We study algorithmic and structural aspects of connectivity in hypergraphs. Given a hypergraph H = (V, E) with n= |V |, m= |E| and p = ∑ e∈E |e| the fastest known algorithm to compute a global minimum cut in H runs in O(np) time for the uncapacitated case, and in O(np+ n2 log n) time for the capacitated case. We show the following new results. • Given an uncapacitated hypergraph H and an intege...

Minimum spanning tree is a minimum-cost spanning tree connecting the whole network, but it couldn't be directly obtained on uncertain graph. In this paper, we define the reliability as the existence probability of all minimum spanning trees and present an algorithm for evaluating reliability of the minimum spanning tree on uncertain graph. The time complexity of the algorithm is O(Nmn), where n...

We study the problems of finding a minimum cycle basis (a minimum weight set of cycles that form a basis for the cycle space) and a minimum homology basis (a minimum weight set of cycles that generates the 1-dimensional (Z2)-homology classes) of an undirected graph embedded on an orientable surface of genus g. The problems are closely related, because the minimum cycle basis of a graph contains...

Given n points in the plane, we study three optimization problems of computing an empty pseudo-triangle: we consider minimizing the perimeter, maximizing the area, and minimizing the longest maximal concave chain. We consider two versions of the problem: First, we assume that the three convex vertices of the pseudotriangle are given. Let n denote the number of points that lie inside the convex ...

We present eecient algorithms for nding rectilinear collision-free paths between two given points among a set of rectilinear obstacles. Our results improve the time complexity of previous results for nding the shortest rectilinear path, the minimum-bend shortest rectilinear path, the shortest minimum-bend rectilinear path and the minimum-cost rectilinear path. For nding the shortest rectilinear...

Consider the minimum s − t cut problem in an embedded undirected planar graph. Let p be the minimum number of faces that a curve from s to t passes through. If p = 1, that is, the vertices s and t are on the boundary of the same face, then the minimum cut can be found in O(n) time. For general planar graphs this cut can be found in O(n log n) time. We unify these results and give an O(n log p) ...

We study the following linear classification problem in signal processing: Given a set B of n black point and a set W of m white points in the plane (m = O(n)), compute a minimum number of lines L such that in the arrangement of L each face contain points with the same color (i.e., either all black points or all white points). We call this the Minimum Linear Classification (MLC) problem. We pro...

We show that an "-approximate solution of the cost-constrained K-commodity ow problem on an N-nodeM-arc network G can be computed by sequentially solving O K(" 2 + logK) logM log(" 1 K) single-commodity minimum-cost ow problems on the same network. In particular, an approximate minimumcost multicommodity ow can be computed in ~ O(" 2 KNM) running time, where the notation ~ O( ) means \up to log...

Let P be a set of n points in the plane and O be a set of k lines passing through the origin. We show: (1) How to compute the O-hull of P in Θ(n log n) time and O(n) space, (2) how to compute and maintain the rotated hull OHθ(P ) for θ ∈ [0, 2π) in O(kn log n) time and O(kn) space, and (3) how to compute in Θ(n log n) time and O(n) space a value of θ for which the rectilinear convex hull, RHθ(P...