A conjecture of Erdős, Gyárfás, and Pyber says that in any edge-colouring of a complete graph with r colours, it is possible to cover all the vertices with r vertexdisjoint monochromatic cycles. So far, this conjecture has been proven only for r = 2. In this paper we show that in fact this conjecture is false for all r ≥ 3. In contrast to this, we show that in any edge-colouring of a complete g...

Davis, R. and A. Prieditis, The expected length of a shortest path, Information Processing Letters 46 (1993) 135-141. We derive an exact summation formula and a closed-form approximation for the expected length of a shortest path for a complete graph where the arc lengths are independent and exponentially distributed random variables. Experimental data validates both results. The property of co...

Longest directed path length (LDPL) is de ned by the length of the longest path of the directed acyclic graph of a given undirected graph. The LDPL of a graph measures the parallelization for the lexicographically rst maximal subgraph (LFMS) problems. That is, the parallel complexity of the problems gradually increases as the value measured on a graph grows; the LFMS problems are in NC on graph...

Polar graphs are a natural extension of some classes of graphs like bipartite graphs, split graphs and complements of bipartite graphs. A graph is (s, k)-polar if there exists a partition A, B of its vertex set such that A induces a complete s-partite graph (i.e., a collection of at most s disjoint stable sets with complete links between all sets) and B a disjoint union of at most k cliques (i....

In this paper‎, ‎we introduce a new type of graph contraction using a special class of functions and give a best proximity point theorem for this contraction in complete metric spaces endowed with a graph under two different conditions‎. ‎We then support our main theorem by a non-trivial example and give some consequences of best proximity point of it for usual graphs.

Let a graph G = (V;E) be given. In the path center problem we want to find a path P in G such that the maximum weighted distance of P to every vertex in V is minimized. In this paper a genetic algorithm and ahybrid of genetic and ant colony algorithms are presented for the path center problem. Some test problems are examined to compare the algorithms. The results show that for almost all exampl...

A number of combinatorial problems are treated using properties of abelian nilpotentand idempotent-generated subalgebras of Clifford algebras. For example, the problem of deciding whether or not a graph contains a Hamiltonian cycle is known to be NP-complete. By considering entries of Λ, where Λ is an appropriate nilpotent adjacency matrix, the k-cycles in any finite graph are recovered. Within...

A graph G is randomly traceable from one of its vertices v if every path in G starting at v can be extended to a hamiltonian path of G that starts at v. A complete classification of these graphs will be given, and some corollaries will be stated. Also, a few related concepts will be briefly discussed.

‎in this paper we introduce the concept of order difference interval graph $gamma_{odi}(g)$ of a group $g$‎. ‎it is a graph $gamma_{odi}(g)$ with $v(gamma_{odi}(g)) = g$ and two vertices $a$ and $b$ are adjacent in $gamma_{odi}(g)$ if and only if $o(b)-o(a) in [o(a)‎, ‎o(b)]$‎. ‎without loss of generality‎, ‎we assume that $o(a) leq o(b)$‎. ‎in this paper we obtain several properties of $gamma_...