need to answer(e)

1. Prove, disprove (give a counterexample, highlight the incorrectness or give the correct answer) or complete a proof. (d) Let tree T be the result of applying depth-first search to a connected graph. Then a non-root v of T is a cut-vertex if and only if v has a child w such that low(w) > dfnumber(v). (e) To apply the property of problem (d) or its refined version (if (d) is false and needs to be corrected) to identify the cut vertices of a graph, the most efficient algorithm requires invoking dfs twice, one for setting dfnumber and the other for setting low value and checking if the property holds