Permutation of any two rows or columns in an incidence matrix simply corresponds to relabelling the vertices and edges of the same graph. Conversely, two graphs X and Y are isomorphic if and only if their incidence matrices A(X) and A(Y) differ only by permutations of rows and columns.
Can someone explain me what does it mean, with an example. What exactly does "permutation of any two rows or columns" over hear means?