Matchings with lower quotas: Algorithms and complexity

Arulselvan, A., Cseh, Á., Groß, M., Manlove, D. and Matuschke, J. (2018) Matchings with lower quotas: Algorithms and complexity. Algorithmica, 80(1), pp. 185-208. (doi: 10.1007/s00453-016-0252-6)

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We study a natural generalization of the maximum weight many-to-one matching problem. We are given an undirected bipartite graph G=(A∪˙P,E)G=(A∪˙P,E) with weights on the edges in E, and with lower and upper quotas on the vertices in P. We seek a maximum weight many-to-one matching satisfying two sets of constraints: vertices in A are incident to at most one matching edge, while vertices in P are either unmatched or they are incident to a number of matching edges between their lower and upper quota. This problem, which we call maximum weight many-to-one matching with lower and upper quotas (WMLQ), has applications to the assignment of students to projects within university courses, where there are constraints on the minimum and maximum numbers of students that must be assigned to each project. In this paper, we provide a comprehensive analysis of the complexity of WMLQ from the viewpoints of classical polynomial time algorithms, fixed-parameter tractability, as well as approximability. We draw the line between NPNP-hard and polynomially tractable instances in terms of degree and quota constraints and provide efficient algorithms to solve the tractable ones. We further show that the problem can be solved in polynomial time for instances with bounded treewidth; however, the corresponding runtime is exponential in the treewidth with the maximum upper quota umaxumax as basis, and we prove that this dependence is necessary unless FPT=W[1]FPT=W[1]. The approximability of WMLQ is also discussed: we present an approximation algorithm for the general case with performance guarantee umax+1umax+1, which is asymptotically best possible unless P=NPP=NP. Finally, we elaborate on how most of our positive results carry over to matchings in arbitrary graphs with lower quotas.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Manlove, Professor David
Authors: Arulselvan, A., Cseh, Á., Groß, M., Manlove, D., and Matuschke, J.
College/School:College of Science and Engineering > School of Computing Science
Journal Name:Algorithmica
Publisher:Springer US
ISSN (Online):1432-0541
Published Online:21 November 2016
Copyright Holders:Copyright © 2016 The Authors
First Published:First published in Algorithmica 2016
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
607071Efficient Algorithms for Mechanism Design Without Monetary Transfer.David ManloveEngineering & Physical Sciences Research Council (EPSRC)EP/K010042/1COM - COMPUTING SCIENCE