Question

What is a chromatic index?

(a) The maximum number of colors required for proper edge coloring of graph

(b) The maximum number of colors required for proper vertex coloring of graph

(c) The minimum number of colors required for proper vertex coloring of graph

(d) The minimum number of colors required for proper edge coloring of graph

This question was posed to me in a national level competition.

The query is from Graph Coloring in section Graph Coloring of Data Structures & Algorithms II

Answer 1

The correct choice is (d) The minimum number of colors required for proper edge coloring of graph

Explanation: The minimum number of colors required for proper edge coloring of graph is called chromatic index whereas the minimum number of colors required for proper vertex coloring of graph is called chromatic number of a graph.