Case 4 (§15.10) for Mix (Lambda, Pi). #
This file factors the Case-4 obligation for Mix (Lambda, Pi) into:
exists_mutation_le_fifteen_ten_LP_caseA: the sorried "Case A" core, where additionally(sigma X 1).1 < (sigma Y 1).1;exists_mutation_le_fifteen_ten_LP: the full Case 4, dispatching to Case A on the<branch and to its sign-dual (Case B) on the¬<branch.
This mirrors Pi.exists_mutation_le_fifteen_ten in YoungDiagram/Theorem6/Pi.lean.
The Case-B branch is fully proved via the negation lemmas; the Case-A core is
delegated to MixLambdaPi.exists_mutation_le_caseA / MixPiLambda.exists_mutation_le_caseA
(files MixLambdaPi/CaseA.lean, MixPiLambda/CaseA.lean), which dispatch on the
minimal-rank gene's polarization (§16 Branch A / Branch B); the two branch leaves
per variety are the remaining sorrys.
Case A of §15.10 for Mix (Lambda, Pi): the additional hypothesis is
(sigma X 1).1 < (sigma Y 1).1. This is the sorried core.
Case 4 (§15.10) for Mix (Lambda, Pi). Dispatches to Case A on the branch
(sigma X 1).1 < (sigma Y 1).1; on the other branch builds the sign-dual and
reduces to Case A applied to -X, -Y.
Case A of §15.10 for Mix (Pi, Lambda): the additional hypothesis is
(sigma X 1).1 < (sigma Y 1).1. This is the sorried core.
Case 4 (§15.10) for Mix (Pi, Lambda). Dispatches to Case A on the branch
(sigma X 1).1 < (sigma Y 1).1; on the other branch builds the sign-dual and
reduces to Case A applied to -X, -Y.