{ "id": "1402.3100", "version": "v1", "published": "2014-02-13T11:57:48.000Z", "updated": "2014-02-13T11:57:48.000Z", "title": "On Syzygies, degree, and geometric properties of projective schemes with property $\\textbf{N}_{3,p}$", "authors": [ "Jeaman Ahn", "Sijong Kwak" ], "comment": "14 pages", "categories": [ "math.AG", "math.AC" ], "abstract": "For an algebraic set $X$ (union of varieties) embedded in projective space, we say that $X$ satisfies property $\\textbf{N}_{d,p}$, $(d\\ge 2)$ if the $i$-th syzygies of the homogeneous coordinate ring are generated by elements of degree $< d+i$ for $0\\le i\\le p$ (see \\cite{EGHP2} for details). Much attention has been paid to linear syzygies of quadratic schemes $(d=2)$ and their geometric interpretations (cf. \\cite{AK},\\cite{EGHP1},\\cite{HK},\\cite{GL2},\\cite{KP}). However, not very much is actually known about the case satisfying property $\\textbf{N}_{3,p}$. In this paper, we give a sharp upper bound on the maximal length of a zero-dimensional linear section of $X$ in terms of graded Betti numbers (Theorem 1.2 (a)) when $X$ satisfies property $\\textbf{N}_{3,p}$. In particular, if $p$ is the codimension $e$ of $X$ then the degree of $X$ is less than or equal to $\\binom{e+2}{2}$, and equality holds if and only if $X$ is arithmetically Cohen-Maucalay with $3$-linear resolution (Theorem 1.2 (b)). This is a generalization of the results of Eisenbud et al. (\\cite{EGHP1,EGHP2}) to the case of $\\textbf{N}_{3,p}$, $(p\\leq e)$.", "revisions": [ { "version": "v1", "updated": "2014-02-13T11:57:48.000Z" } ], "analyses": { "subjects": [ "14N05", "13D02" ], "keywords": [ "geometric properties", "projective schemes", "satisfies property", "sharp upper bound", "zero-dimensional linear section" ], "note": { "typesetting": "TeX", "pages": 14, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2014arXiv1402.3100A" } } }