This paper presents an algorithm to obtain near optimal solutions for the Steiner tree problem in graphs. It is based on a Lagrangian relaxation of a multi-commodity flow formulation of the problem.â€¦ (More)

A binary matrix has the Consecutive Ones Property (CIP) when there is a permutation of its rows that leaves the 1â€™s consecutive in every column. We study the recognition problem for these matrices,â€¦ (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 graphâ€¦ (More)

A bull is a graph obtained by adding a pendant vertex at two vertices of a triangle. A graph is perfectly orderable if it admits an ordering such that the greedy sequential method applied on thisâ€¦ (More)

Petrobras produces nearly 90 percent of Brazilâ€™s oil at about 80 offshore oil platforms. It transports approximately 1,900 employees daily between these platforms and four mainland bases, using moreâ€¦ (More)