Speaker:  Alan C.H. Ling University of Vermont
Time and Place: 18 Nov. 2005, 12:00 noon, HP4351, Herzberg building, Carleton University

Title:  The existence of resolvable graph designs
Abstract:  

Let v >= k and m be positive integers. A block design
BD(v,k,m) is a collection A of k-subsets
of a v-set X in which every unordered
pair of elements from X is contained in exactly m elements of A.
More
generally, for a fixed simple graph G, a graph design GD(v,G,m) is a collection A of graphs isomorphic
to G with vertices in X such that every unordered
pair of elements from X is an edge of exactly m elements
of A. A famous result
of Wilson says that for a fixed G and m, there exists a GD(v,G,m) for all sufficiently large
v satisfying certain necessary conditions. A block (graph) design as
above is said to be resolvable if A can be
partitioned into partitions of (graphs
whose vertex sets partition) X. Lu has shown asymptotic existence of resolvable
 BD(v,k,m), yet
for over twenty years the analogous problem for resolvable GD(v,k,m) has remained open. In this
 paper, we settle asymptotic existence of resolvable graph
designs.