,
Pooja Kulkarni
,
Ruta Mehta
,
Jan Vondràk
Creative Commons Attribution 4.0 International license
We consider discrete allocation problems where m indivisible goods need to be allocated among n agents. When agents' valuation functions are additive, the well-known cycle canceling lemma [Lenstra et al., 1990; Shmoys and Tardos, 1993; Plotkin et al., 1995] plays a key role in the design and analysis of rounding algorithms. In this paper, we prove an analogous lemma for the case of submodular valuations. Our algorithm removes cycles in the support graph of a fractional allocation while guaranteeing that each agent’s value, measured using the multilinear extension, does not decrease. We demonstrate applications of the cycle-canceling algorithm, along with other ideas, to obtain new algorithms and results for three well-studied allocation objectives: max-min (Santa Claus problem), Nash social welfare (NSW), and maximin-share (MMS). For the submodular NSW problem, we obtain a 1/5-approximation; for the MMS problem, we obtain a 1/2(1-1/e)-approximation through new simple algorithms. For various special cases where the goods are "small" valued or the number of agents is constant, we obtain tight/best-known approximation algorithms. All our results are in the value-oracle model.
@InProceedings{chekuri_et_al:LIPIcs.APPROX/RANDOM.2026.21,
author = {Chekuri, Chandra and Kulkarni, Pooja and Mehta, Ruta and Vondr\`{a}k, Jan},
title = {{Cycle Cancellation for Submodular Fractional Allocations and Applications}},
booktitle = {Approximation, Randomization, and Combinatorial Optimization. Algorithms and Techniques (APPROX/RANDOM 2026)},
pages = {21:1--21:20},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-449-9},
ISSN = {1868-8969},
year = {2026},
volume = {392},
editor = {Singh, Mohit and Gur, Tom},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.APPROX/RANDOM.2026.21},
URN = {urn:nbn:de:0030-drops-277384},
doi = {10.4230/LIPIcs.APPROX/RANDOM.2026.21},
annote = {Keywords: Submodular Optimization, Allocation Problems, Fair Division}
}