TR-2021-10

Polynomially tractable cases in the popular roommates problem

Erika Renáta Bérczi-Kovács, Ágnes Cseh, Kata Kosztolányi, Attila Edmund Mályusz



Abstract

The input of the popular roommates problem consists of a graph $G = (V, E)$ and for each vertex $v\in V$, strict preferences over the neighbors of~$v$. Matching $M$ is more popular than $M'$ if the number of vertices preferring $M$ to $M'$ is larger than the number of vertices preferring $M'$ to~$M$. A matching $M$ is called \emph{popular} if there is no matching~$M'$ that is more popular than~$M$.
 
Only recently Faenza et al.~\cite{FKPZ19} and Gupta et al.~\cite{GMSZ21} resolved the long-standing open question on the complexity of deciding whether a popular matching exists in a popular roommates instance and showed that the problem is $\NP$-complete. In this paper we identify a class of instances that admit a polynomial-time algorithm for the problem. We also test these theoretical findings on randomly generated instances to determine the existence probability of a popular matching in them.


Bibtex entry:

@techreport{egres-21-10,
AUTHOR = {B{\'e}rczi-Kov{\'a}cs Ren{\'a}ta, Erika and Cseh, Ágnes and Kosztol{\'a}nyi, Kata and M{\'a}lyusz Edmund, Attila},
TITLE = {Polynomially tractable cases in the popular roommates problem},
NOTE= {{\tt egres.elte.hu}},
INSTITUTION = {Egerv{\'a}ry Research Group, Budapest},
YEAR = {2021},
NUMBER = {TR-2021-10}
}


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