I have an intuition that topo-sort of an original graph
A -> B -> C D -> B
topo-sort is [D, A, B, C] or [A, D, B, C]
If I transpose the graph
C -> B -> A B -> D
the postordering dfs of this transposed graph also gives [D, A, B, C] or [A, D, B, C]
Please, I can't mathematically prove/disprove it. If not true, an counter example would helpful.
A postordering is a list of the vertices in the order that they were last visited by the algorithm