Querying Temporal Constraint Networks in PTIME

Manolis Koubarakis, Spiros Skiadopoulos

Abstract: We start with the assumption that temporal knowledge usually cared by constraint networks can be represented and queried more effectively by using the scheme of indefinite constraint databases proposed by Koubarakis. Although query evaluation in this scheme is in general a hard computational problem, we demonstrate that there are sevral interesting cases where query evalation can be done in PTIME. These tractability results are original and subsume previous results by van Beek, Brusoni, Console and Terenziani.