Let G = (N, E) be an edge-weighted undirected graph. The graph partiti
oning problem is the problem of partitioning the node set N into k dis
joint subsets of specified sizes so as to minimize the total weight of
the edges connecting nodes in distinct subsets of the partition. We p
resent a numerical study on the use of eigenvalue-based techniques to
find upper and lower bounds for this problem. Results for bisecting gr
aphs with up to several thousand nodes are given, and for small graphs
some trisection results are presented. We show that the techniques ar
e very robust and consistently produce upper and lower bounds having a
relative gap of typically a few percentage points.