Hi,

The definition of an isomorphism is a bijection between the sets of G and H

f: V(G) -> V(H)

such that any two vertices u and v of G are adjacent in G if and only if f(u) and f(v) are adjacent in H.

They following 3 functions are not isomorphisms but I need to provide one counterexample to the property above in each case.

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I am slightly confused here. Could someone please help me here.

Thanks in advance for any help.