We consider the problem of finding a minimum cost 0 − 1 submodular flow with the additional constraint that the sum of the incoming and outgoing flow at each node cannot exceed a given limit. We show that this problem is NP-hard, but it can be approximated in the following sense: we can find a submodular flow of cost not greater than the optimum which violates the additional constraints by at m...

This paper presents a new elastic time algorithm for adjusting hypermedia document presentation in order to avoid temporal inconsistencies. The algorithm explores the flexibility offered by some hypermedia models in the definition of media object duration and uses this flexibility for choosing the objects to be stretched or shrunk in such a way that the best possible quality of presentation is ...

Joint ground states of two directed polymers in a random medium are investigated. Using exact min-cost flow optimization the true two-line ground-state is compared with the single line ground state plus its first excited state. It is found that these two-line configurations are (for almost all disorder configurations) distinct implying that the true two-line ground-state is non-separable, even ...

We study the question of fair clustering under the disparate impact doctrine, where each protected class must have approximately equal representation in every cluster. We formulate the fair clustering problem under both the k-center and the k-median objectives, and show that even with two protected classes the problem is challenging, as the optimum solution can violate common conventions—for in...

The single-sink fixed-charge transportation problem (SSFCTP) consists in finding a minimum cost flow from a number of supplier nodes to a single demand node. Shipping costs comprise costs proportional to the amount shipped as well as a fixed charge. Although the SSFCTP is an important special case of the well known fixed-charge transportation problem, only a few methods for solving this problem...

Consider a planar graph G = (V,E) with polynomially bounded edge weight function w : E → [0, poly(n)]. The main results of this paper are NC algorithms for the following problems: • minimum weight perfect matching in G, • maximum cardinality and maximum weight matching in G when G is bipartite, • maximum multiple-source multiple-sink flow in G where c : E → [1, poly(n)] is a polynomially bounde...

A critical issue in the design of routing protocols for wireless sensor networks is the efficient utilization of resources such as scarce bandwidth and limited energy supply. Many routing schemes proposed in the literature try to minimize the energy consumed in routing or maximize the lifetime of the sensor network without taking into consideration limited capacity of wireless links. This can l...

The DNA fragment assembly is an essential step in DNA sequencing projects. Since DNA sequencers output fragments, the original genome must be reconstructed from these small reads. In this paper, a new fragment assembly algorithm, Pattern Matching based String Graph Assembler (PMSGA), is presented. The algorithm uses multipattern matching to detect overlaps and a minimum cost flow algorithm to d...

We present a new model for a strategic locomotive scheduling problem arising at the Deutsche Bahn AG. The model is based on a multi-commodity min-cost flow formulation that is also used for public bus scheduling problems. However, several new aspects have to be additionally taken into account, such as cyclic departures of the trains, time windows on starting and arrival times, network-load depe...

We describe an O(nh min{log U, n log n}) capacity scaling algorithm for the minimum cost submodular flow problem. Our algorithm modifies and extends the Edmonds–Karp capacity scaling algorithm for minimum cost flow to solve the minimum cost submodular flow problem. The modification entails scaling a relaxation parameter δ. Capacities are relaxed by attaching a complete directed graph with unifo...