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(************************************************************************)
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(* v * The Coq Proof Assistant / The Coq Development Team *)
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(* <O___,, * CNRS-Ecole Polytechnique-INRIA Futurs-Universite Paris Sud *)
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(* \VV/ **************************************************************)
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(* // * This file is distributed under the terms of the *)
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(* * GNU Lesser General Public License Version 2.1 *)
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(************************************************************************)
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(*i $Id: Zerob.v 9245 2006-10-17 12:53:34Z notin $ i*)
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Open Local Scope nat_scope.
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Definition zerob (n:nat) : bool :=
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Lemma zerob_true_intro : forall n:nat, n = 0 -> zerob n = true.
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destruct n; [ trivial with bool | inversion 1 ].
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Hint Resolve zerob_true_intro: bool.
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Lemma zerob_true_elim : forall n:nat, zerob n = true -> n = 0.
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destruct n; [ trivial with bool | inversion 1 ].
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Lemma zerob_false_intro : forall n:nat, n <> 0 -> zerob n = false.
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destruct n; [ destruct 1; auto with bool | trivial with bool ].
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Hint Resolve zerob_false_intro: bool.
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Lemma zerob_false_elim : forall n:nat, zerob n = false -> n <> 0.
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destruct n; [ inversion 1 | auto with bool ].
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