In an undirected graph G = (V, E) with a weight function w : E × V → Q + , the weighted degree d w (v; E) of a vertex v is defined as {w(e, v) | e ∈ E incident with v}. In this paper, we consider a network design problem with upper-bound on weighted degree of each vertex. Inputs of the problem are an undirected graph G = (V, E) with E = E 1∪ E 2∪ E 3 , weights w 1 :skew supermodular set function f : 2 V → N, and a degree-bound b : A → Q + . A solution consists of F ⊆ E, and weights w i :It is defined to be feasible if the cut-size of U in (V, F ) is at least f (U ) for U ⊂ V , w 2 (e, u) + w 2 (e, v) = µ(e) for e = uv ∈ F 2 , {w 3 (e, u), w 3 (e, v)} = {0, ν(e)} for e = uv ∈ F 3 , and d w1 (v;
The goal of this problem is to find a feasible solution that minimizes its cost e∈F c(e).Relaxing the constraints on weighted degree, we propose a bi-criteria approximation algorithm based on the iterative rounding, which has been successfully applied to the degreebounded spanning tree problem. Our algorithm computes a (2, 9 + 5θ)-approximate solution, where θ = max{b(u)/b(v), b(v)/b(u) | uv ∈ E 2 } if E 2 = ∅ and θ = 0 if E 2 = ∅, where (α, β)-approximate solution has the cost at most α times the optimal and the weighted degree of v at most βb(v). We also give a (1, 5 + 3θ)-approximation algorithm to the case of f (U ) = 1 for U ⊂ V . Moreover, a problem minimizing the maximum weighted degree of vertices is also discussed.