Cláudia Linhares Sales

Learn More
Two non-adjacent vertices x and y in a graph G form an even pair if every induced path between them has an even number of edges. For a given pair fx; yg in a graph G, we denote by G xy the graph obtained from G by contracting x and y. In 1982, Fonlupt and Uhry proved that if G is perfect then so is G xy. In 1987, Meyniel used this fact to prove that no(More)
The Grundy number of a graph G is the largest k such that G has a greedy k-coloring, that is, a coloring with k colors obtained by applying the greedy algorithm according to some ordering of the vertices of G. In this article, we give new bounds on the Grundy number of the product of two graphs. 2011 Wiley Periodicals, Inc. J Graph Theory
In this article, we define a new class of graphs, the fat-extended P4-laden graphs, and we show a polynomial time algorithm to determine the Grundy number of the graphs in this class. This result implies that the Grundy number can be found in polynomial time for any graph of the following classes: P4-reducible, extended P4-reducible, P4-sparse, extended(More)
Let f(k) be the smallest integer such that every f(k)-chromatic digraph contains every oriented tree of order k. Burr proved that f(k) ≤ (k−1) and conjectured f(k) = 2n−2. In this paper, we give some sufficient conditions for an n-chromatic digraphs to contains some oriented tree. In particular, we show that every acyclic n-chromatic digraph contains every(More)
In this paper, we consider a new edge coloring problem to model call scheduling optimization issues in wireless mesh networks: the proportional coloring. It consists in finding a minimum cost edge coloring of a graph which preserves the proportion given by the weights associated to each of its edges. We show that deciding if a weighted graph admits a(More)
Rapid diagnosis of Mycobacterium tuberculosis remains an obstacle for therapy of tuberculosis (TB). Adenosine deaminase isoform 2 (ADA2) is produced by activated macrophages and has been used for diagnosis of TB from extra-pulmonary sites. However, few studies adequately address whether serum ADA2 activity is useful for diagnosis of active pulmonary(More)
A coloring c of a graph G = (V,E) is a b-coloring if in every color class there is a vertex colored i whose neighborhood intersects every other color classes. The b-chromatic number of G, denoted χb(G), is the greatest integer k such that G admits a b-coloring with k colors. A graph G is tight if it has exactly m(G) vertices of degree m(G)−1, where m(G) is(More)
A b-coloring is a coloring of the vertices of a graph such that each color class contains a vertex that has a neighbor in all other color classes. The b-chromatic number of a graph G is the largest integer k such that G admits a b-coloring with k colors. A graph is b-perfect if the b-chromatic number is equal to the chromatic number for every induced(More)