Topology

S(S(f)) = S(f) for reloids ★★

Author(s): Porton

Question   $ S(S(f)) = S(f) $ for every endo-reloid $ f $?

Keywords: reloid

Posted by porton
updated May 8th, 2008
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Graph Theory » Basic G.T. » Matchings

Random stable roommates ★★

Author(s): Mertens

Conjecture   The probability that a random instance of the stable roommates problem on $ n \in 2{\mathbb N} $ people admits a solution is $ \Theta( n ^{-1/4} ) $.

Keywords: stable marriage; stable roommates

Posted by mdevos
updated February 26th, 2008
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Number Theory

Chowla's cosine problem ★★★

Author(s): Chowla

Problem   Let $ A \subseteq {\mathbb N} $ be a set of $ n $ positive integers and set \[m(A) = - \min_x \sum_{a \in A} \cos(ax).\] What is $ m(n) = \min_A m(A) $?

Keywords: circle; cosine polynomial

Posted by mdevos
updated February 22nd, 2008
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