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                * Princeton Discrete Math Seminar *
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Date: Thursday 19th March, 3:00 in Fine Hall 224.
 
Speaker: Alex Scott (Oxford)

Title: On a problem of Erdos and Moser

A set A of vertices in an r-uniform hypergraph H is ``covered'' in H 
if, for every (r−1)-set B contained in A, the set B+{u} is an edge of H. 
Erdos and Moser (1970) determined the minimum number of edges in a 
graph on n vertices such that every k-set is covered. We extend this 
result to r-uniform hypergraphs on sufficiently many vertices, and 
determine the extremal hypergraphs. We also address the problem for 
directed graphs.  Joint work with Bela Bollobas.

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Next week: TBA

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