{ "id": "0902.1072", "version": "v3", "published": "2009-02-06T11:52:44.000Z", "updated": "2009-11-26T09:06:49.000Z", "title": "Combinatorics and Genus of Tropical Intersections and Ehrhart Theory", "authors": [ "Reinhard Steffens", "Thorsten Theobald" ], "comment": "Small revisions", "categories": [ "math.CO", "math.AG" ], "abstract": "Let $g_1, ..., g_k$ be tropical polynomials in $n$ variables with Newton polytopes $P_1, ..., P_k$. We study combinatorial questions on the intersection of the tropical hypersurfaces defined by $g_1, ..., g_k$, such as the $f$-vector, the number of unbounded faces and (in case of a curve) the genus. Our point of departure is Vigeland's work who considered the special case $k=n-1$ and where all Newton polytopes are standard simplices. We generalize these results to arbitrary $k$ and arbitrary Newton polytopes $P_1, ..., P_k$. This provides new formulas for the number of faces and the genus in terms of mixed volumes. By establishing some aspects of a mixed version of Ehrhart theory we show that the genus of a tropical intersection curve equals the genus of a toric intersection curve corresponding to the same Newton polytopes.", "revisions": [ { "version": "v3", "updated": "2009-11-26T09:06:49.000Z" } ], "analyses": { "subjects": [ "52B70", "52C45", "14M25", "52B20" ], "keywords": [ "ehrhart theory", "combinatorics", "tropical intersection curve equals", "arbitrary newton polytopes", "study combinatorial questions" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2009arXiv0902.1072S" } } }