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Set Systems with L‐Intersections and k‐Wise L‐Intersecting Families
Authors:Shuchao Li  Huihui Zhang
Institution:Faculty of Mathematics and Statistics, Central China Normal University, P.R. China
Abstract:In this paper, by employing linear algebra methods we obtain the following main results:
  • (i) Let urn:x-wiley:10638539:media:jcd21524:jcd21524-math-0001 and urn:x-wiley:10638539:media:jcd21524:jcd21524-math-0002 be two disjoint subsets of urn:x-wiley:10638539:media:jcd21524:jcd21524-math-0003 such that urn:x-wiley:10638539:media:jcd21524:jcd21524-math-0004 Suppose that urn:x-wiley:10638539:media:jcd21524:jcd21524-math-0005 is a family of subsets of urn:x-wiley:10638539:media:jcd21524:jcd21524-math-0006 such that urn:x-wiley:10638539:media:jcd21524:jcd21524-math-0007 for every pair urn:x-wiley:10638539:media:jcd21524:jcd21524-math-0008 and urn:x-wiley:10638539:media:jcd21524:jcd21524-math-0009 for every i. Then urn:x-wiley:10638539:media:jcd21524:jcd21524-math-0010 Furthermore, we extend this theorem to k‐wise L‐intersecting and obtain the corresponding result on two cross L‐intersecting families. These results show that Snevily's conjectures proposed by Snevily (2003) are true under some restricted conditions. This result also gets an improvement of a theorem of Liu and Hwang (2013).
  • (ii) Let p be a prime and let urn:x-wiley:10638539:media:jcd21524:jcd21524-math-0011 and urn:x-wiley:10638539:media:jcd21524:jcd21524-math-0012 be two subsets of urn:x-wiley:10638539:media:jcd21524:jcd21524-math-0013 such that urn:x-wiley:10638539:media:jcd21524:jcd21524-math-0014 or urn:x-wiley:10638539:media:jcd21524:jcd21524-math-0015 and urn:x-wiley:10638539:media:jcd21524:jcd21524-math-0016 Suppose that urn:x-wiley:10638539:media:jcd21524:jcd21524-math-0017 is a family of subsets of n] such that (1) urn:x-wiley:10638539:media:jcd21524:jcd21524-math-0018 for every pair urn:x-wiley:10638539:media:jcd21524:jcd21524-math-0019 (2) urn:x-wiley:10638539:media:jcd21524:jcd21524-math-0020 for every i. Then urn:x-wiley:10638539:media:jcd21524:jcd21524-math-0021 This result improves the existing upper bound substantially.
Keywords:Erdő  s‐Ko‐Rado theorem  Snevily's conjecture  k‐wise L‐intersecting  difference sizes  05D05  11F75  11B05
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