Paulo Feofiloff

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The primal-dual scheme has been used to provide approximation algorithms for many problems. Goemans and Williamson gave a (2−1/(n−1))-approximation for the Prize-Collecting Steiner Tree Problem that runs in O(n3 logn) time—it applies the primaldual scheme once for each of the n vertices of the graph. We present a primal-dual algorithm that runs in O(n2(More)
The primal-dual scheme has been used to provide approximation algorithms for many problems. Goemans and Williamson gave a (2− 1 n−1 )-approximation for the Prize-Collecting Steiner Tree Problem that runs in O(n logn) time. Johnson, Minkoff and Phillips proposed a faster implementation of Goemans and Williamson’s algorithm. We give a proof that the(More)
A MILP model for an extended version of the Flexible Job Shop Scheduling problem is proposed. The extension allows the precedences between operations of a job to be given by an arbitrary directed acyclic graph rather than a linear order. The goal is the minimization of the makespan. Theoretical and practical advantages of the proposed model are discussed.(More)
A MILP model for an extended version of the Flexible Job Shop Scheduling problem is proposed. The extension allows the precedences between operations of a job to be given by an arbitrary directed acyclic graph rather than a linear order. The goal is the minimization of the makespan. Theoretical and practical advantages of the proposed model are discussed.(More)
Woodall’s conjecture asserts the following about every directed graph: if every directed cut of the graph has k or more edges then the graph has k or more mutually disjoint dijoins. Here, a dijoin is a set J of arcs such that any vertex is connected to any other by a path all of whose forward-directed arcs are in J . This talk is a little survey of the(More)
Woodall’s conjecture asserts the following about every directed graph: if every directed cut of the graph has k or more edges then the graph has k or more mutually disjoint dijoins. Here, a dijoin is a set J of arcs such that any vertex is connected to any other by a path all of whose forward-directed arcs are in J . This talk is a little survey of the(More)
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