Given a complete graph G = (V,E) with a length function on edges and a subset R of V, the terminal Steiner tree is defined to be a Steiner tree in G with all the vertices of R as its leaves. Then the terminal Steiner tree problem is to find a terminal Steiner tree in G with minimum length. In this paper, we present an approximation algorithm with performance ratio 2ρ - (ρα2 - αρ)/(α+α2)(ρ-1)+2(α-1)2 for the terminal Steiner tree problem, where ρ is the best-known performance ratio for the Steiner tree problem with any α ≥ 2. When we let α = 3.87 ≈ 4, this result improves the previous performance ratio of 2.515 to 2.458.
關聯:
Computational Science and Its Applications - ICCSA 2011 Volume 6784/2011 P.141-151