Exploiting a Graphplan framework in temporal planning
Derek Long, Maria Fox · Strathprints: The University of Strathclyde institutional repository (University of Strathclyde) · 2003
Graphplan (Blum & Furst 1995) has proved a popular and successful basis for a succession of extensions. An extension to handle temporal planning is a natural one to consider, be-cause of the seductively time-like structure of the layers in the plan graph. TGP (Smith & Weld 1999) and TPSys (Gar-rido, Onaindı́a, & Barber 2001; Garrido, Fox, & Long 2002) are both examples of temporal planners that have exploited the Graphplan foundation. However, both of these systems (including both versions of TPSys) exploit the graph to rep-resent a uniform flow of time. In this paper we describe an alternative approach, in which the graph is used to repre-sent the purely logical structuring of the plan, with tempo-ral constraints being managed separately (although not inde-pendently). The approach uses a linear constraint solver to ensure that temporal durations are correctly respected. The resulting planner offers an interesting alternative to the other approaches, offering an important extension in expressive power.