K(m,n) refers to the Kneser graph, a type of graph in mathematics that is used in combinatorial topology and graph theory. In this graph, the vertices represent the m-element subsets of an n-element set. An edge connects two vertices if the corresponding subsets are disjoint, meaning they share no common elements. The Kneser graph K(m,n) is denoted by two parameters, m and n, where n must be greater than or equal to 2m. These graphs have interesting properties and applications, including connections to topological spaces and combinatorial designs. They are also studied in the context of coloring problems and graph theory.