This work has been supported in part by the National Science Foundation under grants BIR 940-2380 and CDA 9414015. We wish to thank Sun Microsystems, Silicon Graphics, and Cray Research for allowing us to access their machines for these experiments. We wish to thank members of the Arabidopsis sequencing group at Michigan State University and the genomic database group at the University of Minnesota for their advice and suggestions. We wish also to thank Warren Gish and Vipin Kumar for helpful discussion.