We study a variation of the graph coloring problem on random graphs of finite average connectivity. Given the number of colors, we aim to maximize the number of different colors at neighboring vertices (i.e., one edge distance) of any vertex. Two efficient algorithms, belief propagation and Walksat, are adapted to carry out this task. We present experimental results based on two types of random...

Zero-knowledge proof is a very interesting problem in modern cryptography, which attracts the attention of many cryptographers, and there are plenty of researches. It is one of the hot research field in cryptography. First, we made a simple introduction of zero-knowledge proof. Then we had given a perfect quantum zero knowledge proof system on a specific NP – complete problem "graph 3-coloring"...

We combine a parallel algorithm for the two processor scheduling problem, which runs in polylog time on a polynomial number of processors, with an algorithm to find transitive orientations of graphs where they exist. Both algorithms together solve the maximum clique problem and the minimum coloring problem for comparability graphs, and the maximum matching problem for co-comparability graphs. T...

‎For a coloring $c$ of a graph $G$‎, ‎the edge-difference coloring sum and edge-sum coloring sum with respect to the coloring $c$ are respectively‎ ‎$sum_c D(G)=sum |c(a)-c(b)|$ and $sum_s S(G)=sum (c(a)+c(b))$‎, ‎where the summations are taken over all edges $abin E(G)$‎. ‎The edge-difference chromatic sum‎, ‎denoted by $sum D(G)$‎, ‎and the edge-sum chromatic sum‎, ‎denoted by $sum S(G)$‎, ‎a...

A hole is a chordless cycle with at least four vertices. A hole is odd if it has an odd number of vertices. A banner is a graph which consists of a hole on four vertices and a single vertex with precisely one neighbor on the hole. We prove that a (banner, odd hole)-free graph is either perfect, or does not contain a stable set on three vertices, or contains a homogeneous set. Using this structu...

This paper extends the Birkhoff-von Neumann unicast switching strategy to the multicast case. Using a graph theoretic model we show that the rate region for a traffic pattern is precisely the stable set polytope of the pattern’s ‘conflict graph’, in the no-fanout splitting case. Computing the offline schedule is equivalent to fractional weighted graph coloring which takes polynomial time for pe...

We introduce the notion of a of a hypergraph, which is a subset of vertices to be colored so that at least two vertices are of the same color. Hypergraphs with both and are called mixed hypergraphs. The maximal number of colors for which there exists a mixed hypergraph coloring using all the colors is called the upper chromatic number of a hypergraph H and is denoted by X(H). An algorithm for c...

A perfect matching covering of a graph G is a set of perfect matchings of G such that every edge of G is contained in at least one member of it. Berge conjectured that every bridgeless cubic graph admits a perfect matching covering of order at most 5 (we call such a collection of perfect matchings a Berge covering of G). A cubic graph G is called a Kotzig graph if G has a 3-edge-coloring such t...