“Rewrite Rules for Horn Programs”
K. Subramani, West Virginia University
Abstract
In this talk we discuss a simple, greedy rewrite algorithm for a class of linear programs called Horn programs. This algorithm, which we term as the “Lifting Algorithm,” runs in time O(m•n2) on a Horn system with m constraints and n variables. Inasmuch as Horn constraints subsume difference constraints, and all known algorithms for the problem of checking feasibility in difference constraint systems run in time Ω(m•n), the running time of our algorithm is only a factor n worse than the best known running time for checking feasibility in difference constraint systems. Horn programs arise in a number of application areas, including econometrics and program verification; consequently, their study is well-motivated. An important feature of our algorithm is that it uses only one operator, viz., addition. We also show that our algorithm can identify the linear and lattice point feasibility of Extended Horn Systems in O(m•n2) time.
Bio
K. Subramani is an associate professor in the Lane Department of Computer Science and Electrical Engineering at West Virginia University. His research interests lie at the intersection of automated reasoning and combinatorial optimization. He received a Ph.D. from the Department of Computer Science at the University of Maryland, College Park, in 2000.
