A coloring of a q-ary n-dimensional cube (hypercube) is called perfect if, for every n-tuple x, the collection of the colors of the neighbors of x depends only on the color of x. A Boolean-valued function is called correlation-immune of degree n − m if it takes value 1 the same number of times for each m-dimensional face of the hypercube. Let f = χ S be a characteristic function of a subset S o...

Given a perfect coloring of graph, we prove that the $L_1$ distance between two rows adjacency matrix graph is not less than corresponding parameter coloring. With help an algebraic approach, deduce corollaries this result for $2$-colorings, colorings in distance-$l$ graphs and distance-regular graphs. We also provide examples when obtained property reject several putative matrices infinite

Given a graphG = (V,E) and a set Lv of admissible colors for each vertex v ∈ V (termed the list at v), a list coloring of G is a (proper) vertex coloring φ : V → ⋃ v∈V Lv such that φ(v) ∈ Lv for all v ∈ V and φ(u) 6= φ(v) for all uv ∈ E. If such a φ exists, G is said to be list colorable. The choice number of G is the smallest natural number k for which G is list colorable whenever each list co...

A kernel of a directed graph D is defined as an independent set which is reachable from each outside vertex by an arc. A graph G is called kernel-solvable if an orientation D of G has a kernel whenever each clique of G has a kernel in D. The notion of kernel-solvability has important applications in combinatorics, list coloring, and game theory. It turns out that kernel-solvability is equivalen...

Consider the following total order: order the vertices by repeatedly removing a vertex of minimum degree in the subgraph of vertices not yet chosen and placing it after all the remaining vertices but before all the vertices already removed. For which graphs the greedy algorithm on this order gives an optimum vertex-coloring? Markossian, Gasparian and Reed introduced the class of -perfect graphs...

We study several cost coloring problems, where we are given a graph and a cost function on the independent sets and are to find a coloring that minimizes the function costs of the color classes. The “Rent-or-Buy” scheduling/coloring problem (RBC) is one that captures e.g., job scheduling situations involving resource constraints where one can either pay a full fixed price for a color class (rep...

We investigate the existence of perfect homogeneous sets for analytic colorings. An analytic coloring of X is an analytic subset of [X] , where N > 1 is a natural number. We define an absolute rank function on trees representing analytic colorings, which gives an upper bound for possible cardinalities of homogeneous sets and which decides whether there exists a perfect homogeneous set. We const...

Given a graphG = (V,E) and a set Lv of admissible colors for each vertex v ∈ V (termed the list at v), a list coloring of G is a (proper) vertex coloring φ : V → v∈V Lv such that φ(v) ∈ Lv for all v ∈ V and φ(u) 6= φ(v) for all uv ∈ E. If such a φ exists, G is said to be list colorable. The choice number of G is the smallest natural number k for which G is list colorable whenever each list cont...

A bull is a graph obtained by adding a pendant vertex at two vertices of a triangle. Here we present polynomial-time combinatorial algorithms for the optimal weighted coloring and weighted clique problems in bull-free perfect graphs. The algorithms are based on a structural analysis and decomposition of bull-free perfect graphs.

A graph G is trivially perfect if for every induced subgraph the cardinality of the largest set of pairwise nonadjacent vertices (the stability number) α(G) equals the number of (maximal) cliques m(G). We characterize the trivially perfect graphs in terms of vertex-coloring and we extend some definitions to infinite graphs.