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Topic: Graphs with two-coloured vertices
Replies: 1   Last Post: Sep 23, 2011 10:30 AM

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Ivo Siekmann

Posts: 4
Registered: 6/7/09
Graphs with two-coloured vertices
Posted: Aug 19, 2011 5:30 AM
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I am interested in the number of all graphs whose vertices are coloured
in two colours (I would like to know the number of all improper
colourings, not the number of bi-coloured graphs, see below).

The problem can be solved in special cases (provided that the
automorphism group is known) by applying Polya's theorem. Also, the
number of bi-coloured graphs (where vertices of the same colour must not
be adjacent) is known (Harary, 1958).

I am particularly interested in connected graphs, but I would also be
very happy about anything on trees.

Thanks a lot!
Ivo




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