کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
4653915 | 1632799 | 2012 | 11 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
The maximum size of intersecting and union families of sets
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موضوعات مرتبط
مهندسی و علوم پایه
ریاضیات
ریاضیات گسسته و ترکیبات
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چکیده انگلیسی
We consider the maximal size of families of kk-element subsets of an nn element set [n][n] that satisfy the properties that every rr subsets of the family have non-empty intersection, and no ℓℓ subsets contain [n][n] in their union. We show that for large enough nn, the largest such family is the trivial one of all (n−2k−1) subsets that contain a given element and do not contain another given element. Moreover we show that unless such a family is such that all subsets contain a given element, or all subsets miss a given element, then it has size at most .9(n−2k−1).We also obtain versions of these statements for weighted non-uniform families.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: European Journal of Combinatorics - Volume 33, Issue 2, February 2012, Pages 128–138
Journal: European Journal of Combinatorics - Volume 33, Issue 2, February 2012, Pages 128–138
نویسندگان
Mark Siggers, Norihide Tokushige,