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EJC
2006
14 years 9 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...
EJC
2006
14 years 9 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
2000
14 years 9 months ago
2000
We study the zeros of two families of polynomials related to rook theory and matchings in graphs. One of these families is based on the cover polynomial of a digraph introduced by ...
EJC
2000
14 years 9 months ago
2000
For general polytopes, it has turned out that with respect to many questions it su ces to consider only the simple polytopes, i.e., d-dimensional polytopes where every vertex is c...
EJC
2002
14 years 9 months ago
2002
A subgraph H of a graph G is gated if for every x V(G) there exists a vertex u in H such that dG (x, v) = dG (x, u) + d G (u, v) for any v V(H). The gated amalgam of graphs G 1 an...