Creative Commons Attribution 4.0 International license
Cumulative constraints are central in scheduling with constraint programming, yet propagation is typically performed per constraint, missing multi-resource interactions and causing severe slowdowns on some benchmarks. I present a preprocessing method for inferring additional cumulative constraints that capture such interactions without search-time probing. This approach interprets cumulative constraints as linear inequalities over occupancy vectors and generates valid inequalities by (i) discovering covers, the sets of tasks that cannot run in parallel, (ii) strengthening the cover inequalities for the discovered sets with lifting, and (iii) injecting the resulting constraints back into the scheduling problem instance. Experiments on standard RCPSP and RCPSP/max test suites show that these inferred constraints improve search performance and tighten objective bounds on favorable instances, while exhibiting more stable performance on unfavorable instances than the prior work. Additionally, these experiments discover 25 new lower bounds and five new best solutions; seven of the lower bounds are obtained directly from the inferred constraints.
@InProceedings{sidorov:LIPIcs.CP.2026.50,
author = {Sidorov, Konstantin},
title = {{On Inferring Cumulative Constraints}},
booktitle = {32nd International Conference on Principles and Practice of Constraint Programming (CP 2026)},
pages = {50:1--50:23},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-432-1},
ISSN = {1868-8969},
year = {2026},
volume = {379},
editor = {Beldiceanu, Nicolas},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2026.50},
URN = {urn:nbn:de:0030-drops-266837},
doi = {10.4230/LIPIcs.CP.2026.50},
annote = {Keywords: Constraint programming, scheduling, cumulative, lifting, valid inequalities}
}