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Proceedings of the American Mathematical Society

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Simultaneous systems of representatives for finite families of finite sets


Author: Xing De Jia
Journal: Proc. Amer. Math. Soc. 104 (1988), 33-36
MSC: Primary 05A05; Secondary 11B99
DOI: https://doi.org/10.1090/S0002-9939-1988-0958037-4
MathSciNet review: 958037
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Abstract: Let $ h \geq 2$ and $ k \geq 1$. It is proved that if $ \mathcal{S} = \{ {S_i}\} _{i = 1}^s$ and $ \mathcal{T} = \{ {T_j}\} _{j = 1}^t$ are two families of nonempty, pairwise disjoint sets such that $ \vert{S_i}\vert \leq h,\vert{T_j}\vert \leq k$ and $ {S_i} \nsubseteq {T_j}$ for all $ i$ and $ j$, then the number $ N(\mathcal{S},\mathcal{T})$ of the sets $ X$ such that $ X$ is a minimal system of representatives for $ \mathcal{S}$ and $ X$ is simultaneously a system of representatives for $ \mathcal{T}$ that satisfies $ N(\mathcal{S},\mathcal{T}) \leq {h^s}{(1 - (h - r)/{h^{q + 1}})^t}$, where $ k = q(h - 1) + r$ with $ 0 \leq r \leq h - 2$. This was conjectured by M. B. Nathanson [3] in 1985.


References [Enhancements On Off] (What's this?)

  • [1] P. Erdös and M. B. Nathanson, Systems of distinct representatives and minimal bases in additive number theory, Number Theory, Carbondale 1979 (M. B. Nathanson, ed.), Lecture Notes in Math., vol. 751, Springer-Verlag, Berlin and New York, 1979, pp. 89-107. MR 564925 (81k:10089)
  • [2] Jia Xing-De, On an open combinatorial problem of Erdös and Nathanson, Chinese Ann. Math. (to appear).
  • [3] M. B. Nathanson, Simultaneous systems of representatives for families of finite sets, Proc. Amer. Math. Soc. (to appear). MR 955030 (90b:05002)

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DOI: https://doi.org/10.1090/S0002-9939-1988-0958037-4
Article copyright: © Copyright 1988 American Mathematical Society

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