Lapid–Mínguez conjecture on Jordan–Hölder constituents of parabolic induction

Let CiComp(di)C_i\in\operatorname{Comp}(\bm{d}_i) for i=1,,ki=1,\dots,k, let V=V1VkV=V^1\oplus\cdots\oplus V^k, and let CComp(V)C\in\operatorname{Comp}(V). Let π(C)\pi(C) denote the irreducible representation corresponding to CC, let JH\operatorname{JH} denote the set of Jordan–Hölder constituents, and let pip_i be the projection to the iith factor. Lapid–Mínguez's conjecture. The representation π(C)\pi(C) occurs as a subquotient of π(C1)××π(Ck)\pi(C_1)\times\cdots\times\pi(C_k) if and only if there is an irreducible component DD of C(C1××Ck)C\cap(C_1\times\cdots\times C_k) such that each restriction piDp_i|_D is dominant onto CiC_i. In particular, if all but at most one CiC_i are rigid, then

JH(π(C1)××π(Ck))={π(C)CC1Ck},\operatorname{JH}(\pi(C_1)\times\cdots\times\pi(C_k))=\{\pi(C)\mid C\supseteq C_1\oplus\cdots\oplus C_k\},

and if all CiC_i are rigid, then

JH(π(C1)××π(Ck))={π(C)x1xkC},\operatorname{JH}(\pi(C_1)\times\cdots\times\pi(C_k))=\{\pi(C)\mid x_1\oplus\cdots\oplus x_k\in C\},

where xix_i is a rigid element of CiC_i. The conjecture gives a geometric criterion for the representation-theoretic constituents of parabolic induction; the supplied text does not state a resolution.

Sources & referencesView supporting material

Primary source

Erez Lapid and Alberto Minguez, “A binary operation on irreducible components of Lusztig's nilpotent varieties II: applications and conjectures for representations of GL_n over a non-archimedean local field”, arXiv:2111.05162 (2022).

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