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1 MaxEnt is a program for modelling species distributions from presence-only species records. This 2 paper describes it from an ecological perspective, making explicit links between the structure of the 3 model, decisions required in producing a modelled distribution, and knowledge about the species 4 and the data that might affect those decisions. To begin(More)
We consider variants on the Prize Collecting Steiner Tree problem and on the primal-dual 2-approximation algorithm devised for it by Goemans and Williamson. We introduce an improved pruning rule for the algorithm that is slightly faster and provides solutions that are at least as good and typically signiicantly better. On a selection of real-world instances(More)
Virtually all research in scheduling theory has been concerned with clairvoyant scheduling where it is assumed that the characteristics of a job (in particular, its execution time, release time and dependence on other jobs) are known a priori. This assumption is invalid for scheduling problems that arise in time-sharing operating systems where the scheduler(More)
— When carrying Internet Protocol (IP) traffic over an Asynchronous Transfer Mode (ATM) network, the ATM adaptation layer must determine how long to hold a virtual circuit opened to carry an IP datagram. In this paper we present a formal statement of the problem and carry out a detailed empirical examination of various holding time policies taking into(More)
While few doubt that very high inflation is bad for growth, there is less agreement about the effects of moderate inflation. Using panel regressions and allowing for a nonlinear specification, this paper finds a statistically and economically significant negative relationship between inflation and growth, which holds robustly at all but the lowest inflation(More)
We consider the following NP optimization problem: Given a set of polynomials P i (x), i = 1 : : : s of degree at most 2 over GFp] in n variables, nd a root common to as many as possible of the polynomials P i (x). We prove that in the case when the polynomials do not contain any squares as monomials, it is always possible to approximate this problem within(More)
In this paper we consider the paging problem when the page request sequence is drawn from a distribution, and give an application to computer networking. In the IP-paging problem the page inter-request times are chosen according to independent distributions. For this model we construct a very simple deterministic algorithm whose page fault rate is at most 5(More)