changeset 1920 | df683ce7aad8 |
parent 1882 | 67f49e8c4355 |
child 1937 | e59ff0eb1e91 |
--- a/src/HOL/Set.ML Mon Aug 19 11:49:31 1996 +0200 +++ b/src/HOL/Set.ML Mon Aug 19 11:51:39 1996 +0200 @@ -115,6 +115,9 @@ qed_goal "rev_subsetD" Set.thy "[| c:A; A <= B |] ==> c:B" (fn prems=> [ (REPEAT (resolve_tac (prems@[subsetD]) 1)) ]); +(*Converts A<=B to x:A ==> x:B*) +fun impOfSubs th = th RSN (2, rev_subsetD); + qed_goal "contra_subsetD" Set.thy "!!c. [| A <= B; c ~: B |] ==> c ~: A" (fn prems=> [ (REPEAT (eresolve_tac [asm_rl, contrapos, subsetD] 1)) ]);