The sufficient condition for finite generation of simple irrational polyhedral cones

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Let C⊂RnC\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 A∈Qn×nA\in\mathbb{Q}^{n\times n} and λ1,…,λn∈R>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.

References

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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