{ "id": "0704.3994", "version": "v1", "published": "2007-04-30T18:43:14.000Z", "updated": "2007-04-30T18:43:14.000Z", "title": "Covers of Elliptic Curves and the Lower Bound for Slopes of Effective Divisors on $\\bar{\\mathcal M}_{g}$", "authors": [ "Dawei Chen" ], "comment": "41 pages, 19 figures", "categories": [ "math.AG", "math.CO", "math.GT" ], "abstract": "Consider genus $g$ curves that admit degree $d$ covers to elliptic curves only branched at one point with a fixed ramification type. The locus of such covers forms a one parameter family $Y$ that naturally maps into the moduli space of stable genus $g$ curves $\\bar{\\mathcal M}_{g}$. We study the geometry of $Y$, and produce a combinatorial method by which to investigate its slope, irreducible components, genus and orbifold points. As a by-product of our approach, we find some equalities from classical number theory. Moreover, a correspondence between our method and the viewpoint of square-tiled surfaces is established. We also use our results to study the lower bound for slopes of effective divisors on $\\bar{\\mathcal M}_{g}$.", "revisions": [ { "version": "v1", "updated": "2007-04-30T18:43:14.000Z" } ], "analyses": { "subjects": [ "14H10", "14H30", "05A15", "05E15" ], "keywords": [ "lower bound", "elliptic curves", "effective divisors", "admit degree", "classical number theory" ], "note": { "typesetting": "TeX", "pages": 41, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2007arXiv0704.3994C" } } }