proposition: Lemma yamtab_shift_included innev maxi sh y : included innev outev -> forall res shape, (res, shape) \in yamtab_shift innev maxi sh y -> included shape outev.
proof: Proof. Proof using . elim: sh innev y => [| sh IHsh] /= innev y Hincl res shres. by rewrite mem_seq1 => /eqP[_ ->]. move/flatten_mapP => [[rec shrec]] /(IHsh innev y Hincl) {IHsh} Hrec. move/mapP => [i Hi [_ ->]]. exact: (one_letter_included Hrec Hi). Qed.
imports: mathcomp(all_ssreflect) mathcomp(ssralg) mathcomp(mpoly) tools combclass partition Yamanouchi ordtype tableau skewtab Schur_mpoly freeSchur therule