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Diffstat (limited to 'theories/Logic/Decidable.v')
| -rw-r--r-- | theories/Logic/Decidable.v | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/theories/Logic/Decidable.v b/theories/Logic/Decidable.v index 6f793ce2f..6129128de 100644 --- a/theories/Logic/Decidable.v +++ b/theories/Logic/Decidable.v @@ -80,6 +80,13 @@ Proof. unfold decidable; tauto. Qed. +Theorem not_iff : + forall A B:Prop, decidable A -> decidable B -> + ~ (A <-> B) -> (A /\ ~ B) \/ (~ A /\ B). +Proof. +unfold decidable; tauto. +Qed. + (** Results formulated with iff, used in FSetDecide. Negation are expanded since it is unclear whether setoid rewrite will always perform conversion. *) |