The minimum 0-extension problem 0-Ext[Γ ] on a graph Γ is: given a set V including the vertex set VΓ of Γ and a nonnegative cost function c defined on the set of all pairs of V , find a 0-extension d of the path metric dΓ of Γ with ∑ xy c(xy)d(x, y) minimum, where a 0-extension is a metric d on V such that the restriction of d to VΓ coincides with dΓ and… (More)