Last Updated : 20 Dec, 2018

Which of the following option is incorrect regarding minimum spanning tree?
(A) In an adjacency matrix for an undirected graph with 5 nodes. If all diagonal element is 0 and all non-diagonal element is 1 then there will be multiple distinct MST of cost 4.
(B) In an undirected graph G with distinct edge weight if emax is the edge with maximum weight and emin is the edge with minimum weight then no minimum spanning tree contain emax.
(C) In an undirected graph G with distinct edge weight if emax is the edge with maximum weight and emin is the edge with minimum weight. If emax is in a minimum spanning tree, then its removal must disconnect G.
(D) In a weighted undirected graph with distinct edges, if every edge weight is increased by same weight then minimum spanning tree does not changed.


Answer: (B)

Explanation: In an undirected graph G with distinct edge weight if emax is the edge with maximum weight and emin is the edge with minimum weight then G has unique minimum spanning tree, If emax is in a minimum spanning tree, then its removal must disconnect G, every minimum spanning tree of G must contain emin but its not necessary that no minimum spanning tree contains emax.
So, option (B) is correct.

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