Double Precedence Graphs

Reasoning on precedence relations is crucial for many planning and scheduling systems. In this paper we propose a double precedence graph where direct precedence relations are kept in addition to traditional precedence relations. By the direct precedence between activities A and B we mean that A directly precedes B (no activity is between A and B). We also show how these direct precedence relations can be used in incremental filtering of time windows and in introducing sequencedependent setup times between activities.