EJC
2008
13 years 4 months ago
2008
The motivation for this paper is three-fold. First, we study the connectivity properties of the homomorphism order of directed graphs, and more generally for relational structures...
EJC
2008
13 years 4 months ago
2008
EJC
2008
13 years 4 months ago
2008
Wang and Lih conjectured that for every g 5, there exists a number M(g) such that the square of a planar graph G of girth at least g and maximum degree M(g) is (+1)-colorable. ...
EJC
2008
13 years 4 months ago
2008
EJC
2008
13 years 4 months ago
2008
Given the set [n] = {1, . . . , n} for positive integer n, combinatorial properties of Clifford algebras are exploited to count partitions and nonoverlapping partitions of [n]. Th...
EJC
2008
13 years 4 months ago
2008
We present a combinatorial proof of Postnikov's hook length formula for binary trees. c 2007 Elsevier Ltd. All rights reserved. Let [n] = {1, 2, . . . , n}. It is well known ...
EJC
2008
13 years 4 months ago
2008
Let D be a set of positive integers. The distance graph generated by D, denoted by G(Z, D), has the set Z of all integers as the vertex Supported in part by the National Science ...
EJC
2008
13 years 4 months ago
2008
A linear deformation of a Meyer set M in Rd is the image of M under a group homomorphism of the group [M] generated by M into Rd . We provide a necessary and sufficient condition f...
EJC
2008
13 years 4 months ago
2008
We investigate the following vertex percolation process. Starting with a random regular graph of constant degree, delete each vertex independently with probability p, where p = n-...
EJC
2008
13 years 4 months ago
2008
A graph may be the Kronecker cover in more than one way. In this note we explore this phenomenon and apply it to show that the minimal common cover of two graphs need not be uniqu...