Graphs and Combinatorics

, Volume 33, Issue 2, pp 473–484 | Cite as

Rainbow Matchings and Algebras of Sets

  • Gabriel Nivasch
  • Eran Omri
Original Paper


Grinblat (Algebras of Sets and Combinatorics, Translations of Mathematical Monographs, vol. 214. AMS, Providence, 2002) asks the following question in the context of algebras of sets: What is the smallest number \(\mathfrak {v} = \mathfrak {v}(n)\) such that, if \(A_1, \ldots , A_n\) are n equivalence relations on a common finite ground set X, such that for each i there are at least \(\mathfrak {v}\) elements of X that belong to \(A_i\)-equivalence classes of size larger than 1, then X has a rainbow matching—a set of 2n distinct elements \(a_1, b_1, \ldots , a_n, b_n\), such that \(a_i\) is \(A_i\)-equivalent to \(b_i\) for each i? Grinblat has shown that \(\mathfrak {v}(n) \le 10n/3 + O(\sqrt{n})\). He asks whether \(\mathfrak {v}(n) = 3n-2\) for all \(n\ge 4\). In this paper we improve the upper bound (for all large enough n) to \(\mathfrak {v}(n) \le 16n/5 + O(1)\).


Equivalence Class Equivalence Relation Pairwise Disjoint Distinct Element Combinatorial Problem 
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Thanks to L. Š. (Yehuda) Grinblat for suggesting us to look at this problem and for helpful discussions. Special thanks to the referees for reading the paper carefully and providing detailed suggestions. Thanks also to Anat Paskin-Cherniavsky for helpful discussions.


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Copyright information

© Springer Japan 2017

Authors and Affiliations

  1. 1.Department of Computer ScienceAriel UniversityArielIsrael

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