WH Lin, GJ Chang - Discrete applied mathematics, 2010 - Elsevier
For a positive integer k, a graph G is equitably k-colorable if there is a mapping f: V (G)→{1,
2,…, k} such that f (x)≠ f (y) whenever xy∈ E (G) and|| f− 1 (i)|−| f− 1 (j)||≤ 1 for 1≤ i< j≤ k …