Created
December 20, 2014 12:02
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Require Import ssreflect ssrbool ssrnat. | |
(* Software Foundation 練習問題: ★★, recommended (basic_induction) *) | |
Lemma ゼロを掛けるとゼロになる : forall (n:nat), n*0 = 0. | |
Proof. | |
move=> n. | |
induction n as [| m]. | |
trivial. (* 0*0 == 0 *) | |
rewrite mulSnr. (* m.+1 * 0 ~~~> m * 0 + 0 *) | |
rewrite -> IHm. (* apply IHm : m * 0 == 0 *) | |
reflexivity. | |
Qed. |
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