Colourful matchings

TL;DR

This paper investigates the existence of balanced matchings in highly conflicting committee proposals and explores related combinatorial and embedding problems in large Steiner systems.

Contribution

It introduces an asymptotic framework for balanced matchings under extreme disagreement and examines implications for combinatorial design embedding problems.

Findings

Existence of approximate balanced matchings under certain conditions

Connections between matchings and Steiner system configurations

New variants of combinatorial matching problems

Abstract

Suppose a committee consisting of three members has to match $n$ candidates to $n$ different positions. Each member of the committee proposes a matching, however the proposed matchings totally disagree, i.e., every candidate is matched to three different positions according to three committee members. All three committee members are very competitive and want to push through as many of their suggestions as possible. Can a committee always find a compromise -- a matching of candidates to positions such that for every committee member a third of all candidates are assigned according to that committee member suggestion? We will consider an asymptotic version of this question and several other variants of similar problem. As an application we will consider an embedding problem -- in particular which configurations large Steiner systems always need to contain.