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The question is to show that the recognition version of Clique is in NP.

I have started with a graph G=(V,E) and integer k such that G does have a clique C of cardinality k. How to proceed further from here?

Thanks in advance for any help.

deial
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    Because of the capital letters, it took me some time to understand that this is not about the recognition by the mathematical community of a guy called Max Clique who claimed to have solved the P=NP problem... – Nikolaj-K Mar 25 '13 at 09:00

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The idea is that given a set $C$ of vertices, you can check in polynomial time whether $C$ is a clique of cardinality $k$.

Robert Israel
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  • Isn't this only half of the problem though? How would I give an evidence of the nonexistence of a $k$-clique that can be checked in polynomial time? – hardmath Dec 30 '16 at 02:13
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    @hardmath NP means that a "yes" answer can be checked in polynomial time. If a "no" answer can be checked in polynomial time, the problem is in co-NP. – Robert Israel Dec 30 '16 at 02:29
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Why don't you even try to find the solution in wikipedia? http://en.wikipedia.org/wiki/Clique_problem#NP-completeness

gukoff
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