Interval-completion bound for the defining ideal of a numerical semigroup tangent cone

Let H=a1,,arH=\langle a_1,\dots,a_r\rangle be a numerical semigroup, and let H~\widetilde H be its interval completion, the numerical semigroup generated by all integers in the interval [a1,ar][a_1,a_r]. Let IHI_H^* and IH~I_{\widetilde H}^* denote the defining ideals of the tangent cones of HH and H~\widetilde H, respectively. Interval-completion bound conjecture. For every numerical semigroup HH,

μ(IH)μ(IH~).\mu(I_H^*)\leq\mu(I_{\widetilde H}^*).

The conjecture compares the number of minimal generators of the tangent-cone defining ideal with that of the interval completion, whose generators fill the interval between the smallest and largest generators of HH. The source gives no proof or evidence of resolution, so the status remains open.

Sources & referencesView supporting material

Primary source

Jürgen Herzog and Dumitru I. Stamate, “On the defining equations of the tangent cone of a numerical semigroup ring”, arXiv:1308.4644 (2014).

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