{ "id": "2205.03796", "version": "v1", "published": "2022-05-08T06:36:37.000Z", "updated": "2022-05-08T06:36:37.000Z", "title": "Chain enumeration, partition lattices and polynomials with only real roots", "authors": [ "Christos A. Athanasiadis", "Katerina Kalampogia-Evangelinou" ], "comment": "19 pages, zero figures", "categories": [ "math.CO" ], "abstract": "The coefficients of the chain polynomial of a finite poset enumerate chains in the poset by their number of elements. The chain polynomials of the partition lattices and their standard type $B$ analogues are shown to have only real roots. The real-rootedness of the chain polynomial is conjectured for all geometric lattices and is shown to be preserved by the pyramid and the prism operations on Cohen--Macaulay posets. As a result, new families of convex polytopes whose face lattices have real-rooted chain polynomials are presented. An application to the face enumeration of the second barycentric subdivision of the boundary complex of the simplex is also included.", "revisions": [ { "version": "v1", "updated": "2022-05-08T06:36:37.000Z" } ], "analyses": { "subjects": [ "05A05", "05A18", "05E45", "06A07", "26C10" ], "keywords": [ "partition lattices", "real roots", "chain polynomial", "chain enumeration", "finite poset enumerate chains" ], "note": { "typesetting": "TeX", "pages": 19, "language": "en", "license": "arXiv", "status": "editable" } } }