On regular set systems containing regular subsystems

نویسندگان

چکیده

Let X,Y be finite sets, r,s,h,??N with s?r,X?Y. By ?Xh we mean the collection of all h-subsets X where each subset occurs ? times. A coloring (partition) is r-regular if element in exactly r subsets color. one-regular color class a perfect matching. We are interested necessary and sufficient conditions under which an can embedded into s-regular ?Yh. Using algebraic techniques involving glueing together orbits suitably chosen cyclic group, first author Newman solved case when ?=1,r=s,gcd(|X|,|Y|,h)=gcd(|Y|,h). purely combinatorial techniques, nearly settle h=4. It worth noting that completing partial symmetric latin squares closely related to ?=r=s=1,h=2 was by Cruse.

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ژورنال

عنوان ژورنال: European Journal of Combinatorics

سال: 2021

ISSN: ['1095-9971', '0195-6698']

DOI: https://doi.org/10.1016/j.ejc.2021.103393