Recognizing halved cubes in a constant time per edge

AbstractGraphs that can be isometrically embedded into the metric space l1 are called l1-graphs. Halved cubes play an important role in the characterization of l1-graphs. We present an algorithm that recognizes halved cubes in O(n log2 n) time

How Well Can Ants Color Graphs?

We compare the ants algorithm for graph coloring recently proposed by Costa and Hertz with the repeated Recursive Largest First algorithm and with a Petford- Welsh type algorithm. In our experiments, the latter is much better than the first two

General Position Sets in Two Families of Cartesian Product Graphs

For a given graph G, the general position problem asks for the largest set of vertices S⊆V(G) , such that no three distinct vertices of S belong to a common shortest path of G. The general position problem for Cartesian products of two cycles as well as for hypercubes is considered. The problem is completely solved for the first family of graphs, while for the hypercubes, some partial results based on reduction to SAT are given

1-factors and characterization of reducible faces of plane elementary bipartite graphs

As a general case of molecular graphs of benzenoid hydrocarbons, we study plane bipartite graphs with Kekulé structures (1-factors). A bipartite graph ▫$G$▫ is called elementary if ▫$G$▫ is connected and every edge belongs to a 1-factor of ▫$G$▫. Some properties of the minimal and the maximal 1-factor of a plane elementary graph are given. A peripheral face ▫$f$▫ of a plane elementary graph is reducible, if the removal of the internal vertices and edges of the path that is the intersection of ▫$f$▫ and the outer cycle of ▫$G$▫ results in an elementary graph. We characterize the reducible faces of a plane elementary bipartite graph. This result generalizes the characterization of reducible faces of an elementary benzenoid graph

Embedding of complete and nearly complete binary trees into hypercubes

A new simple algorithm for optimal embedding of complete binary trees into hypercubes as well as a node-by-node algorithm for embedding of nearly complete binary trees into hypercubes are presented

Fibonacci dimension of the resonance graphs of catacondensed benzenoid graphs

The Fibonacci dimension ▫$text{fdim}(G)$▫ of a graph ▫$G$▫ was introduced [in S. Cabello, D. Eppstein, S. Klavžar, The Fibonacci dimension of a graph Electron. J. Combin., 18 (2011) P 55, 23 pp] as the smallest integer ▫$d$▫ such that ▫$G$▫ admits an isometric embedding into ▫$Gamma_d$▫, the ▫$d$▫-dimensional Fibonacci cube. The Fibonacci dimension of the resonance graphs of catacondensed benzenoid systems is studied. This study is inspired by the fact, that the Fibonacci cubes are precisely the resonance graphs of a subclass of the catacondensed benzenoid systems. Our results show that the Fibonacci dimension of the resonance graph of a catacondensed benzenoid system ▫$G$▫ depends on the inner dual of ▫$G$▫. Moreover, we show that computing the Fibonacci dimension can be done in linear time for a graph of this class