@techreport{bjrner2008modular,
author = {Bjørner, Nikolaj and Blass, Andreas and Gurevich, Yuri and Musuvathi, Madan},
title = {Modular difference logic is hard},
year = {2008},
month = {October},
abstract = {In connection with machine arithmetic, we are interested in systems of constraints of the form x + k ≤ y + l. Over integers, the satisfiability problem for such systems is polynomial time. The problem becomes NP complete if we restrict attention to the residues for a fixed modulus N.},
url = {http://approjects.co.za/?big=en-us/research/publication/modular-difference-logic-is-hard/},
pages = {8},
number = {MSR-TR-2008-140},
}