Closure conditions of commutativity
There are investigated some closure conditions of Thomsen type in 3-webs which gurantee that at least one of coordinatizing quasigroups of a given 3-web is commutative.
Closure for spanning trees and distant area
A k-ended tree is a tree with at most k endvertices. Broersma and Tuinstra [3] have proved that for k ≥ 2 and for a pair of nonadjacent vertices u, v in a graph G of order n with , G has a spanning k-ended tree if and only if G+uv has a spanning k-ended tree. The distant area for u and v is the subgraph induced by the set of vertices that are not adjacent with u or v. We investigate the relationship between the condition on and the structure of the distant area for u and v. We prove that if the...
Clusters in a multigraph with elevated density.
Co prime path decomposition number of a graph.
Coalescence of difans and diwheels.
Coalescents with simultaneous multiple collisions.
Coalescing Fiedler and core vertices
The nullity of a graph is the multiplicity of zero as an eigenvalue in the spectrum of its adjacency matrix. From the interlacing theorem, derived from Cauchy’s inequalities for matrices, a vertex of a graph can be a core vertex if, on deleting the vertex, the nullity decreases, or a Fiedler vertex, otherwise. We adopt a graph theoretical approach to determine conditions required for the identification of a pair of prescribed types of root vertices of two graphs to form a cut-vertex of unique...
Coassociative grammar, periodic orbits, and quantum random walk over .
Codes and designs from triangular graphs and their line graphs
For any prime p, we consider p-ary linear codes obtained from the span over p of rows of incidence matrices of triangular graphs, differences of the rows and adjacency matrices of line graphs of triangular graphs. We determine parameters of the codes, minimum words and automorphism groups. We also show that the codes can be used for full permutation decoding.
Codes, lattices, and Steiner systems.
Codes that attain minimum distance in every possible direction
The following problem motivated by investigation of databases is studied. Let be a q-ary code of length n with the properties that has minimum distance at least n − k + 1, and for any set of k − 1 coordinates there exist two codewords that agree exactly there. Let f(q, k)be the maximum n for which such a code exists. f(q, k)is bounded by linear functions of k and q, and the exact values for special k and qare determined.
Coding parking functions by pairs of permutations.
Coefficients of functional compositions often grow smoothly.
Coelevation of a graph
Cohen-Macauly Graphs.
Coherent configurations I
Cohomologie de Hochschild des graphes de Kontsevich
Nous calculons la cohomologie de Hochschild directement sur les graphes de Kontsevich. Celle-ci est localisée sur les graphes totalement antisymétriques ayant autant de pieds que de pattes. La considération de cette cohomologie permet de réinterpréter l’équation de formalité pour l’espace .
Cohomology with free coefficients of the fundamental group of a graph of groups.
Collapsing along monotone poset maps.
Collineations and Extensions of Translation Nets.