# Edge-finding

The edge-finding rule is a constraint propagation technique that consists of deducing whether an activity $LaTeX: a_i$ can, cannot, or must be executed before or after a set of activities $LaTeX: \Omega, a_i \notin \Omega$ that all (including $LaTeX: a_i$) require the same resource. Two types of conclusions can then be drawn: new ordering relations (“edges” in the graph representing the possible orderings of activities) and new time-bounds (i.e., tightening of the earliest and latest start and end times of activities).