Unifying single-agent and two-agent search

Single-agent and two-agent search have been studied in relative isolation from each other; each having its own distinct character. Despite the separation, a close inspection of the research shows that the two areas have actually been converging. This paper argues that the single/two-agent distinction is not the essence of heuristic search anymore. The state space is characterized by a number of key properties that are defined by the application; single- versus two-agent is just one of many.