Title
Simple Matroids with Bounded Cocircuit Size
Abstract
We examine the specialization to simple matroids of certain problems in extremal matroid theory that are concerned with bounded cocircuit size. Assume that each cocircuit of a simple matroid M has at most d elements. We show that if M has rank 3, then M has at most d + ⌊√d⌋ + 1 points, and we classify the rank-3 simple matroids M that have exactly d + ⌊√d⌋ points. We show that if M is a connected matroid of rank 4 and d is q3 with q 1, then M has at most q3 + q2 + q + 1 points; this upper bound is strict unless q is a prime power, in which case the only such matroid with exactly q3 + q2 + q + 1 points is the projective geometry PG(3, q). We also show that if d is q4 for a positive integer q and if M has rank 5 and is vertically 5-connected, then M has at most q4 + q3 + q2 + q + 1 points; this upper bound is strict unless q is a prime power, in which case PG(4, q) is the only such matroid that attains this bound.
Year
DOI
Venue
2000
10.1017/S0963548300004429
Combinatorics, Probability & Computing
Keywords
Field
DocType
case pg,bounded cocircuit size,connected matroid,positive integer q,simple matroids,extremal matroid theory,prime power,simple matroid,certain problem,rank-3 simple matroids m
Integer,Matroid,Discrete mathematics,Combinatorics,Projective geometry,Upper and lower bounds,Matroid partitioning,Graphic matroid,Prime power,Mathematics,Bounded function
Journal
Volume
Issue
ISSN
9
5
0963-5483
Citations 
PageRank 
References 
0
0.34
1
Authors
2
Name
Order
Citations
PageRank
Joseph E. Bonin15316.74
Talmage James Reid24812.18