Authors: Dechter, R., I. Meiri and J. Pearl
Title: Temporal Constraint Networks
Publication: Artificial INtelligence (49) pp. 61-95
Publisher: Elsevier, Utrecht, NL
http://www.math.unipd.it/~frossi/r10.pdf
This is a great look at the implications of time in systems when one of the key constraints in the solution involves time.