This paper is the third in a series of manuscripts that examine the combinatorics of the Kunz polyhedron $$P_m$$, whose positive integer points are in bijection with numerical semigroups (cofinite subsemigroups of $$\mathbb Z_{\ge 0}$$) whose smallest positive element is $$m$$. The faces of $$P_m$$ are indexed by a family of finite posets (called Kunz posets) obtained from the divisibility posets of the numerical semigroups lying on a given face. In this paper, we characterize to what extent the minimal presentation of a numerical semigroup can be recovered from its Kunz poset. In doing so, we prove that all numerical semigroups lying on the interior of a given face of $$P_m$$ have identical minimal presentation cardinality, and we provide a combinatorial method of obtaining the dimension of a face from its corresponding Kunz poset.
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Numerical semigroups, polyhedra, and posets II: locating certain families of semigroups
Abstract Several recent papers have examined a rational polyhedronPmwhose integer points are in bijection with the numerical semigroups (cofinite, additively closed subsets of the non-negative integers) containingm. A combinatorial description of the faces ofPmwas recently introduced, one that can be obtained from the divisibility posets of the numerical semigroups a given face contains. In this paper, we study the faces ofPmcontaining arithmetical numerical semigroups and those containing certain glued numerical semigroups, as an initial step towards better understanding the full face structure ofPm. In most cases, such faces only contain semigroups from these families, yielding a tight connection to the geometry ofPm.
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- Award ID(s):
- 1851542
- PAR ID:
- 10503511
- Publisher / Repository:
- De Gruyter
- Date Published:
- Journal Name:
- Advances in Geometry
- Volume:
- 22
- Issue:
- 1
- ISSN:
- 1615-715X
- Page Range / eLocation ID:
- 33 to 48
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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