The sufficient condition for finite generation of simple irrational polyhedral cones

Let CRnC\subset\mathbb{R}^n be a simple polyhedral cone with extreme rays [u1],,[un][u_1],\dots,[u_n], where [u1],,[uk][u_1],\dots,[u_k] are rational.

Finite-generation conjecture. The cone CC is (R,G)(R,G)-finitely generated if and only if there exists AQn×nA\in\mathbb{Q}^{n\times n} and λ1,,λnR>0\lambda_1,\dots,\lambda_n\in\mathbb{R}_{>0} such that Aui=λiuiAu_i=\lambda_i u_i for i=1,,ni=1,\dots,n and λk+1,,λn\lambda_{k+1},\dots,\lambda_n are distinct.

The sufficient condition is known by Theorem; the conjecture asserts that it is also necessary. The surrounding discussion notes that the necessity is established in dimension three, while higher-dimensional examples with repeated eigenvalues show that the general question remains open.

Sources & referencesView supporting material

Primary source

Grigoriy Blekherman, Jesús A. De Loera, Luze Xu and Shixuan Zhang, “Semigroups of Integer Points in Convex Cones”, arXiv:2504.15537 (2025).

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