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
موضوعات مرتبط
مهندسی و علوم پایه ریاضیات ریاضیات گسسته و ترکیبات
پیش نمایش صفحه اول مقاله
The maximum size of intersecting and union families of sets
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
نویسندگان
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