Title
“Almost stable” matchings in the roommates problem
Abstract
An instance of the classical Stable Roommates problem (sr) need not admit a stable matching. This motivates the problem of finding a matching that is “as stable as possible”, i.e. admits the fewest number of blocking pairs. In this paper we prove that, given an sr instance with n agents, in which all preference lists are complete, the problem of finding a matching with the fewest number of blocking pairs is NP-hard and not approximable within $n^{\frac{1}{2}-\varepsilon}$, for any ε0, unless P=NP. If the preference lists contain ties, we improve this result to n1−ε. Also, we show that, given an integer K and an sr instance I in which all preference lists are complete, the problem of deciding whether I admits a matching with exactly K blocking pairs is NP-complete. By contrast, if K is constant, we give a polynomial-time algorithm that finds a matching with at most (or exactly) K blocking pairs, or reports that no such matching exists. Finally, we give upper and lower bounds for the minimum number of blocking pairs over all matchings in terms of some properties of a stable partition, given an sr instance I.
Year
DOI
Venue
2005
10.1007/11671411_1
WAOA
Keywords
Field
DocType
roommates problem,preference list,classical stable roommates problem,integer k,stable matching,fewest number,minimum number,n agent,lower bound,sr instance,stable partition,upper and lower bounds
Integer,Stable roommates problem,Approximation algorithm,Discrete mathematics,Mathematical optimization,Combinatorics,Upper and lower bounds,Matching (graph theory),Partition (number theory),Time complexity,Mathematics,Polynomial method
Conference
Volume
ISSN
ISBN
3879
0302-9743
3-540-32207-8
Citations 
PageRank 
References 
22
1.38
9
Authors
3
Name
Order
Citations
PageRank
David J. Abraham119015.88
Péter Biró223719.83
David F. Manlove376160.45