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