5078
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(* Title: HOL/Integ/Ring.ML
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ID: $Id$
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Author: Tobias Nipkow
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Copyright 1996 TU Muenchen
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Derives a few equational consequences about rings
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and defines cring_simpl, a simplification tactic for commutative rings.
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*)
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Goal "!!x::'a::cring. x*(y*z)=y*(x*z)";
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by (rtac trans 1);
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by (rtac times_commute 1);
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by (rtac trans 1);
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by (rtac times_assoc 1);
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by (simp_tac (HOL_basic_ss addsimps [times_commute]) 1);
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qed "times_commuteL";
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val times_cong = read_instantiate [("f1","op *")] (arg_cong RS cong);
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Goal "!!x::'a::ring. zero*x = zero";
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by (rtac trans 1);
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by (rtac right_inv 2);
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by (rtac trans 1);
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by (rtac plus_cong 2);
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by (rtac refl 3);
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by (rtac trans 2);
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by (rtac times_cong 3);
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by (rtac zeroL 3);
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by (rtac refl 3);
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by (rtac (distribR RS sym) 2);
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by (rtac trans 1);
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by (rtac (plus_assoc RS sym) 2);
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by (rtac trans 1);
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by (rtac plus_cong 2);
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by (rtac refl 2);
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by (rtac (right_inv RS sym) 2);
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by (rtac (zeroR RS sym) 1);
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qed "mult_zeroL";
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Goal "!!x::'a::ring. x*zero = zero";
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by (rtac trans 1);
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by (rtac right_inv 2);
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by (rtac trans 1);
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by (rtac plus_cong 2);
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by (rtac refl 3);
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by (rtac trans 2);
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by (rtac times_cong 3);
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by (rtac zeroL 4);
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by (rtac refl 3);
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by (rtac (distribL RS sym) 2);
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by (rtac trans 1);
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by (rtac (plus_assoc RS sym) 2);
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by (rtac trans 1);
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by (rtac plus_cong 2);
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by (rtac refl 2);
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by (rtac (right_inv RS sym) 2);
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by (rtac (zeroR RS sym) 1);
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qed "mult_zeroR";
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Goal "!!x::'a::ring. (zero-x)*y = zero-(x*y)";
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by (rtac trans 1);
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by (rtac zeroL 2);
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by (rtac trans 1);
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by (rtac plus_cong 2);
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by (rtac refl 3);
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by (rtac mult_zeroL 2);
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by (rtac trans 1);
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by (rtac plus_cong 2);
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by (rtac refl 3);
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by (rtac times_cong 2);
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by (rtac left_inv 2);
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by (rtac refl 2);
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by (rtac trans 1);
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by (rtac plus_cong 2);
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by (rtac refl 3);
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by (rtac (distribR RS sym) 2);
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by (rtac trans 1);
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by (rtac (plus_assoc RS sym) 2);
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by (rtac trans 1);
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by (rtac plus_cong 2);
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by (rtac refl 2);
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by (rtac (right_inv RS sym) 2);
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by (rtac (zeroR RS sym) 1);
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qed "mult_invL";
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Goal "!!x::'a::ring. x*(zero-y) = zero-(x*y)";
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by (rtac trans 1);
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by (rtac zeroL 2);
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by (rtac trans 1);
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by (rtac plus_cong 2);
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by (rtac refl 3);
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by (rtac mult_zeroR 2);
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by (rtac trans 1);
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by (rtac plus_cong 2);
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by (rtac refl 3);
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by (rtac times_cong 2);
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by (rtac refl 2);
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by (rtac left_inv 2);
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by (rtac trans 1);
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by (rtac plus_cong 2);
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by (rtac refl 3);
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by (rtac (distribL RS sym) 2);
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by (rtac trans 1);
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by (rtac (plus_assoc RS sym) 2);
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by (rtac trans 1);
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by (rtac plus_cong 2);
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by (rtac refl 2);
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by (rtac (right_inv RS sym) 2);
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by (rtac (zeroR RS sym) 1);
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qed "mult_invR";
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Goal "x*(y-z) = (x*y - x*z::'a::ring)";
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by (mk_group1_tac 1);
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by (simp_tac (HOL_basic_ss addsimps [distribL,mult_invR]) 1);
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qed "minus_distribL";
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Goal "(x-y)*z = (x*z - y*z::'a::ring)";
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by (mk_group1_tac 1);
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by (simp_tac (HOL_basic_ss addsimps [distribR,mult_invL]) 1);
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qed "minus_distribR";
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val cring_simps = [times_assoc,times_commute,times_commuteL,
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distribL,distribR,minus_distribL,minus_distribR]
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@ agroup2_simps;
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val cring_tac =
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let val ss = HOL_basic_ss addsimps cring_simps
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in simp_tac ss end;
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(*** The order [minus_plusL3,minus_plusL2] is important because minus_plusL3
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MUST be tried first
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val cring_simp =
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let val phase1 = simpset() addsimps
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[plus_minusL,minus_plusR,minus_minusR,plus_minusR]
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val phase2 = HOL_ss addsimps [minus_plusL3,minus_plusL2,
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zeroL,zeroR,mult_zeroL,mult_zeroR]
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in simp_tac phase1 THEN' simp_tac phase2 end;
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***)
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