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Capsule Reviews - The Capsule Reviews are intended to provide a short succinct review of each paper in the issue in order to bring to a wider readership. The Capsule Reviews were compiled by Fairouz Kamareddine. Professor Kamareddine is an Associate Editor of The Computer Journal and is based in the Department of Mathematical and Computer Sciences at Heriot-Watt University, Edinburgh, UK. ...

Reachability Analysis of Augmented Marked Graphs via Integer Linear Programming - Augmented marked graphs (AMGs) are extensions of marked graphs that allow resource sharing. It has been shown that AMGs are useful for modeling and analyzing certain types of flexible manufacturing systems (FMSs). To our knowledge, the techniques developed for analyzing AMGs are mostly based upon checking certain Petri net structures such as siphons. This article exploits the integer linear programming approach for the analysis of a subclass of ...

General Tree k-Coteries to Reduce the Degradation of Quorums - k-Coterie is a useful concept to solve the distributed k-mutual exclusion problem. The distributed k-mutual exclusion algorithms based on k-coteries have benefits of the high fault-tolerance and the low message cost. Harada and Yamashita proposed a basic tree structure to construct tree k-coteries. When the root fails, quorums are degraded and their sizes grow rapidly. In this paper, we propose the general tree structure to construct general tre...

Modeling DNA/RNA Strings Using Resistor--Capacitor (RC) Ladder Networks - A passive ladder circuit employing resistors and capacitors has been used to model single-stranded DNA/RNA strings. A detailed examination of the circuit's behavior has revealed that a significant number of correspondences may be established between the behavior of such circuits and the biological/chemical properties of DNA/RNA strings. Amino acid classifications such as aromatic/aliphatic, hydrophobic/hydrophilic, alpha-helix former, beta sheet...

Loopless Generation of Non-regular Trees with a Prescribed Branching Sequence - An ordered tree is called a non-regular tree with a prescribed branching sequence (or non-regular tree for short) if its internal nodes have a prespecified degree sequence in preorder list. We define a concise representation, called right distance sequences to describe such trees. A coding tree helps us to systematically investigate the structural representation of non-regular trees. Consequently, we present a loopless algorithm to generate Gray...

The Bipancycle-Connectivity and the m-Pancycle-Connectivity of the k-ary n-cube - The interconnection network considered in this paper is the k-ary n-cube that is an attractive variance of the well-known hypercube. Many interconnection networks that are desirable in both theoretical interests and practical systems, including the ring, torus and hypercube, may be regarded as the subclasses of k-ary n-cubes. In this paper, we investigate the pancycle-connected properties of the k-ary n-cube. We show that the k-ary n-cube is bip...

An Abstract Interpretation Approach for Enhancing the Java Bytecode Verifier - The Java virtual machine embodies a verifier that performs a set of checks on Java bytecode programs before their execution. The verifier carries out an efficient data-flow analysis applied to a type-level abstract interpretation of the code. The implementations of the bytecode verifier presented a significant problem with programs compiled with the Sun Java compiler (until version 1.4.1): there were legal Java programs which were correctly comp...

On the Usefulness of Fibonacci Compression Codes - Recent publications advocate the use of various variable length codes for which each codeword consists of an integral number of bytes in compression applications using large alphabets. This paper shows that another tradeoff with similar properties can be obtained by Fibonacci codes. These are fixed codeword sets, using binary representations of integers based on Fibonacci numbers of order m ≥ 2. Fibonacci codes have been used before, and this...

Fine-Grain Register Allocation and Instruction Scheduling in a Reference Flow - This paper proposes a new register allocation technique in which register allocation is performed at every reference of a variable. For each reference, the costs of various possible register allocations are estimated by tracing a possible instruction sequence. A cost model is formulated to reduce the scope of tracing. With an extension of the cost model to the estimation of instruction execution time, a new technique for the integration of instr...

Hierarchical Radiosity for Multiresolution Systems Based on Normal Tests - The hierarchical radiosity algorithm provides high-quality illumination and the view-independent results obtained can be re-employed for different camera positions. On the other hand, the utilization of multiresolution models is a common solution for the real-time rendering of complex scenes. In this case, the level of detail of each object depends on the specific camera position. Unfortunately, global illumination computations may present an im...

NIPSOM: Parallel Architecture and Implementation of a Growing SOM - This work describes a parallel implementation of a distinctly different concept in self-organizing maps (SOMs)—processing of the input as a whole, in parallel, via neurons attracted to cover regions of the input space rather than single input instances. The algorithm is analyzed from the perspective of its parallelism and a simple multi-machine concept is utilized to demonstrate the parallel nature of the neural network architecture. The n...

Multi-criteria Scheduling of Precedence Task Graphs on Heterogeneous Platforms - Latency, fault tolerance and reliability are important requirements for several applications that are time critical in nature: such applications require guarantees in terms of latency, even when processors are subject to failures. In this paper, we propose a fault-tolerant scheduling heuristic for mapping precedence task graphs on heterogeneous systems. Our approach is based on an active replication scheme, capable of supporting arbitrary fail-...

A Weighted Voting-Based Associative Classification Algorithm - A new associative classification algorithm based on weighted voting (ACWV) is presented. ACWV takes advantage of two methods: the optimal rule method preferring high-quality rules and the voting method considering the majority of the rules. Moreover, the method takes into account both the length and convictions of rules to calculate their weights. First, ACWV builds a class-count FP-tree (called CCFP-tree) from the given historical data. After t...

Resampling Halftone Images Using Interpolation and Error-Diffusion - Halftoning schemes are developed for reserving the quality after transforming continuous tone images to binary images under human vision, and are widely used in printing and outputting. Modern halftoning schemes focus on transforming forward and backward the two kinds of images, but basic operations for halftone images like rescaling, blurring and sharpening are still insufficient. In this paper, a novel halftone image resampling scheme based on...

Accelerating Multiple Sequence Alignment with the Cell BE Processor - The Cell Broadband Engine (BE) Architecture is a new heterogeneous multi-core architecture targeted at compute-intensive workloads. The architecture of the Cell BE has several features that are unique in high-performance general-purpose processors, most notably the extensive support for vectorization, scratch pad memories and explicit programming of direct memory accesses (DMAs) and mailbox communication. While these features strongly increase p...

Area-Feature Boundary Labeling - Boundary labeling is a relatively new labeling method. It can be useful in automating the production of technical drawings and medical drawings, where it is common to explain certain parts of the drawing with text labels, arranged on its boundary so that other parts of the drawing are not obscured. In boundary labeling, we are given a rectangle R which encloses a set of n sites. Each site s is associated with an axis-parallel rectangular label l...

A Case Study Using a Methodological Approach to Developing User Interfaces for Elderly and Disabled People - In this paper, we present a case study on the development of interfaces for elderly and disabled users. The domain of the case study was situated in the home environment, where we focused on producing affordable technologies to enable users to interact with and to control home appliances. We have developed ambient user interfaces that are integrated in familiar home artefacts, such as televisions and digital picture frames. These interfaces are ...

Turning Back Time--What Impact on Performance? - Consistent with the divide-and-conquer approach to problem solving, a recursive result is presented in the domain of stochastic modelling that derives product-form solutions for the steady state probabilities of certain networks composed from interacting Markov chains. Practical applications include multi-tasking operating systems, communication channels and multi-tiered storage systems. The approach is also applied to the computation of respons...

Program Analysis Probably Counts - Semantics-based program analysis uses an abstract semantics of programs/systems to statically determine run-time properties. Classic examples from compiler technology include analyses to support constant propagation and constant folding transformations and estimation of pointer values to prevent buffer overruns. More recent examples include the estimation of information flows (to enforce security constraints) and estimation of non-functional pro...

DNA Profiles Link Dope to Its Source - 09 Jul 03 Forensic scientists in the U.S. are applying DNA fingerprinting methods to the cannabis plant. They say the technique, which is being used to create a database of DNA profiles of different marijuana plants, will help them to trace the source of any sample. 'It links everybody together: the user, the distributor, the grower,' says the database's creator, Heather Miller Coyle of the Connecticut State Forensic Science Laboratory in Meriden...

Mathematics: Does the Proof Stack Up? - by George Szpiro 03 Jul 03 Just under five years ago, Thomas Hales made a startling claim. In an e-mail he sent to dozens of mathematicians, Hales declared that he had used a series of computers to prove an idea that has evaded certain confirmation for 400 years. The subject of his message was Kepler's conjecture, proposed by the German astronomer Johannes Kepler, which states that the densest arrangement of spheres is one in which they are stack...

Scientists Discover Planetary System Similar to Our Own - The image shows an impression by David A. Hardy of a possible scene from a moon orbiting the extra-solar planet in orbit around the star HD70642. Photo Credit: David A. Hardy. ...

Hacker How-To Good Summer Reading - by Michelle Delio 27 Jun 03 Stealing the Network: How to Own the Boxby Ryan RussellSyngress, 330 pp., $49.95 Stealing The Network: How to Own the Box, a compendium of tales written by well-known hackers, is a perfect summer read. The stories are fictional. The technology and techniques described are very real. A warning: Those...