Problem Solver Control Over the ATMS

Abstract

The ATMS is a powerful tool for automated problem solvers. It provides an efficient mechanism for maintaining consistent sets of beliefs and recording the assumptions underlying them. This enables the problem solver to switch rapidly between contexts and compare them. Applications to larger problems have been hampered, however, by the problem solver’s inability to maintain control over theATMS.

We present a new approach which allows the problem solver to maintain tight local and global control over both normal and nogood consumers. Local control is achieved by attaching guards to individual consumers. These guards express control, rather than logical, knowledge and consist of sets of environments. Global control is achieved by specifying a set of interesting environments. Consumers are fired only when its antecedents are true in some interesting environment. We also successfully apply the same technique to limit label propagation in the ATMS. This ensures that the ATMS respects the problem solver’s wishes and only makes derivations in interesting contexts.

This research was supported by a SIEMENS doctoral fellowship.