Aharoni and Berger conjectured that every collection of n matchings of size n+1 in a bipartite graph contains a rainbow matching of size n. This conjecture is related to several old conjectures of Ryser, Brualdi, and Stein about transversals in Latin squares. There have been many recent partial results about the Aharoni-Berger Conjecture. The conjecture is known to hold when the matchings are m...

The permanent-determinant method and its generalization, the HafnianPfaffian method, are methods to enumerate perfect matchings of plane graphs that were discovered by P. W. Kasteleyn. We present several new techniques and arguments related to the permanent-determinant with consequences in enumerative combinatorics. Here are some of the results that follow from these techniques: 1. If a biparti...

The anti-Kekul\'{e} number of a connected graph $G$ is the smallest edges whose deletion results in subgraph having no Kekul\'{e} structures (perfect matchings). As common generalization (conditional) matching preclusion and $G$, we introduce $s$-restricted as without perfect matchings such that each component has at least $s+1$ vertices. In this paper, first show conditional problem are NP-com...

Given a graph G = (V, E) and a spanning subgraph H of G (the backbone of G), a backbone coloring for G and H is a proper vertex coloring V → {1, 2, . . .} of G in which the colors assigned to adjacent vertices in H differ by at least two. In a recent paper, backbone colorings were introduced and studied in cases were the backbone is either a spanning tree or a spanning path. Here we study the c...

This paper considers some classes of graphs which are easily seen to have many perfect matchings. Such graphs can be considered robust with respect to the property of having a perfect matching if under vertex deletions (with some mild restrictions), the resulting subgraph continues to have a perfect matching. It is clear that you can destroy the property of having a perfect matching by deleting...

When we think about markets creating opportunities for interaction between buyers and sellers, there is an implicit network encoding the access between buyers and sellers. In fact, there are several ways to use networks to model buyer-seller interaction, and here we discuss some of them. First, consider the case in which not all buyers have access to all sellers. There could be several reasons ...

We show that every cubic bridgeless graph with n vertices has at least 3n/4 − 10 perfect matchings. This is the first bound that differs by more than a constant from the maximal dimension of the perfect matching polytope.

Approximately Counting Perfect And General Matchings in Bipartite and General Graphs

In this paper, we propose an algorithm for enumerating all the perfect matchings included in a given bipartite graph G = (V,E). The algorithm is improved by the approach which we proposed at ISAAC98. Our algorithm takes O(log |V |) time per perfect matching while the current fastest algorithm takes O(|V |) time per perfect matching. Keyword: enumeration, enumerating algorithm, perfect matching.