1. Department of Computer Science and Engineering, The Pennsylvania State University, 231 Pond Lab., University Park, PA 16802, USA
2. Coordinated Science Laboratory, University of Illinois, 1308 W. Main St., Urbana, IL 61801, USA
3. Semiconductor Systems Design Technology, Motorola Inc., Mail Drop OE 321, 6501 William Cannon Drive W., Austin, TX 78735-8598, USA