# How to prove graph isomorphism is NP?

I know that Graph Isomorphism should be able to be verified in polynomial time but I don't really know how to approach the problem. Any help would be appreciated.

• What is graph isomorphism for you? Please add to your post a formal description. – Yuval Filmus Dec 2 '19 at 23:11

You haven't explained what graph isomorphism means for you, so let me assume that you mean the language of all pairs of graphs $$(G_1,G_2)$$ which are isomorphic.
Two graphs $$G_1 = (V_1,E_1),G_2 = (V_2,E_2)$$ are isomorphic if there exists a bijection $$f\colon V_1 \to V_2$$ such that $$(x,y) \in E_1$$ iff $$(f(x),f(y)) \in E_2$$.