DM
2002
13 years 4 months ago
2002
We consider the vertex-isoperimetric problem for cartesian powers of a graph G. A total order on the vertex set of G is called isoperimetric if the boundary of sets of a given siz...
DM
2002
13 years 4 months ago
2002
DM
2002
13 years 4 months ago
2002
A generalized p-cycle is a digraph whose set of vertices can be partitioned into p parts that are cyclically ordered in such a way that the vertices in one part are adjacent only ...
DM
2002
13 years 4 months ago
2002
DM
2002
13 years 4 months ago
2002
Let G be a tree and let H be a collection of subgraphs of G, each having at most d connected components. Let (H) denote the maximum number of members of H no two of which share a ...
DM
2002
13 years 4 months ago
2002
DM
2002
13 years 4 months ago
2002
DM
2002
13 years 4 months ago
2002
We show that the average size of subsets of [n] forming an intersecting Sperner family of cardinality not less than (n-1 k-1 ) is at least k provided that k 6 n=2