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Recently, Byrka, Grandoni, RothvoBand Sanita gave a 1.39 approximation for the Steiner tree problem, using a hypergraph-based linear programming relaxation. They also upper-bounded its integrality gap by 1.55. We describe a shorter proof of the same integrality gap bound, by applying some of their techniques to a randomized loss-contracting algorithm. (C) 2010 Elsevier B.V. All rights reserved.
Jean-Yves Le Boudec, Milan Vojnovic