{"type":"ScholarlyArticle","title":"New Sequence-Independent Lifting Techniques for Cover Inequalities and When They Induce Facets","authors":[{"name":"Siddharth Prasad","slug":"siddharth-prasad","given":"Siddharth","family":"Prasad","affiliation":""},{"name":"Ellen Vitercik","slug":"ellen-vitercik","given":"Ellen","family":"Vitercik","affiliation":""},{"name":"Maria-Florina Balcan","slug":"maria-florina-balcan","given":"Maria-Florina","family":"Balcan","affiliation":""},{"name":"Tuomas Sandholm","slug":"tuomas-sandholm","given":"Tuomas","family":"Sandholm","affiliation":""}],"abstract":"Sequence-independent lifting is a procedure for strengthening valid inequalities of an integer program. We generalize the sequence-independent lifting method of Gu, Nemhauser, and Savelsbergh (GNS lifting) for cover inequalities and correct an error in their proposed generalization. We obtain a new sequence-independent lifting technique---piecewise-constant (PC) lifting---with a number of important properties. We derive a broad set of sufficient conditions under which PC lifting yields facets---the first characterization of facet-defining sequence-independent liftings that are efficiently computable from the underlying cover. Finally, we demonstrate via experiments that PC lifting can be a useful alternative to GNS lifting. We test PC lifting atop a number of novel cover inequality generation routines, which prove to be effective in experiments with CPLEX. PC lifting delivers strong numerical properties making it practically relevant for integer programming solvers.","doi":"10.24963/ijcai.2025/298","url":"https://ijcai.org/proceedings/2025/298","pdf":"https://ijcai.org/proceedings/2025/0298.pdf","markdown":"https://ijcai.org/proceedings/2025/298.md","bibtex":"https://ijcai.org/proceedings/2025/bibtex/298","volume":{"slug":"2025","title":"Proceedings of the Thirty-Fourth International Joint Conference on Artificial Intelligence","short_title":"IJCAI 2025","url":"https://ijcai.org/proceedings/2025/","year":2025,"location":"Montreal, Canada","dates":"16-22 August 2025","editors":"James Kwok","isbn":"978-1-956792-06-5","publisher":"International Joint Conferences on Artificial Intelligence Organization","doi_prefix":"10.24963/ijcai.2025"},"section":"Constraint Satisfaction and Optimization","track":"Main Track","number":298,"pages":{"first":2675,"last":2683},"keywords":["Constraint Satisfaction and Optimization: CSO: Mixed discrete and continuous optimization","Search: S: Combinatorial search and optimisation","Constraint Satisfaction and Optimization: CSO: Solvers and tools","Constraint Satisfaction and Optimization: CSO: Constraint optimization problems"],"videos":[],"references":[],"license_note":"Copyright International Joint Conferences on Artificial Intelligence."}