P / NP problems

Exercise 1 Show that the following problems are in NP (a) We call two graphs G and H isomorphic if the nodes of G may be reordered so that it is identical to H. The problem is defined as follows. Iso ={(G,H)G and H are isomorphic graphs. } (b) A cut in a graph G=(V,E) is a separation of the vertices into two sets A and B such that AB=V. The size of a cut is the number of edges with one endpoint in A and one endpoint in B. The problem is defined as follows MAXCUT ={(G,k)G has a cut of size k or more. } (c) DOUBLE-SAT ={ has at least two satisfying assignments }