New lower bounds for some multicolored Ramsey numbers.
New lower bounds on the weighted chromatic number of a graph
In this paper we present theoretical and algorithmic results for the computation of lower bounds on the chromatic number of a weighted graph. In particular, we study different ways of a possible improvement of the lower bound offered by a maximum weighted clique. Based on our findings we devise new algorithms and show their performance on random graphs.
New optimal constant weight codes.
New prolific constructions of strongly regular graphs.
New proof of a characterization of geodetic graphs
In [3], the present author used a binary operation as a tool for characterizing geodetic graphs. In this paper a new proof of the main result of the paper cited above is presented. The new proof is shorter and simpler.
New proofs of the uniqueness of extremal noneven digraphs.
New regular partial difference sets and strongly regular graphs with parameters and .
New results about impartial solitaire clobber
Impartial Solitaire Clobber is a one-player version of the combinatorial game Clobber, introduced by Albert et al. in 2002. The initial configuration of Impartial Solitaire Clobber is a graph, such that there is a stone placed on each of its vertex, each stone being black or white. A move of the game consists in picking a stone, and clobbering an adjacent stone of the opposite color. By clobbering we mean that the clobbered stone is removed from the graph, and replaced by the clobbering one....
New results about set colorings of graphs.
New results on generalized graph coloring.
New sufficient conditions for hamiltonian and pancyclic graphs
For a graph G of order n we consider the unique partition of its vertex set V(G) = A ∪ B with A = {v ∈ V(G): d(v) ≥ n/2} and B = {v ∈ V(G):d(v) < n/2}. Imposing conditions on the vertices of the set B we obtain new sufficient conditions for hamiltonian and pancyclic graphs.
New Symmetric (61,16,4) Designs Invariant Under the Dihedral Group of Order 10
∗ This work has been partially supported by the Bulgarian NSF under Contract No. I-506/1995.In this note we construct five new symmetric 2-(61,16,4) designs invariant under the dihedral group of order 10. As a by-product we obtain 25 new residual 2-(45,12,4) designs. The automorphism groups of all new designs are computed.
New symmetric designs from regular Hadamard matrices.
New theorems for signless Laplacian eigenvalues
New upper bound for a class of vertex Folkman numbers.
New Upper Bound for the Edge Folkman Number Fe(3,5;13)
2000 Mathematics Subject Classification: 05C55.For a given graph G let V(G) and E(G) denote the vertex and the edge set of G respevtively. The symbol G e → (a1, …, ar) means that in every r-coloring of E(G) there exists a monochromatic ai-clique of color i for some i ∈ {1,…,r}. The edge Folkman numbers are defined by the equality Fe(a1, …, ar; q) = min{|V(G)| : G e → (a1, …, ar; q) and cl(G) < q}. In this paper we prove a new upper bound on the edge Folkman number Fe(3,5;13), namely Fe(3,5;13)...
New Upper Bounds for Some Spherical Codes
The maximal cardinality of a code W on the unit sphere in n dimensions with (x, y) ≤ s whenever x, y ∈ W, x 6= y, is denoted by A(n, s). We use two methods for obtaining new upper bounds on A(n, s) for some values of n and s. We find new linear programming bounds by suitable polynomials of degrees which are higher than the degrees of the previously known good polynomials due to Levenshtein [11, 12]. Also we investigate the possibilities for attaining the Levenshtein bounds [11, 12]. In such cases...
New upper bounds for the crossing number of on the Klein bottle
New upper bounds for the size of permutation codes via linear programming.
New upper bounds on the order of cages.