xie ≥ 0 ∀i,∀e The sets δ+(v) and δ−(v) correspond to the incoming and outgoing flow, respectively, for vertex v. The summation constraints then enforce flow conservation, and source/sink assignments. Since the objective function is to minimize t, which is constrained to be an upper bound for the flow across any edge, t will give us the (possibly fractional) congestion for a solution point of th...

The publish/subscribe (pub/sub) paradigm provides content-oriented data dissemination, where communication channels between content providers and content consumers are set up on the basis of interest matches between content provided by the publishers and content requested by the subscribers. In this paper, we study a distributed matchmaker system which resides on the data dissemination path, in...

Given a discrete eight-connected curve, it can be represented by discrete eight connected segments. In this paper, we try to determine the minimal number of necessary discrete segments. This problem is known as the min DSS problem. We propose to use a generic curve representation by discrete tangents, called a tangential cover which can be computed in linear-time. We introduce a series of crite...

Workforce scheduling problems are typical constraint satisfaction problems in which different constraints must be fulfilled, like needed workforce per day, forbidden sequences of shifts, length of work and days-off blocks etc. There are two main variants of workforce schedules: rotating (or cyclic) workforce schedules and non-cyclic workforce schedules. In a rotating workforce schedule all empl...

We study the hardness of approximation for the MINIMUM HACKING problem, which roughly can be described as the problem of finding the best way to compromise some target nodes given a few initial compromised nodes in a network. We give three reductions to show that MINIMUM HACKING is not approximable to within where , for any ! " $#% . In particular, the reductions are from a PCP, from the MINIMU...