Department of Computer Science, Iowa State University, Ames, IA 50011, USA. rjordan@iastate.edu|Department of Computer Science, Iowa State University, Ames, IA 50011, USA. rjordan@iastate.edu|Department of Computer Science, Iowa State University, Ames, IA 50011, USA. rjordan@iastate.edu|Department of Computer Science, Iowa State University, Ames, IA 50011, USA. rjordan@iastate.edu