,
Augustin Delecluse
,
Jean-Charles Régin
,
Pierre Schaus
Creative Commons Attribution 4.0 International license
Insertion sequence variables have recently been introduced as a computational domain for modeling routing and sequencing problems in constraint programming. Typically, search heuristics guide the insertion process of new nodes into a partial growing path, while constraints eliminate infeasible insertions. This paper investigates filtering for the (minimum) distance constraint over insertion sequence variables. This global constraint links a sequence to a distance variable based on a given distance matrix. So far, only a simple filtering algorithm has been proposed, which considers the partial path but ignores mandatory nodes. Our contribution is to introduce stronger lower bounds that also take mandatory nodes into account. These bounds further enable the derivation of additional filtering rules for node insertions. An experimental evaluation on the TourMustSee problem shows that the proposed filtering rules significantly reduce the search space compared to the existing filtering approach.
@InProceedings{schmied_et_al:LIPIcs.CP.2026.49,
author = {Schmied, Margaux and Delecluse, Augustin and R\'{e}gin, Jean-Charles and Schaus, Pierre},
title = {{The Distance Constraint on Sequence Variables}},
booktitle = {32nd International Conference on Principles and Practice of Constraint Programming (CP 2026)},
pages = {49:1--49:19},
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.2026.49},
URN = {urn:nbn:de:0030-drops-266828},
doi = {10.4230/LIPIcs.CP.2026.49},
annote = {Keywords: Constraint programming, sequence variable, global constraint, cost-based constraint, distance constraint, lower bound}
}