Subject: Questions related to NP-complete problem

5. GRAPH 3-COLOURABILITY
instance:  graph G=(V,E)
question : is G 3-colorable, that is, does there exist a function 
f:V-->{1,2,3} such that f(u)=f(v)  whenever {u,v} belongs to E.
i am a student of Computers ..trying to under stand NP completeness.
--------------------------------------------------------------------
Part 2:

related to NP-complete prob . partition of sets : 

4.SET SPLITTING.
 instance: collection c of subsets of finite  set S.
 question: is there a partition of s into 2 subsets S1 & S2, such that no 
subset in C is entirely cantained in either S1 or S2.

Re: Questions related to NP-complete problem