Title
Biased graphs. II.: The three matroids
Abstract
A biased graph Ω consists of a graph Γ and a class B of circles (simple, closed paths) in Γ, called balanced circles, such that no theta subgraph contains exactly two balanced circles. The bias matroid G(Ω) is a finitary matroid on the edge set E of Ω whose circuits are the balanced circles and the minimal connected edge sets of cyclomatic number two containing no balanced circle. We prove that these circuits define a matroid and we establish cryptomorphic definitions and other properties. Another finitary matroid on E , the lift matroid L(Ω) , and its one-point extension the complete lift matroid L 0 (Ω) , are obtained from the abstract matroid lift construction applied to the graphic matroid G ( Γ ) and the class B . The circuits of L(Ω) are the balanced circles and the minimal edge sets of cyclomatic number two (not necessarily connected) containing no balanced circle. We develop cryptomorphisms and other properties of L 0 (Ω) and L(Ω) . There is no completely general construction rule, besides the bias and lift constructions, which assigns to each biased graph a matroid intermediate (in the sense of independent sets) between G and L and which respects subgraphs. G(Ω) has an infinitary analog for infinite graphs generalizing Klee's infinitary bicircular matroid and the Bean-Higgs infinitary graphic matroid. Whether L(Ω) has an infinitary analog is unclear.
Year
DOI
Venue
1991
10.1016/0095-8956(91)90005-5
J. Comb. Theory, Ser. B
Field
DocType
Volume
Matroid,Bicircular matroid,Discrete mathematics,Combinatorics,k-edge-connected graph,Oriented matroid,Matroid partitioning,Biased graph,Graphic matroid,Weighted matroid,Mathematics
Journal
51
Issue
ISSN
Citations 
1
Journal of Combinatorial Theory, Series B
43
PageRank 
References 
Authors
2.87
7
1
Name
Order
Citations
PageRank
T. Zaslavsky129756.67