{ "id": "1709.10198", "version": "v1", "published": "2017-09-28T23:29:28.000Z", "updated": "2017-09-28T23:29:28.000Z", "title": "Balanced complexes and effective divisors on $\\overline{M}_{0,n}$", "authors": [ "José Luis González", "Elijah Gunther", "Olivia Zhang" ], "comment": "10 pages, 8 figures", "categories": [ "math.AG", "math.CO" ], "abstract": "Doran, Jensen and Giansiracusa showed a bijection between homogeneous elements in the Cox ring of $\\overline{M}_{0,n}$ not divisible by any exceptional divisor section, and weighted pure-dimensional simplicial complexes satisfying a zero-tension condition. Motivated by the study of the monoid of effective divisors, the pseudoeffective cone and the Cox ring of $\\overline{M}_{0,n}$, we point out a simplification of the zero-tension condition and study the space of balanced complexes. We give examples of irreducible elements in the monoid of effective divisors of $\\overline{M}_{0,n}$ for large $n$. In the case of $\\overline{M}_{0,7}$, we classify all such irreducible elements arising from nonsingular complexes and give an example of how irreducibility can be shown in the singular case.", "revisions": [ { "version": "v1", "updated": "2017-09-28T23:29:28.000Z" } ], "analyses": { "subjects": [ "14C20", "14H10", "05E45" ], "keywords": [ "effective divisors", "balanced complexes", "zero-tension condition", "exceptional divisor section", "irreducible elements" ], "note": { "typesetting": "TeX", "pages": 10, "language": "en", "license": "arXiv", "status": "editable" } } }