add a left and right tactic for classical logic

git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/trunk@7234 85f007b7-540e-0410-9357-904b9bb8a0f7

1 files changed, 12 insertions, 1 deletions

diff --git a/theories/Logic/Classical_Prop.v b/theories/Logic/Classical_Prop.v
index fa509a3c0..1df6a354b 100755
--- a/theories/Logic/Classical_Prop.v
+++ b/theories/Logic/Classical_Prop.v
@@ -82,4 +82,15 @@ simple induction 2; auto.
 Qed.
 
 Lemma proof_irrelevance : forall (P:Prop) (p1 p2:P), p1 = p2.
-Proof proof_irrelevance_cci classic.
\ No newline at end of file
+Proof proof_irrelevance_cci classic.
+
+(* classical_left  transforms |- A \/ B into ~B |- A *)
+(* classical_right transforms |- A \/ B into ~A |- B *)
+
+Ltac classical_right :=  match goal with 
+ | _:_ |-?X1 \/ _ => (elim (classic X1);intro;[left;trivial|right])
+end.
+
+Ltac classical_left := match goal with 
+| _:_ |- _ \/?X1 => (elim (classic X1);intro;[right;trivial|left])
+end.
\ No newline at end of file