Preference Swaps for the Stable Matching Problem

Eduard Eiben; Gregory Gutin; Philip R. Neary; Clément Rambaud; Magnus Wahlström; Anders Yeo

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arXiv · 2112.15361

Preference Swaps for the Stable Matching Problem

Eduard Eiben·Gregory Gutin·Philip R. Neary·Clément Rambaud·Magnus Wahlström·Anders Yeo

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Abstract

An instance $I$ of the Stable Matching Problem (SMP) is given by a bipartite graph with a preference list of neighbors for every vertex. A swap in $I$ is the exchange of two consecutive vertices in a preference list. A swap can be viewed as a smallest perturbation of $I$. Boehmer et al. (2021) designed a polynomial-time algorithm to find the minimum number of swaps required to turn a given maximal matching into a stable matching. We generalize this result to the many-to-many version of SMP. We do so first by introducing a new representation of SMP as an extended bipartite graph and subsequently by reducing the problem to submodular minimization. It is a natural problem to establish the computational complexity of deciding whether at most $k$ swaps are enough to turn $I$ into an instance where one of the maximum matchings is stable. Using a hardness result of Gupta et al. (2020), we prove that this problem is NP-hard and, moreover, this problem parameterised by $k$ is W[1]-hard. We also obtain a lower bound on the running time for solving the problem using the Exponential Time Hypothesis.

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Eduard Eiben, Gregory Gutin, Philip R. Neary, Clément Rambaud, Magnus Wahlström, Anders Yeo. 2021-12-31. Preference Swaps for the Stable Matching Problem. https://arxiv.org/abs/2112.15361

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