L(2,1)-coloring

L(2,1)-coloring is a specific type of graph coloring in the field of graph theory. It is a constraint on how vertices in a graph can be colored based on the distances between them. Specifically, a graph is said to be L(2,1)-colorable if it is possible to assign colors to its vertices such that: 1. If two vertices are adjacent (connected by an edge), they must receive different colors.