Title
Ehrhart clutters: Regularity and Max-Flow Min-Cut
Abstract
If C is a clutter with n vertices and q edges whose clutter matrix has column vectors A = {v(1),...,v(q)), we call C and Ehrhart clutter if {(v(1),1),..., (v(q),1)} subset of {0, 1}(n+1) is a Hilbert basis. Letting A(P) be the Ehrhart ring of P = conv(A), we are able to show that if C is a uniform unmixed MFMC clutter, then C is an Ehrhart clutter and in this case we provide sharp upper bounds on the Castelnuovo-Mumford regularity and the a-invariant of A(P). Motivated by the Conforti-Cornuejols conjecture on packing problems, we conjecture that if C is both ideal and the clique clutter of a perfect graph, then C has the MFMC property. We prove this conjecture for Meyniel graphs by showing that the clique clutters of Meyniel graphs are Ehrhart clutters. In much the same spirit, we provide a simple proof of our conjecture when C is a uniform clique clutter of a perfect graph. We close with a generalization of Ehrhart clutters as it related to total dual integrality.
Year
Venue
Keywords
2010
ELECTRONIC JOURNAL OF COMBINATORICS
perfect graphs,hilbert bases.,a-invariant,clutters,regularity,max-flow min-cut,edge ideal,. ehrhart ring,perfect graph
Field
DocType
Volume
Perfect graph,Hilbert basis,Discrete mathematics,Combinatorics,Clique,Vertex (geometry),Matrix (mathematics),Max-flow min-cut theorem,Total dual integrality,Conjecture,Mathematics
Journal
17.0
Issue
ISSN
Citations 
1.0
1077-8926
2
PageRank 
References 
Authors
0.58
7
3
Name
Order
Citations
PageRank
Jose Mart ´ õnez-Bernal120.58
Edwin O'Shea230.94
Rafael H. Villarreal37515.69