# HG changeset patch # User oheimb # Date 941184631 -7200 # Node ID 7a20317850ab18363e83ba0623f7913c2f89d964 # Parent 964b65b4e4331b29d4c219fbd39560f5d1b23a4e improved singleton_insert_inj_eq diff -r 964b65b4e433 -r 7a20317850ab src/HOL/Set.ML --- a/src/HOL/Set.ML Thu Oct 28 19:57:34 1999 +0200 +++ b/src/HOL/Set.ML Fri Oct 29 10:10:31 1999 +0200 @@ -500,11 +500,15 @@ AddSDs [singleton_inject]; AddSEs [singletonE]; -Goal "{b} = insert a A = (a = b & A <= {a})"; +Goal "{b} = insert a A = (a = b & A <= {b})"; by (safe_tac (claset() addSEs [equalityE])); by (ALLGOALS Blast_tac); qed "singleton_insert_inj_eq"; +Goal "(insert a A = {b} ) = (a = b & A <= {b})"; +by (rtac (singleton_insert_inj_eq RS (eq_sym_conv RS trans)) 1); +qed "singleton_insert_inj_eq'"; + Goal "A <= {x} ==> A={} | A = {x}"; by (Fast_tac 1); qed "subset_singletonD";