Similar to congruence in geometry

So the same symbols are used.

The judgment of isomorphism is really troublesome.

A one-to-one mapping can be established between the vertex sets of two graphs,

Corresponding vertices maintain one-to-one correspondence of edges.

It can also be discussed through the adjacency matrix of graphs.

When the adjacency matrix of one graph is transformed into the adjacency matrix of another graph by exchanging rows or columns a finite number of times, the two graphs are isomorphic.