{"type":"ScholarlyArticle","title":"Are White Knights Worth the Trouble? Reconciling POCL and Partial-Order Plans for Plan Optimization","authors":[{"name":"Harrison Oates","slug":"harrison-oates","given":"Harrison","family":"Oates","affiliation":""},{"name":"Pascal Bercher","slug":"pascal-bercher","given":"Pascal","family":"Bercher","affiliation":""}],"abstract":"Partial order causal link (POCL) planning offers rich structural representations for plan optimization. However, under the classical threat definition, POCL plans form a strict subset of valid partial-order (PO) plans. This gap limits existing POCL optimization techniques to a restricted subspace of PO solutions. We revisit 'white knight' threat semantics, which permit a causal link to persist across a threat provided the deleted condition is re-established by an intermediate producer.  We prove that under this definition, the POCL and PO solution spaces become equivalent. By extending a MaxSAT-based optimization framework, we demonstrate that white knights are theoretically necessary for completeness and practically advantageous: they yield plans with significantly fewer ordering constraints in domains with complex causal interference while maintaining computational tractability on standard benchmarks.","doi":"10.24963/ijcai.2026/688","url":"https://ijcai.org/proceedings/2026/688","pdf":"https://ijcai.org/proceedings/2026/0688.pdf","markdown":"https://ijcai.org/proceedings/2026/688.md","bibtex":"https://ijcai.org/proceedings/2026/bibtex/688","volume":{"slug":"2026","title":"Proceedings of the Thirty-Fifth International Joint Conference on Artificial Intelligence","short_title":"IJCAI 2026","url":"https://ijcai.org/proceedings/2026/","year":2026,"location":"Bremen, Germany","dates":"15-21 August 2026","editors":"Diego Calvanese","isbn":"978-1-956792-09-6","publisher":"International Joint Conferences on Artificial Intelligence Organization","doi_prefix":"10.24963/ijcai.2026"},"section":"Planning and Scheduling","track":"Main Track","number":688,"pages":{"first":6183,"last":6190},"keywords":["Planning and Scheduling: Theoretical foundations of planning"],"videos":[],"references":[],"license_note":"Copyright International Joint Conferences on Artificial Intelligence."}