Graph Theory

Hitting every large maximal clique with a stable set ★★

Author(s): King; Rabern

Conjecture   There is a universal constant $ \epsilon>0 $ such that every graph contains a stable set which intersects every maximal clique of size $ (1-\epsilon)(\Delta+1) $.

Conjecture   Every graph contains a stable set which intersects every maximal clique of size $ >\frac{2}{3}(\Delta+1) $.

Keywords: independent set; maximal clique

Posted by Andrew King
updated March 31st, 2011
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Graph Theory » Extremal G.T.

Extremal problem on the number of tree endomorphism ★★

Author(s): Zhicong Lin

Conjecture   An endomorphism of a graph is a mapping on the vertex set of the graph which preserves edges. Among all the $ n $ vertices' trees, the star with $ n $ vertices has the most endomorphisms, while the path with $ n $ vertices has the least endomorphisms.

Keywords:

Posted by shudeshijie
updated November 25th, 2020
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Group Theory

Which lattices occur as intervals in subgroup lattices of finite groups? ★★★★

Author(s):

Conjecture  

There exists a finite lattice that is not an interval in the subgroup lattice of a finite group.

Keywords: congruence lattice; finite groups

Posted by williamdemeo
updated February 22nd, 2011
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