Neighbor-locating coloring: graph operations and extremal cardinalities Carmen Hernando, Merc` e Mora, Ignacio M Pelayo 2 Dept. de Matem´aticas, Universitat Polit` ecnica de Catalunya, Barcelona, Spain Liliana Alc´on, Marisa Gutierrez 3 Centro de Matem´atica, Universidad Nacional de La Plata, La Plata, Argentina Abstract A k−coloring of a graph G =(V,E) is a k-partition Π = {S 1 ,...,S k } of V into independent sets, called colors. A k-coloring is called neighbor-locating if for ev- ery pair of vertices u, v belonging to the same color S i , the set of colors of the neighborhood of u is different from the set of colors of the neighborhood of v. The neighbor-locating chromatic number, χ NL (G), is the minimum cardinality of a neighbor-locating coloring of G. In this paper, we examine the neighbor-locating chromatic number for various graph operations: the join, the disjoint union and Cartesian product. We also characterize all connected graphs of order n ≥ 3 with neighbor-locating chromatic number equal either to n or to n − 1 and determine the neighbor-locating chromatic number of split graphs. Keywords: Coloring, location, neighbor-location, complete multipartite graph, join graph, split graph, disjoint union, Cartesian product.