Let G be a weighted connected undirected graph with distinct positive edge weights. If every edge weight is increased by the same value, then which of the following statements is/are TRUE? P: Minimum spanning tree of G does not change Q: Shortest path between any pair of vertices does not change

Let G be a weighted connected undirected graph with distinct positive edge weights. If every edge weight is increased by the same value, then which of the following statements is/are TRUE? P: Minimum spanning tree of G does not change Q: Shortest path between any pair of vertices does not change Correct Answer P only

Concept:

A minimum spanning tree (MST) or minimum weight spanning tree is a subset of the edges(V – 1 ) of a connected, edge-weighted undirected graph G(V, E) that connects all the vertices together, without any cycles and with the minimum possible total edge weight.

Example:

Graph G(V, E)

[ alt="F1 R.S Madhu 20.12.19 D1" src="//storage.googleapis.com/tb-img/production/19/12/F1_R.S_Madhu_20.12.19_D1.png" style="width: 154px; height: 126px;">

Shortest path between A and C = A → B and B → C, that is,1 + 2 = 3

G(V, V – 1) → minimum spanning tree

[ alt="F1 R.S Madhu 20.12.19 D3" src="//storage.googleapis.com/tb-img/production/19/12/F1_R.S_Madhu_20.12.19_D3.png" style="width: 154px; height: 125px;">

Increase the weight of G(V, E) by 10

Graph G'(V, E)

[ alt="F1 R.S Madhu 20.12.19 D2" src="//storage.googleapis.com/tb-img/production/19/12/F1_R.S_Madhu_20.12.19_D2.png" style="width: 154px; height: 125px;">

Shortest path between A and C = A → C = 20 (different path)

G'(V, V – 1) → minimum spanning tree

[ alt="F1 R.S Madhu 20.12.19 D4" src="//storage.googleapis.com/tb-img/production/19/12/F1_R.S_Madhu_20.12.19_D4.png" style="width: 154px; height: 126px;">

 

Statement P: TRUE

Minimum spanning the tree of G does not change

Statement Q: False

Shortest path between any pair of vertices may change

Related Questions

Let G be an undirected connected graph with distinct edge weights . Let emax be the edge with maximum weight and emin be the edge with minimum weight. Which of the following statements is false.
Let G be an undirected connected graph with distinct edge weight. Let emax be the edge maximum weight and emin the edge with minimum weight. Which of the following statements are false?
Consider a simple undirected weighted graph G, all of whose edge weights are distinct. Which of the following statements about the minimum spanning trees of G is/are TRUE ?