I have a collection of 4 graphs, each with 7 vertices [see figure]. I have to determine if the last 3 of them are isomorphic to the first one.
What I have tried so far:
- looking at the degree list of each graph. However, all of them have the same unordered degree list. But from what I understand, that is not conclusive evidence of isomorphism in itself.
- creating an adjacency matrix. The problem is that it's several 7 x 7 matrices, and then I have to find the permutation and transpose and dot product and string representation and canonical values of them...it's a long procedure and I have limited time in the exam.
So I was wondering if there's something I'm missing. Is there a quick way to tell if these are isomorphic?