18506033
Evaluation of voting systems
T he recent spate of security issues and allegations of " lost votes " in the U.S. demonstrates the inadequacy of the standards used to evaluate our election systems. The current standards (the FEC Voting Systems Standards) along with the revision being developed by IEEE 1583 (see the article by Deutsch and Berger in last month's Communications) are poor from another perspective: they establish a single pass/fail threshold for all systems, thereby eliminating incentives for existing suppliers to improve their products and rendering the market unattractive to new entrants. Moreover, they fail to precisely define the properties that should be required of a voting system. Instead, the standards rely on specific designs that are more than 15 years old. These legacy designs handicap promising new approaches, such as the various voter-verified printing schemes. New systems are unnecessarily burdened, while their substantial advantages go unrecognized. A set of well-defined properties would encourage the development and commercialization of better voting systems, especially when combined with objective ways to measure performance with respect to those properties. The overall result would then resemble the quantitative federal ratings for automobiles , where features such as vehicle safety and fuel efficiency form a basis for Consumer Reports-style comparative tables. Similarly, specific performance rating guidelines for different aspects of voting systems would provide meaningful metrics upon which system developers could compete. Decision makers, both regulatory and purchasing, would then be free to establish their own minimums for these metrics. Such a rating system can thus cleanly disentangle the development of the technical evaluation process from the various political and regulatory processes. asked the technical community for assistance in determining a new standard. This community is no stranger to the area of voting system properties and standards: a number of authors have tried to characterize requirements , and, in 2002, the Workshop on Election Standards and Technology addressed similar issues. The performance properties for voting systems might include the following: integrity of the votes (both voter verification, " I can check that my vote was captured correctly " and public verification, " anyone can check that all recorded votes were counted correctly "); ballot secrecy (both voter privacy and resistance to vote selling and coercion); robustness (including resistance to denial of service attacks); usability and accuracy (including access for the disabled); and transparency (both of mechanism and election data). The inherent differences in system architectures can be characterized …
17285109
Concurrent operations on priority queues
Among the fastest priority queue implementations, skew heaps have properties that make them particularly suited to concurrent manipulation of shared queues. A concurrent version of the top down implementation of skew heaps can be produced from previously published sequential versions using almost mechanical transformations. This implementation requires O(log n) time to enqueue or dequeue an item, but it allows new operations to begin after only O(1) time on a MIMD machine. Thus, there is potential for significant concurrency when multiple processes share a queue. Applications to problems in graph theory and simulation are discussed in this article.
14456192
Improved interpretation of UNIX-like file names embedded in data
When the data processed by a program span several files, the common practice of including file names as data in some of the files leads to difficulties in moving or sharing that data. In systems using tree structured directories, this problem can be solved by making a syntactic distinction between absolute and relative file names.
44497725
Simulation of information flow in organizations
The Icarus simulation system is the result of an experiment in embedding small rule-based expert systems into a discrete event simulation environment. The goal of this work is to allow the use of expert systems to model the intelligent behavior of people that are included in the system being simulated. The major problems we have encountered in building the Icarus system have resulted from unexpected and fundamental interactions between expert systems and our discrete event simulation framework. These interactions are the focus of this paper.
44981587
A Tool for Inference Detection and Knowledge Discovery in Databases
Latent dependencies and relationships between groups of attributes in databases can produce inference channels that pose serious security threats. This paper uses a powerful knowledge discovery formalism for modeling and identifying latent inference channels in relational databases. The inference discovery methodology supports the analysis of precise and imprecise inference in database schemes and extensions. An interactive graphical tool for aiding inference discovery in Oracle databases is described. This tool is useful for identifying compromising inference channels in databases with many hidden dependencies.
31768671
Protein fold recognition
SummaryAn important, yet seemingly unattainable, goal in structural molecular biology is to be able to predict the native three-dimensional structure of a protein entirely from its amino acid sequence. Prediction methods based on rigorous energy calculations have not yet been successful, and best results have been obtained from homology modelling and statistical secondary structure prediction. Homology modelling is limited to cases where significant sequence similarity is shared between a protein of known structure and the unknown. Secondary structure prediction methods are not only unreliable, but also do not offer any obvious route to the full tertiary structure. Recently, methods have been developed whereby entire protein folds are recognized from sequence, even where little or no sequence similarity is shared between the proteins under consideration. In this paper we review the current methods, including our own, and in particular offer a historical background to their development. In addition, we also discuss the future of these methods and outline the developments under investigation in our laboratory.
9647930
Cross-layer adaptive video coding to reduce energy on general-purpose processors
Traditionally, video encoders have been designed assuming that the more redundancy is removed, the better the encoder. However, on current laptops, reducing the compression efficiency of the video encoder by reducing the number of instructions used to perform compression can actually reduce the total energy used to encode and transmit a sequence. The correct balance between computation and compression efficiency may change dynamically, motivating adaptive encoders. At the same time, recent general-purpose processors also employ energy-driven adaptations. For best gains, the adaptations in the hardware and application layers must be coordinated. From a system design viewpoint, this coordination must happen through minimal, well-defined interfaces. This paper develops (1) an adaptive video encoder for general-purpose processors that trades computational complexity for compression efficiency to minimize total system energy, and (2) a method for determining the best configuration for such an encoder when running on a processor that is also adaptive. Our adaptive processor employs recent energy saving techniques of dynamic voltage and frequency scaling and architectural adaptation. Using a detailed simulator, we show that our cross-layer adaptive application algorithm reduces energy significantly, when employed on a fixed or adaptive processor.
37553153
MultiGen: an integrated multiple-objective solution system
This paper presents an overview of a global multiple-objective system capable of rigourously handling a wide variety of multiple-objective and goal programming (GP) models. The system has two efficient solution engines that complement one another. These are an intelligent conventional optimisation system and a genetically driven heuristic search-based solver. The development of a linear and nonlinear sparse storage system capable of handling additional multiple-objective factors such as priority levels, goals, objectives, and upper and lower bounds is described. An appropriate input/output style for multiple-objective programmes is given. The resulting package provides an efficient and user-friendly environment for the interactive solution and analysis of a wide variety of multiple-objective programming (MOP) models.
11334584
The rapid generation of mutation data matrices from protein sequences
An efficient means for generating mutation data matrices from large numbers of protein sequences is presented here. By means of an approximate peptide-based sequence comparison algorithm, the set sequences are clustered at the 85% identity level. The closest relating pairs of sequences are aligned, and observed amino acid exchanges tallied in a matrix. The raw mutation frequency matrix is processed in a similar way to that described by Dayhoff et al. (1978), and so the resulting matrices may be easily used in current sequence analysis applications, in place of the standard mutation data matrices, which have not been updated for 13 years. The method is fast enough to process the entire SWISS-PROT databank in 20 h on a Sun SPARCstation 1, and is fast enough to generate a matrix from a specific family or class of proteins in minutes. Differences observed between our 250 PAM mutation data matrix and the matrix calculated by Dayhoff et al. are briefly discussed.