This paper describes a new symmetry-based approach to solving a given ordinary di¬erence equation. By studying the local structure of the set of solutions, we derive a systematic method for determining one-parameter Lie groups of symmetries in closed form. Such groups can be used to achieve successive reductions of order. If there are enough symmetries, the di¬erence equation can be completely ...

Dynamic load balancing on hypercube multiprocessors is considered with emphasis on quantized loads. Quantized loads are divisible only in a xed size. First, we show that a direct application of the well-known Dimension Exchange Method(DEM) to quantized loads may result in di erence in assigned loads to processors as large as logN units after balancing for a hypercube of size N . Then we propose...

We analyze wireless communication systems employing multiple-transmit multiplereceive antennas in this thesis. Space-time codes have been proposed in the literature as an e cient means of coding over multiple transmit antennas. In particular, the rank and the determinant of code di erence matrices have been shown to be important in the design of space time codes in quasi-static fading channels....

This paper presents a study of the behavior of several di erence approximations for the incompressible Navier-Stokes equations as a function of the computational mesh resolution. In particular, the under-resolved case is considered. The methods considered include a Godunov projection method, a primitive variable ENO method, an upwind vorticity stream-function method, centered di erence methods ...

Recent years have witnessed a growing proportion of female general practitioners (GPs) worldwide. Because female GPs tend to work fewer hours than male GPs, this continuing trend may accelerate the shortage of GPs. This paper investigates the gender di erence in the wage elasticity of Australian GPs by maximum likelihood estimation of labour supply and wage equations. Quantitative information r...

An important concern in the design of search engines is the construction of an inv erted index. An inv erted index, also called a concordance, contains a list of documents (or posting list) for every possible search term. These posting lists are usually compressed with di erence coding. Di erence coding yields the best compression when the lists to be coded hav e high locality. Coding methods h...

Order of magnitude reasoning | reasoning by rough comparisons of the sizes of quantities | is often called \back of the envelope calculation", with the implication that the calculations are quick though approximate. This paper exhibits an interesting class of constraint sets in which order of magnitude reasoning is demonstrably fast. Speci cally, we present a polynomial-time algorithm that can ...

The results presented in this paper are part of a research project to investigate the possibilities to apply massively parallel architectures for numerical weather forecasting. Within numerical weather forecasting several numerical techniques are used to solve the model equations. This paper compares the performance of implementations on a MasPar system of two techniques, nite di erence and spe...

An important di erence in inductive bias between machine learning approaches is whether they assume the e ects of di erent properties on a target variable to be cumulative or not. We believe this di erence may have an important in uence on the performance of machine learning or data mining techniques, and hence should be taken into account when deciding which techniques to use. We illustrate th...

Finite-diierence approximations preserving the cosymmetry property for two-dimensional ltration convection problem are presented. Cosymmetry preserving discretizations connrm the predicted behavior of the family of equilibria and degeneration of the family is observed when an inappropriate approximation was used. 1 Planar Darcy convection problem and cosymmetry In recent years several discretiz...