1Department of Computer Science University of Alabama in Huntsville Huntsville, AL 35899-0001
2Department of Mathematics Southern JIlinois University at Carbondale Carbondale, IL 62901-4408
3 Department of Mathematical Sciences Michigan Technological University Houghton, MI 49931-1295
4Department of Computer Science University of Alabama in Huntsville Huntsville, AL 35899-0001
5Department of Mathematical Sciences University of Alabama in Huntsville Huntsville, AL 35899-0001