Elementary decomposition of soliton automata

Soliton automata are the mathematical models of certain possible molecular switching devices. In this paper we work out a decomposition of soliton automata through the structure of their underlying graphs. These results lead to the original aim, to give a characterization of soliton automata in general case

Splitters and barriers in open graphs having a perfect internal matching

A counterpart of Tutte's Theorem and Berge's formula is proved for open graphs with perfect (maximum) internal matchings. Properties of barriers and factor-critical graphs are studied in the new context, and an efficient algorithm is given to find maximal barriers of graphs having a perfect internal matching

Structuring the elementary components of graphs having a perfect internal matching

AbstractGraphs with perfect internal matchings are decomposed into elementary components, and these components are given a structure reflecting the order in which they can be reached by external alternating paths. It is shown that the set of elementary components can be grouped into pairwise disjoint families determined by the “two-way accessible” relationship among them. A family tree is established by which every family member, except the root, has a unique father and mother identified as another elementary component and one of its canonical classes, from which the given member is two-way accessible. It is proved that every member of the family is only accessible through a distinguished canonical class of the root by external alternating paths. The families themselves are arranged in a partial order according to the order they can be covered by external alternating paths, and a complete characterization of the graph's forbidden and impervious edges is elaborated

On the König deficiency of zero-reducible graphs

A confluent and terminating reduction system is introduced for graphs,which preserves the number of their perfect matchings. A union-find algorithm is presented to carry out reduction in almost linear time. The König property is investigated in the context of reduction by introducing the König deficiency of a graph G as the difference between the vertex covering number and thematching number ofG. It is shown that the problem of finding the König deficiency of a graph is NP-complete even if we know that the graph reduces to the empty graph. Finally, the König deficiency of graphs G having a vertex v such that G − v has a unique perfect matching is studied in connection with reduction

Application oriented variable fixing methods for the multiple depot vehicle scheduling problem

In this article, we present heuristic methods for the vehicle scheduling problem that solve it by reducing the problem size using different variable fixing approaches. These methods are constructed in a way that takes some basic driver requirements into consideration as well. We show the efficiency of the methods on real-life and random data instances too. We also give an improved way of generating random input for the vehicle scheduling problem