EJC
2006
13 years 4 months ago
2006
1 The Ramsey number R(G1, G2) is the smallest integer p such that for any graph G on p vertices2 either G contains G1 or G contains G2, where G denotes the complement of G. In this...
EJC
2006
13 years 4 months ago
2006
The digraphs P(n, k) have vertices corresponding to length k permutations of an n set and arcs corresponding to (k + 1) permutations. Answering a question of Starling, Klerlein, K...
EJC
2006
13 years 4 months ago
2006
EJC
2006
13 years 4 months ago
2006
EJC
2006
13 years 4 months ago
2006
EJC
2006
13 years 4 months ago
2006
: Two transformations are constructed that map the permutation group onto a well-defined subset of a partially commutative monoid generated by the so-called oiseaux. Those transfor...
EJC
2006
13 years 4 months ago
2006
We introduce a large self-dual class of simplicial complexes for which we show that each member complex is contractible or homotopy equivalent to a sphere. Examples of complexes i...
EJC
2006
13 years 4 months ago
2006
The problem of counting plane trees with n edges and an even or an odd number of leaves has been recently studied by Eu, Liu and Yeh, in connection with an identity on coloring ne...
EJC
2006
13 years 4 months ago
2006
Abstract. We start with a bijective proof of Schur's theorem due to Alladi and Gordon and describe how a particular iteration of it leads to some very general theorems on colo...
EJC
2006
13 years 4 months ago
2006
Abstract. A leaf of a plane tree is called an old leaf if it is the leftmost child of its parent, and it is called a young leaf otherwise. In this paper we enumerate plane trees wi...