# HG changeset patch
# User paulson
# Date 966506521 -7200
# Node ID 47d39a31eb2f6bf0a7f3d9c61daee7e3d7705fcc
# Parent  a0d4d9de9893744b93616dbb914832b985f7ff9b
better rules for cancellation of common factors across comparisons

diff -r a0d4d9de9893 -r 47d39a31eb2f src/HOL/Divides.ML
--- a/src/HOL/Divides.ML	Thu Aug 17 12:01:09 2000 +0200
+++ b/src/HOL/Divides.ML	Thu Aug 17 12:02:01 2000 +0200
@@ -424,7 +424,6 @@
 Goalw [dvd_def]  "!!k::nat. [| (k*m) dvd (k*n); 0<k |] ==> m dvd n";
 by (etac exE 1);
 by (asm_full_simp_tac (simpset() addsimps mult_ac) 1);
-by (Blast_tac 1);
 qed "dvd_mult_cancel";
 
 Goalw [dvd_def] "[| i dvd m; j dvd n|] ==> (i*j) dvd (m*n :: nat)";
diff -r a0d4d9de9893 -r 47d39a31eb2f src/HOL/Nat.ML
--- a/src/HOL/Nat.ML	Thu Aug 17 12:01:09 2000 +0200
+++ b/src/HOL/Nat.ML	Thu Aug 17 12:02:01 2000 +0200
@@ -256,14 +256,6 @@
 qed "add_gr_0";
 AddIffs [add_gr_0];
 
-(* Could be generalized, eg to "k<n ==> m+(n-(Suc k)) = (m+n)-(Suc k)" *)
-Goal "!!m::nat. 0<n ==> m + (n-1) = (m+n)-1";
-by (case_tac "m" 1);
-by (ALLGOALS (asm_simp_tac (simpset() addsimps [diff_Suc, Suc_n_not_n]
-                                      addsplits [nat.split])));
-qed "add_pred";
-Addsimps [add_pred];
-
 Goal "!!m::nat. m + n = m ==> n = 0";
 by (dtac (add_0_right RS ssubst) 1);
 by (asm_full_simp_tac (simpset() addsimps [add_assoc]
@@ -673,54 +665,57 @@
 qed "mult_eq_1_iff";
 Addsimps [mult_eq_1_iff];
 
-Goal "!!m::nat. 0<k ==> (m*k < n*k) = (m<n)";
+Goal "!!m::nat. (m*k < n*k) = (0<k & m<n)";
 by (safe_tac (claset() addSIs [mult_less_mono1]));
-by (cut_facts_tac [less_linear] 1);
-by (blast_tac (claset() addIs [mult_less_mono1] addEs [less_asym]) 1);
+by (case_tac "k" 1);
+by Auto_tac;  
+by (full_simp_tac (simpset() delsimps [le_0_eq]
+			     addsimps [linorder_not_le RS sym]) 1);
+by (blast_tac (claset() addIs [mult_le_mono1]) 1); 
 qed "mult_less_cancel2";
 
-Goal "!!m::nat. 0<k ==> (k*m < k*n) = (m<n)";
-by (dtac mult_less_cancel2 1);
-by (etac subst 1);
-by (simp_tac (simpset() addsimps [mult_commute]) 1);
+Goal "!!m::nat. (k*m < k*n) = (0<k & m<n)";
+by (simp_tac (simpset() addsimps [mult_less_cancel2, 
+                                  inst "m" "k" mult_commute]) 1);
 qed "mult_less_cancel1";
 Addsimps [mult_less_cancel1, mult_less_cancel2];
 
-Goal "!!m::nat. 0<k ==> (m*k <= n*k) = (m<=n)";
-by (asm_full_simp_tac (simpset() addsimps [linorder_not_less RS sym]) 1);
+Goal "!!m::nat. (m*k <= n*k) = (0<k --> m<=n)";
+by (simp_tac (simpset() addsimps [linorder_not_less RS sym]) 1);
+by Auto_tac;  
 qed "mult_le_cancel2";
 
-Goal "!!m::nat. 0<k ==> (k*m <= k*n) = (m<=n)";
-by (asm_full_simp_tac (simpset() addsimps [linorder_not_less RS sym]) 1);
+Goal "!!m::nat. (k*m <= k*n) = (0<k --> m<=n)";
+by (simp_tac (simpset() addsimps [linorder_not_less RS sym]) 1);
+by Auto_tac;  
 qed "mult_le_cancel1";
 Addsimps [mult_le_cancel1, mult_le_cancel2];
 
-Goal "(Suc k * m < Suc k * n) = (m < n)";
-by (rtac mult_less_cancel1 1);
-by (Simp_tac 1);
-qed "Suc_mult_less_cancel1";
-
-Goalw [le_def] "(Suc k * m <= Suc k * n) = (m <= n)";
-by (simp_tac (simpset_of HOL.thy) 1);
-by (rtac Suc_mult_less_cancel1 1);
-qed "Suc_mult_le_cancel1";
-
-Goal "0 < (k::nat) ==> (m*k = n*k) = (m=n)";
+Goal "(m*k = n*k) = (m=n | (k = (0::nat)))";
 by (cut_facts_tac [less_linear] 1);
 by Safe_tac;
-by (assume_tac 2);
+by Auto_tac; 	
 by (ALLGOALS (dtac mult_less_mono1 THEN' assume_tac));
 by (ALLGOALS Asm_full_simp_tac);
 qed "mult_cancel2";
 
-Goal "0 < (k::nat) ==> (k*m = k*n) = (m=n)";
-by (dtac mult_cancel2 1);
-by (asm_full_simp_tac (simpset() addsimps [mult_commute]) 1);
+Goal "(k*m = k*n) = (m=n | (k = (0::nat)))";
+by (simp_tac (simpset() addsimps [mult_cancel2, inst "m" "k" mult_commute]) 1);
 qed "mult_cancel1";
 Addsimps [mult_cancel1, mult_cancel2];
 
+Goal "(Suc k * m < Suc k * n) = (m < n)";
+by (stac mult_less_cancel1 1);
+by (Simp_tac 1);
+qed "Suc_mult_less_cancel1";
+
+Goal "(Suc k * m <= Suc k * n) = (m <= n)";
+by (stac mult_le_cancel1 1);
+by (Simp_tac 1);
+qed "Suc_mult_le_cancel1";
+
 Goal "(Suc k * m = Suc k * n) = (m = n)";
-by (rtac mult_cancel1 1);
+by (stac mult_cancel1 1);
 by (Simp_tac 1);
 qed "Suc_mult_cancel1";
 
diff -r a0d4d9de9893 -r 47d39a31eb2f src/HOL/Power.ML
--- a/src/HOL/Power.ML	Thu Aug 17 12:01:09 2000 +0200
+++ b/src/HOL/Power.ML	Thu Aug 17 12:02:01 2000 +0200
@@ -34,7 +34,6 @@
 Goalw [dvd_def] "!!i::nat. m<=n ==> i^m dvd i^n";
 by (etac (not_less_iff_le RS iffD2 RS add_diff_inverse RS subst) 1);
 by (asm_simp_tac (simpset() addsimps [power_add]) 1);
-by (Blast_tac 1);
 qed "le_imp_power_dvd";
 
 Goal "!!i::nat. [| 0 < i; i^m < i^n |] ==> m < n";