Regularity of powers of bipartite graphs

被引:0
作者
A. V. Jayanthan
N. Narayanan
S. Selvaraja
机构
[1] Indian Institute of Technology Madras,Department of Mathematics
来源
Journal of Algebraic Combinatorics | 2018年 / 47卷
关键词
Bipartite graphs; Castelnuovo–Mumford regularity; Induced matching number; Co-chordal cover number; Edge ideal;
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中图分类号
学科分类号
摘要
Let G be a finite simple graph and I(G) denote the corresponding edge ideal. For all s≥1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$s \ge 1$$\end{document}, we obtain upper bounds for reg(I(G)s)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text {reg}}(I(G)^s)$$\end{document} for bipartite graphs. We then compare the properties of G and G′\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$G'$$\end{document}, where G′\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$G'$$\end{document} is the graph associated with the polarization of the ideal (I(G)s+1:e1⋯es)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$(I(G)^{s+1} : e_1\cdots e_s)$$\end{document}, where e1,⋯,es\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$e_1,\cdots , e_s$$\end{document} are edges of G. Using these results, we explicitly compute reg(I(G)s)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text {reg}}(I(G)^s)$$\end{document} for several subclasses of bipartite graphs.
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页码:17 / 38
页数:21
相关论文
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