diff options
| author | Cyril Cohen | 2019-11-18 18:22:20 +0100 |
|---|---|---|
| committer | Cyril Cohen | 2019-11-18 18:22:20 +0100 |
| commit | d27936801b2997af16814e2879c8bdf6f4eb7bcc (patch) | |
| tree | 3bc4441094d6abc226e1bb72ba6c7c20604fe066 | |
| parent | 64265294b519d7cd9f982edf24991c7f210933a9 (diff) | |
Adding `inj_compr` lemma in ssrfun.
| -rw-r--r-- | plugins/ssr/ssrfun.v | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/plugins/ssr/ssrfun.v b/plugins/ssr/ssrfun.v index b8affba541..dd847169b9 100644 --- a/plugins/ssr/ssrfun.v +++ b/plugins/ssr/ssrfun.v @@ -675,6 +675,9 @@ Proof. by move=> fK injf' x; apply: injf'. Qed. Lemma inj_comp : injective f -> injective h -> injective (f \o h). Proof. by move=> injf injh x y /injf; apply: injh. Qed. +Lemma inj_compr : injective (f \o h) -> injective h. +Proof. by move=> injfh x y /(congr1 f) /injfh. Qed. + Lemma can_comp f' h' : cancel f f' -> cancel h h' -> cancel (f \o h) (h' \o f'). Proof. by move=> fK hK x; rewrite /= fK hK. Qed. |