(S(S(S(S(S(S(S(S(S Z))))))))))))))" by normalization
lemma "mul (S(S(S(S(S Z))))) (S(S(S Z))) = S(S(S(S(S(S(S(S(S(S(S(S(S(S(S Z))))))))))))))" by normalization
lemma "exp (S(S Z)) (S(S(S(S Z)))) = exp (S(S(S(S Z)))) (S(S Z))" by normalization

lemma "(let ((x,y),(u,v)) = ((Z,Z),(Z,Z)) in add (add x y) (add u v)) = Z" by normalization
lemma "split (%x y. x) (a, b) = a" by normalization
lemma "(%((x,y),(u,v)). add (add x y) (add u v)) ((Z,Z),(Z,Z)) = Z" by normalization

lemma "case Z of Z \<Rightarrow> True | S x \<Rightarrow> False" by normalization

lemma "[] @ [] = []" by normalization
lemma "map f [x,y,z::'x] = [f x, f y, f z]" by normalization
lemma "[a, b, c] @ xs = a # b # c # xs" by normalization
lemma "[] @ xs = xs" by normalization
lemma "map (%f. f True) [id, g, Not] = [True, g True, False]" by normalization

lemma "map (%f. f True) ([id, g, Not] @ fs) = [True, g True, False] @ map (%f. f True) fs"
  by normalization rule+
lemma "rev [a, b, c] = [c, b, a]" by normalization
value [nbe] "rev (a#b#cs) = rev cs @ [b, a]"
value [nbe] "map (%F. F [a,b,c::'x]) (map map [f,g,h])"
value [nbe] "map (%F. F ([a,b,c] @ ds)) (map map ([f,g,h]@fs))"
value [nbe] "map (%F. F [Z,S Z,S(S Z)]) (map map [S,add (S Z),mul (S(S Z)),id])"
lemma "map (%x. case x of None \<Rightarrow> False | Some y \<Rightarrow> True) [None, Some ()] = [False, True]" 
  by normalization
value [nbe] "case xs of [] \<Rightarrow> True | x#xs \<Rightarrow> False"
value [nbe] "map (%x. case x of None \<Rightarrow> False | Some y \<Rightarrow> True) xs = P"
lemma "let x = y in [x, x] = [y, y]" by normalization
lemma "Let y (%x. [x,x]) = [y, y]" by normalization
value [nbe] "case n of Z \<Rightarrow> True | S x \<Rightarrow> False"
lemma "(%(x,y). add x y) (S z,S z) = S (add z (S z))" by normalization
value [nbe] "filter (%x. x) ([True,False,x]@xs)"
value [nbe] "filter Not ([True,False,x]@xs)"

lemma "[x,y,z] @ [a,b,c] = [x, y, z, a, b, c]" by normalization
lemma "(%(xs, ys). xs @ ys) ([a, b, c], [d, e, f]) = [a, b, c, d, e, f]" by normalization
lemma "map (%x. case x of None \<Rightarrow> False | Some y \<Rightarrow> True) [None, Some ()] = [False, True]" by normalization

lemma "last [a, b, c] = c" by normalization
lemma "last ([a, b, c] @ xs) = last (c # xs)" by normalization

lemma "(2::int) + 3 - 1 + (- k) * 2 = 4 + - k * 2" by normalization
lemma "(-4::int) * 2 = -8" by normalization
lemma "abs ((-4::int) + 2 * 1) = 2" by normalization
lemma "(2::int) + 3 = 5" by normalization
lemma "(2::int) + 3 * (- 4) * (- 1) = 14" by normalization
lemma "(2::int) + 3 * (- 4) * 1 + 0 = -10" by normalization
lemma "(2::int) < 3" by normalization
lemma "(2::int) <= 3" by normalization
lemma "abs ((-4::int) + 2 * 1) = 2" by normalization
lemma "4 - 42 * abs (3 + (-7\<Colon>int)) = -164" by normalization
lemma "(if (0\<Colon>nat) \<le> (x\<Colon>nat) then 0\<Colon>nat else x) = 0" by normalization
lemma "4 = Suc (Suc (Suc (Suc 0)))" by normalization
lemma "nat 4 = Suc (Suc (Suc (Suc 0)))" by normalization
lemma "[Suc 0, 0] = [Suc 0, 0]" by normalization
lemma "max (Suc 0) 0 = Suc 0" by normalization
lemma "(42::rat) / 1704 = 1 / 284 + 3 / 142" by normalization
value [nbe] "Suc 0 \<in> set ms"

lemma "f = f" by normalization
lemma "f x = f x" by normalization
lemma "(f o g) x = f (g x)" by normalization
lemma "(f o id) x = f x" by normalization
value [nbe] "(\<lambda>x. x)"

(* Church numerals: *)

value [nbe] "(%m n f x. m f (n f x)) (%f x. f(f(f(x)))) (%f x. f(f(f(x))))"
value [nbe] "(%m n f x. m (n f) x) (%f x. f(f(f(x)))) (%f x. f(f(f(x))))"
value [nbe] "(%m n. n m) (%f x. f(f(f(x)))) (%f x. f(f(f(x))))"

(* handling of type classes in connection with equality *)

lemma "map f [x, y] = [f x, f y]" by normalization
lemma "(map f [x, y], w) = ([f x, f y], w)" by normalization
lemma "map f [x, y] = [f x \<Colon> 'a\<Colon>semigroup_add, f y]" by normalization
lemma "map f [x \<Colon> 'a\<Colon>semigroup_add, y] = [f x, f y]" by normalization
lemma "(map f [x \<Colon> 'a\<Colon>semigroup_add, y], w \<Colon> 'b\<Colon>finite) = ([f x, f y], w)" by normalization

end