The statement to prove:- A graph in which every node has degree at most k can be colored with k+1 colors Obviously k >= 0  => k+1 >= 1 [degree cannot be negative]  Proof by induction on number of vertices n:-  Base Case:- when n = 1, then the graph with single vetex can be colored with 1 color. SInce degree of single vertex must be 0 , k+1 >= 1. Hence the statement holds for graph with 1 vertex Induction Hypothesis:- Assume that for all graphs G with n vertices such that degree of each vertex is at most k, G can be colored with at most k+1 colors. Induction step:- Consider a graph G' with n+1 vertices such that degree of any vertex v ... See the full answer