Hom-finiteness conjecture for tensor products in the category X(G)\mathscr{X}({\bf G})

From papers

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 abelian category of kG\Bbbk {\bf G}-modules defined by the stated condition on their T{\bf T}-weight spaces. 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}). Hom-finiteness conjecture. One has

dimkHomkG(MN,L)<.\dim_{\Bbbk}\operatorname{Hom}_{\Bbbk {\bf G}}(M\otimes N,L)<\infty.

Although tensor products of objects of X(G)\mathscr{X}({\bf G}) need not belong to the category and their simple quotients need not belong to it either, this conjecture predicts finite-dimensional Hom-spaces from such tensor products to every simple object. The source verifies it for the tensor products M(λ)JM(μ)\mathbb{M}(\lambda)_J\otimes\mathbb{M}(\mu), but gives no general resolution.

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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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