Weight-support vanishing conjecture for tensor products in the category X(G)\mathscr{X}({\bf G})

Let G{\bf G} be the group under consideration, let k\Bbbk be the coefficient field, and let X(G)\mathscr{X}({\bf G}) be the stated category of kG\Bbbk {\bf G}-modules. For a T{\bf T}-module VV, write

XT(V)={θT^Vθ0}\mathbb{X}_{\bf T}(V)=\{\theta\in\widehat{\bf T}\mid V_\theta\ne0\}

for its set of T{\bf T}-weights. Let M,NX(G)M,N\in\mathscr{X}({\bf G}), and let LL be a simple object of X(G)\mathscr{X}({\bf G}). Weight-support vanishing conjecture. If

XT(L)XT(MN)=,\mathbb{X}_{\bf T}(L)\cap\mathbb{X}_{\bf T}(M\otimes N)=\varnothing,

then

HomkG(MN,L)=0.\operatorname{Hom}_{\Bbbk {\bf G}}(M\otimes N,L)=0.

This conjecture asserts that a simple target cannot receive a nonzero morphism from the tensor product when their T{\bf T}-weight supports are disjoint. The source verifies it for M(λ)JM(μ)\mathbb{M}(\lambda)_J\otimes\mathbb{M}(\mu), but does not resolve it for arbitrary objects of X(G)\mathscr{X}({\bf G}).

Sources & referencesView supporting material

Primary source

Junbin Dong, “Some conjectures on the quotients of the tensor products in the category X”, arXiv:2508.00488 (2026).

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