Optimising Partial-Order Plans Via Action Reinstantiation

Abstract

<jats:p>This work investigates the problem of optimising a partial-order plan’s (POP) flexibility through the simultaneous transformation of its action ordering and variable binding constraints. While the former has been extensively studied through the notions of deordering and reordering, the latter has received much less attention. We show that a plan’s variable bindings are often related to resource usage and their reinstantiation can yield more flexible plans. To do so, we extend existing POP optimality criteria to support variable reinstantiation, and prove that checking if a plan can be optimised further is NP-complete. We also propose a MaxSAT-based technique for increasing plan flexibility and provide a thorough experimental evaluation that suggests that there are benefits in action reinstantiation.</jats:p>

Hierarchical planning and reasoning about partially ordered plans—From theory to practice

“…POCL plans have several applications, but are mostly used today for plan optimization techniques (Siddiqui and Haslum 2015; Muise, Beck, and McIlraith 2016; Waters et al. 2018; Waters, Padgham, and Sardina 2020).…”

“…Here, plans are not totally ordered action sequences, but only partially ordered as for example shown in Figure 2. POCL plans have several applications, but are mostly used today for plan optimization techniques (Siddiqui and Haslum 2015;Muise, Beck, and McIlraith 2016;Waters et al 2018;Waters, Padgham, and Sardina 2020).…”

A Closer Look at Causal Links: Complexity Results for Delete-Relaxation in Partial Order Causal Link (POCL) Planning

“…Only loosely related to our problem are various complexity investigations regarding plan optimization. POCL plans are particularly attractive for reasoning about plan optimization since causal links explicitly represent the causal relationships between actions (Waters, Padgham, and Sardina 2020;Waters et al 2018;Muise, Beck, and McIlraith 2016). One work investigates the computational hardness for optimizing the action set of a POCL plan (Olz and Bercher 2019), whereas several works investigate the computational hardness of optimizing ordering constraints or execution time (makespan) for partially ordered plans and POCL plans in particular (Bercher and Olz 2020;Aghighi and Bäckström 2017;Bäckström 1998).…”