Modular difference logic is hard
- Nikolaj Bjørner ,
- Andreas Blass ,
- Yuri Gurevich ,
- Madan Musuvathi
MSR-TR-2008-140 |
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.