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Problems(1)

All 16 members of F have exactly one element in common

Source:

9/15/2010
Let KK denote the set {a,b,c,d,e}\{a, b, c, d, e\}. FF is a collection of 1616 different subsets of KK, and it is known that any three members of FF have at least one element in common. Show that all 1616 members of FF have exactly one element in common.
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