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| -rw-r--r-- | CHANGELOG_UNRELEASED.md | 1 | ||||
| -rw-r--r-- | mathcomp/fingroup/perm.v | 3 |
2 files changed, 4 insertions, 0 deletions
diff --git a/CHANGELOG_UNRELEASED.md b/CHANGELOG_UNRELEASED.md index d8bd318..86c920b 100644 --- a/CHANGELOG_UNRELEASED.md +++ b/CHANGELOG_UNRELEASED.md @@ -250,6 +250,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/). Its name will become `prodrMn` in the next release when this name will become available (cf. Renamed section) - in `polydiv.v`, new lemma `dvdpNl`. +- in `perm.v` new lemma `permS01`. ### Changed diff --git a/mathcomp/fingroup/perm.v b/mathcomp/fingroup/perm.v index ebd4230..5775e34 100644 --- a/mathcomp/fingroup/perm.v +++ b/mathcomp/fingroup/perm.v @@ -640,6 +640,9 @@ Proof. by move=> g; apply/permP; case. Qed. Lemma permS1 : all_equal_to (1 : 'S_1). Proof. by move=> g; apply/permP => i; rewrite !ord1. Qed. +Lemma permS01 n : n <= 1 -> all_equal_to (1 : 'S_n). +Proof. by case: n => [|[|]//=] _ g; rewrite (permS0, permS1). Qed. + Section CastSn. Definition cast_perm m n (eq_mn : m = n) (s : 'S_m) := |