Let G = (V, E) be a graph with positive edge weights and let V’ c V. The min VI-cut prohlenl is to find a minimum weight set E’ E E such that no two nodes of V’ occur in the same component of G’ = (V, E\E’). Our main results are two new structural theorems for optimal solutions to the min V-cut problem when G is planar. The first theorem establishes for the first time a close connection between...

Absfmcf-We consider the real-weight maximum cut of a planar graph. Given an undirected planar graph with real-valued weights associated with its edges, find a partition of the vertices into two nonemply sets such that the sum of the weights of the edges connecting the two sets is maximum. The conventional maximum cut and minimum cut problems assume nonnegative edge weights, and thus are special...

An instance of the Connected Maximum Cut problem consists of an undirected graph G = (V,E) and the goal is to find a subset of vertices S ⊆ V that maximizes the number of edges in the cut δ(S) such that the induced graph G[S] is connected. We present the first non-trivial Ω( 1 logn ) approximation algorithm for the Connected Maximum Cut problem in general graphs using novel techniques. We then ...

We consider the Steiner k-cut problem which generalizes both the k-cut problem and the multiway cut problem. The Steiner k-cut problem is defined as follows. Given an edge-weighted undirected graph G = (V,E), a subset of vertices X ⊆ V called terminals, and an integer k ≤ |X|, the objective is to find a minimum weight set of edges whose removal results in k disconnected components, each of whic...

In this article we present the Hayastan Shakarian (HS), a robustness index for complex networks. HS measures the impact of a network disconnection (edge) while comparing the sizes of the remaining connected components. Strictly speaking, the Hayastan Shakarian index is defined as edge removal that produces the maximal inverse of the size of the largest connected component divided by the sum of ...

A subset F of edges in a connected graph G is a h-extra edge-cut if G − F is disconnected and every component has more than h vertices. The h-extra edge-connectivity λ(G) of G is defined as the minimum cardinality over all h-extra edge-cuts of G. A graph G, if λ(G) exists, is super-λ if every minimum h-extra edge-cut of G isolates at least one connected subgraph of order h + 1. The persistence ...

We introduce a new graph-theoretic approach to image segmentation based on minimizing a novel class of ‘mean cut’ cost functions. Minimizing these cost functions corresponds to finding a cut with minimummean edge weight in a connected planar graph. This approach has several advantages over prior approaches to image segmentation. First, it allows cuts with both open and closed boundaries. Second...