bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Modified Approach to the Doplicher/Roberts Theorem on the Construction of the Field Algebra and the Symmetry Group in Superselection Theory
Authors: Baumgärtel H. 
Published: July 2002

Let [Formula: see text] be a unital C*-algebra with trivial center [Formula: see text]. Let [Formula: see text] denote a tensorial category of unital endomorphisms of [Formula: see text] equipped with several properties to be explained in the text. Doplicher and Roberts have shown, among other things, that there is a C*-algebra [Formula: see text] and a compact group [Formula: see text] of automorphisms of ℱ such that ℱ is a Hilbert C*-system over [Formula: see text] w.r.t. [Formula: see text], where [Formula: see text] is the fixed point algebra w.r.t. [Formula: see text], [Formula: see text] and the objects [Formula: see text] are characterized as the canonical endomorphisms of certain algebraic [Formula: see text]-invariant Hilbert spaces ℋρ⊂ℱ, see Doplicher/Roberts [1, 2, 3]. The starting point of the approach presented in this paper to point out the mentioned result is an [Formula: see text]-leftmodule ℱ0:={∑ρ,jAρ,jΦρ,j}. ρ runs through a full system of irreducible and mutually disjoint objects of [Formula: see text], j=1,2,…,d(ρ), where d(ρ) denotes the statistical dimension of [Formula: see text] is an orthonormal basis of a d(ρ)-dimensional Hilbert space. The system {Φρj}ρj forms a leftmodule basis of ℱ0, the coefficients Aρj are members of [Formula: see text]. The strategy is to equip successively ℱ0 with a bimodule structure, a product and a *-structure and finally with a C*-norm ||.||*. The symmetry group [Formula: see text] appears as the group of all automorphisms of the *-algebra ℱ0 leaving the [Formula: see text]-scalar product [Formula: see text] invariant, where F=∑ρ,jAρjΦρj, G=∑ρ,jBρjΦρj. The field algebra is then given by ℱ:= clo ||.||*ℱ0.
A CLOSURE OPERATION IN RINGS
Authors: ARA PERE , PEDERSEN GERT K. , PERERA FRANCESC 
Published: July 2002

We study the operation E → cl (E) defined on subsets E of a unital ring R, where x ∈ cl (E) if (x + Rb) ∩ E ≠ ∅ for each b in R such that Rx + Rb = R. This operation, which strongly resembles a closure, originates in algebraic K-theory. For any left ideal L we show that cl (L) equals the intersection of the maximal left ideals of R containing L. Moreover, cl (Re) = Re + rad (R) if e is an idempotent in R, and cl (I) = I for a two-sided ideal I precisely when I is semi-primitive in R (i.e. rad (R/I) = 0). We then explore a special class of von Neumann regular elements in R, called persistently regular and characterized by forming an "open" subset Rpr in R, i.e. cl (R\Rpr) = R\Rpr. In fact, R\Rpr = cl (R\Rr), so that Rpr is the "algebraic interior" of the set Rr of regular elements. We show that a regular element x with partial inverse y is persistently regular, if and only if the skew corner (1 - xy)R(1 - yx) is contained in Rr. If I reg (R) denotes the maximal regular ideal in R and [Formula: see text] the set of quasi-invertible elements, defined and studied in [4], we prove that [Formula: see text]. Specializing to C*-algebras we prove that cl (E) coincides with the norm closure of E, when E is one of the five interesting sets R-1, [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text], and that Rpr coincides with the topological interior of Rr. We also show that the operation cl respects boundedness, self-adjointness and positivity.
CHARGE ORDER TRANSITION IN LiMn2O4
Authors: PAOLONE A. , CANTELLI R. , ROUSSE G. , MASQUELIER C. , FERRETTI M. 
Published: July 2002

Stoichiometric LiMn2O4 undergoes a structural phase transition around room temperature from cubic to orthorhombic, induced by a partial charge ordering on the manganese sites, similar to the Verwey transition occurring in Fe3O4 . We studied the charge ordering transition of LiMn2O4 by means of anelastic spectroscopy, measuring the Young's modulus, E, and the elastic energy loss function, Q-1. Our measurements confirm the occurrence of a phase transition at 292 K on cooling, showing a large hysteresis on heating. The anelastic spectroscopy results also indicate that the transformation is characterised by the coexistence of two phases. In addition, the Young's modulus reveals presence of an additional anomaly, on cooling, around the onset of the phase transformation.
PREDICTING FAULT-PRONE SOFTWARE MODULES IN EMBEDDED SYSTEMS WITH CLASSIFICATION TREES
Authors: KHOSHGOFTAAR TAGHI M. , ALLEN EDWARD B. 
Published: July 2002

Embedded-computer systems have become essential to life in modern society. For example, the backbone of society's information infrastructure is telecommunications. Embedded systems must have highly reliable software, so that we avoid the severe consequences of failures, intolerable down-time, and expensive repairs in remote locations. Moreover, today's fast-moving technology marketplace mandates that embedded systems evolve, resulting in multiple software releases embedded in multiple products. Software quality models can be valuable tools for software engineering of embedded systems, because some software-enhancement techniques are so expensive or time-consuming that it is not practical to apply them to all modules. Targeting such enhancement techniques is an effective way to reduce the likelihood of faults discovered in the field. Research has shown software metrics to be useful predictors of software faults. A software quality model is developed using measurements and fault data from a past release. The calibrated model is then applied to modules currently under development. Such models yield predictions on a module-by-module basis. This paper examines the Classification And Regression Trees (CART) algorithm for building tree-based models that predict which software modules have high risk of faults to be discovered during operations. CART is attractive because it emphasizes pruning to achieve robust models. This paper presents details on the CART algorithm in the context of software engineering of embedded systems. We illustrate this approach with a case study of four consecutive releases of software embedded in a large telecommunications system. The level of accuracy achieved in the case study would be useful to developers of an embedded system. The case study indicated that this model would continue to be useful over several releases as the system evolves.
Growth Disturbance of the Paralytic Limb in Newborn Brachial Plexus Palsy
Authors: Hamada Yasuhiko , Kawabata Hidehiko , Yasui Natsuo , Kitano Motohiro , Masatomi Takashi 
Published: July 2002

Growth disturbance of the paralytic limb was analyzed in 50 patients with newborn brachial plexus palsy. The ratio of the bone length on the paralyzed side to that on the normal side as depicted on the roentogenogram was calculated at the average age of 7.2 years. While in upper type palsy the ratio was 95% in the humerus, 97% in the radius, and 96% in the ulna, that in total type palsy was 93%, 89%, and 88%, respectively. In mild paralysis, it was 95%, 98%, and 97%, respectively, while in severe paralysis, it was 93%, 88%, and 88%, respectively. In those who underwent neurosurgical reconstruction, it was 94%, 93%, and 92%, respectively, while in those who did not, it was 92%, 84%, and 85%, respectively. The degree of shortening was well correlated with the extent and severity of paralysis, and early neurosurgical reconstruction was found to reduce it.
THE MAGNETIC RESONANCE IMAGING OF THE LUMBAR SPINE IN OUT-PATIENTS WITH LOW BACK PAIN
Authors: CHEN BOHUA , LAVENDER STEVE , ANDERSSON GUNNAR B. J. 
Published: July 2002

This paper aims to estimate the prevalence rates of MRI change in LBP out-patients and to determine the relationship between abnormalities in an MRI and personal and occupational factors. The MRI records were obtained from 200 out-patients with LBP (114 males and 86 females) who received a diagnostic MRI at St. Luke's Medical Center. The mean and standard deviation of this sample's age were 43.8 years and 14.8 years, respectively. Based on the MRI, each lumbar disc was scored as normal or degenerated. Bulging and herniated were also recorded. Each patient completed a short questionnaire that included the measures of height, weight, age, and present occupation and any history of "heavy manual labor". Occupations were grouped into white collar sedentary, white collar professional, blue collar exposed to prolonged sitting and vibration, blue collar exposed to heavy, unemployed or retired, and homemaker. Chi-square tests were used to determine the statistical significance of these trends. A multiple logistic regression was used to develop a predictive model of spine pathology based on a subject's individual characteristics and occupational classification.Normal discs were found in 26% of the patients and degenerated discs in 47.5%. There were bulging/herniated disks in 26.5%. In men who were younger than 29 years, 50% had herniated disks, and 50% were normal. Three fourth of the women in the same age group showed normal discs. Forty-three percent of the subjects reported a history of performing heavy labor. Using the logistic regression model there were two variables predictive of observable MRI pathology: age and prior history of heavy labor. The analysis indicated that an older individual who had a history and heavy labor was more likely to show one or more pathological model discs in an MRI scan.
Rule-based optimization and query processing in an extensible geometric database system
Authors: Becker Ludger , Güting Ralf Hartmut 
Published: July 2002

Gral is an extensible database system, based on the formal concept of a many-sorted relational algebra. Many-sorted algebra is used to define any application's query language, its query execution language, and its optimiztion rules. In this paper we describe Gral's optimization component. It provides (1) a sophisticated rule language—rules are transformations of abstract algebra expressions, (2) a general optimization framework under which more specific optimization algorithms can be implemented, and (3) several control mechanisms for the application of rules. An optimization algorithm can be specified as a series of steps. Each step is defined by its own collection of rules together with a selected control strategy.
The general facilities are illustrated by the complete design of an example optimizer—in the form of a rule file—for a small nonstandard query language and an associated execution language. The query language includes selection, join, ordering, embedding derived values, aggregate functions, and several geometric operations. The example shows in particular how the special processing techniques of a geometric database systems, such as spatial join methods and geometric index structures, can be integrated into query processing and optimization of a relational database system. A similar, though larger, optimizer is fully functional within the geometric database system implemented as a Gral prototype.
Contention in shared memory algorithms
Authors: Dwork Cynthia , Herlihy Maurice , Waarts Orli 
Published: July 2002

Most complexity measures for concurrent algorithms for asynchronous shared-memory architectures focus on process steps and memory consumption. In practice, however, performance of multiprocessor algorithms is heavily influenced bycontention, the extent to which processess access the same location at the same time. Nevertheless, even though contention is one of the principal considerations affecting the performance of real algorithms on real multiprocessors, there are no formal tools for analyzing the contention of asynchronous shared-memory algorithms.This paper introduces the first formal complexity model for contention in shared-memory multiprocessors. We focus on the standard multiprocessor architecture in whichnasynchronous processes communicate by applyingread, write,andread-modify-writeoperations to a shared memory. To illustrate the utility of our model, we use it to derive two kinds of results: (1) lower bounds on contention for well-known basic problems such as agreement and mutual exclusion, and (2) trade-offs between the length of the critical path (maximal number of accesses to shared variables performed by a single process in executing the algorithm) and contention for these algorithms. Furthermore, we give the first formal contention analysis of a variety of counting networks, a class of concurrent data structures inplementing shared counters. Experiments indicate that certain counting networks outperform conventional single-variable counters at high levels of contention. Our analysis provides the first formal model explaining this phenomenon.
Support for repetitive transactions and ad hoc queries in System R
Authors: Chamberlin D. D. , Astrahan M. M. , King W. F. , Lorie R. A. , Mehl J. W. , Price T. G. , Schkolnick M. , Griffiths Selinger P. , Slutz D. R. , Wade B. W. , Yost R. A. 
Published: July 2002

System R supports a high-level relational user language called SQL which may be used by ad hoc users at terminals or as an embedded data sublanguage in PL/I or COBOL. Host-language programs with embedded SQL statements are processed by the System R precompiler which replaces the SQL statements by calls to a machine-language access module. The precompilation approach removes much of the work of parsing, name binding, and access path selection from the path of a running program, enabling highly efficient support for repetitive transactions. Ad hoc queries are processed by a similar approach of name binding and access path selection which takes place on-line when the query is specified. By providing a flexible spectrum of binding times, System R permits transaction-oriented programs and ad hoc query users to share a database without loss of efficiency.
System R is an experimental database management system designed and built by members of the IBM San Jose Research Laboratory as part of a research program on the relational model of data. This paper describes the architecture of System R, and gives some preliminary measurements of system performance in both the ad hoc query and the “canned program” environments.
Interference between communicating parallel processes
Authors: Gilbert Philip , Chandler W. J. 
Published: July 2002

Various kinds of interference between communicating parallel processes have been examined by Dijkstra, Knuth, and others. Solutions have been given for the mutual exclusion problem and associated subproblems, in the form of parallel programs, and informal proofs of correctness have been given for these solutions.

In this paper a system of parallel processes is regarded as a machine which proceeds from one
state S
(i.e. a collection of pertinent data values and process configurations) to a next state
S
′ in accordance with a
transition rule S
⇒
S
′.

A set of such rules yields sequences of states, which dictate the system's behavior. The mutual exclusion problem and the associated subproblems are formulated as questions of inclusion between sets of states, or of the existence of certain sequences. A mechanical proof procedure is shown, which will either verify (prove the correctness of) or discredit (prove the incorrectness of) an attempted solution, with respect to any of the interference properties.
It is shown how to calculate transition rules from the “partial rules” by which the individual processes operate. The formation of partial rules and the calculation of transition rules are both applicable to hardware processes as well as to software processes, and symmetry between processes is not required.
Some complete calculi for matrices
Authors: Bayer Rudolf , Witzgall Christoph 
Published: July 2002

A matrix calculus is introduced with the intention of developing data structures suitable for a high level algorithmic language for mathematical programming. The paper investigates how the special structure of matrices can be described and utilized for efficient computing by saving memory space and superfluous operations.
Sequences of matrices (and sequences of sequences of matrices) are considered, and matrix operators are extended to sequence operators and cumulative operators.

Algorithms are given which use symbol manipulation of matrix expressions so as to find the forms best suited for computation. These forms are called
normal forms
. Several completeness results are obtained in the sense that for each expression an equivalent expression in normal form can be found within a specified calculus.
Education related to the use of computers in organizations
Authors: Teichroew Daniel 
Published: July 2002

The ACM Curriculum Committee on Computer Education for Management has been carrying out a study on “Curriculum Development in Management Information Systems Education in Colleges and Universities” under a grant from the National Science Foundation. This position paper provides a framework for the study.
Preliminary conclusions are presented on the need for education in administrative information systems, and appropriate college curricula and courses are suggested. Also, the role of professional societies and organizations using computers is discussed, and the plans of the Committee are outlined.
The initial approach of the Committee has been to describe the education necessary for the effective use of computers in organizations, to classify the positions for which education is required, and to survey educational programs now available.
Productivity of multiprogrammed computers—progress in developing an analytic prediction method
Authors: Lasser Daniel J. 
Published: July 2002

Multiprogramming as it is discussed here is a mode of computer operation in which two or more programs are concurrently in processor memory and proceeding, each using the same central processor unit (CPU) and input-output (I/O) channels. These programs are actually proceeding intermittently and singly, according to eligibility (readiness to proceed) and priority. It is useful to be able to represent them as proceeding continuously and simultaneously, each at an effective rate, which may be a fraction of that which it would enjoy in the absence of the other programs.
The effective progress rate of each program is sensitive to many detailed characteristics of itself and its co-residents; and simulation has been the best available method of predicting it. This paper presents the results of progress in developing an alternative to simulation, a simulation-tested iterative computation of these rates under certain situations. The algorithm is sensitive to most of the factors that control the phenomenon, including nonquantitative or topological features of the programs' structures.
On the translation of relational queries into iterative programs
Authors: Freytag Johann Christoph , Goodman Nathan 
Published: July 2002

This paper investigates the problem of translating set-oriented query specifications into iterative programs. The translation uses techniques of functional programming and program transformation.
We present two algorithms that generate iterative programs from algebra-based query specifications. The first algorithm translates query specifications into recursive programs. Those are simplified by sets of transformation rules before the algorithm generates the final iterative form. The second algorithm uses a two-level translation that generates iterative programs faster than the first algorithm. On the first level a small set of transformation rules performs structural simplification before the functional combination on the second level yields the final iterative form.
Binding Personal and Peripersonal Space: Evidence from Tactile Extinction
Authors: Vaishnavi Sandeep , Calhoun Jesse , Chatterjee Anjan 
Published: July 2002

Abstract
Behavioral and neurophysiological studies suggest that the brain constructs different representations of space. Among these representations are personal and peripersonal space. Personal space refers to the space occupied by our bodies. Peripersonal space refers to the space surrounding our bodies, which can be reached by our limbs. How these two representations are bound to give a unified sense of space in which humans act is not clear. We tested 10 patients with tactile extinction to investigate this issue. Tactile extinction is an attentional disorder in which patients are unaware of being touched on their contralesional limb if they are also touched simultaneously on their ipsilesional limb. We hypothesized that mechanisms that bind personal and peripersonal representations would improve these patients' awareness of being touched on their contralesional limbs. Visual-tactile integration and intentional movements were considered candidate mechanisms. Patients were more likely to be aware of contralesional touch when looking towards their contralesional limb than when looking towards their ipsilesional limb, and when actively moving on tactile probes than when receiving tactile stimuli passively. The improved awareness of being touched on the contralesional limb under these conditions suggests that cross-sensory and sensorimotor integration help bind personal and peripersonal space.
A Neural-Network-Based Approach to the Double Traveling Salesman Problem
Authors: Plebe Alessio , Anile Angelo Marcello 
Published: July 2002

The double traveling salesman problem is a variation of the basic traveling salesman problem where targets can be reached by two salespersons operating in parallel. The real problem addressed by this work concerns the optimization of the harvest sequence for the two independent arms of a fruit-harvesting robot. This application poses further constraints, like a collision-avoidance function.The proposed solution is based on a self-organizing map structure, initialized with as many artificial neurons as the number of targets to be reached. One of the key components of the process is the combination of competitive relaxation with a mechanism for deleting and creating artificial neurons. Moreover, in the competitive relaxation process, information about the trajectory connecting the neurons is combined with the distance of neurons from the target. This strategy prevents tangles in the trajectory and collisions between the two tours. Results of tests indicate that the proposed approach is efficient and reliable for harvest sequence planning. Moreover, the enhancements added to the pure self-organizing map concept are of wider importance, as proved by a traveling salesman problem version of the program, simplified from the double version for comparison.
A Fast Histogram-Based Postprocessor That Improves Posterior Probability Estimates
Authors: Wei Wei , Leen Todd K. , Barnard Etienne 
Published: July 2002

Although the outputs of neural network classifiers are often considered to be estimates of posterior class probabilities, the literature that assesses the calibration accuracy of these estimates illustrates that practical networks often fall far short of being ideal estimators. The theorems used to justify treating network outputs as good posterior estimates are based on several assumptions: that the network is sufficiently complex to model the posterior distribution accurately, that there are sufficient training data to specify the network, and that the optimization routine is capable of finding the global minimum of the cost function. Any or all of these assumptions may be violated in practice. This article does three things. First, we apply a simple, previously used histogram technique to assess graphically the accuracy of posterior estimates with respect to individual classes. Second, we introduce a simple and fast remapping procedure that transforms network outputs to provide better estimates of posteriors. Third, we use the remapping in a real-world telephone speech recognition system. The remapping results in a 10% reduction of both word-level error rates (from 4.53% to 4.06%) and sentence-level error rates (from 16.38% to 14.69%) on one corpus, and a 29% reduction at sentence-level error (from 6.3% to 4.5%) on another. The remapping required negligible additional overhead (in terms of both parameters and calculations). McNemar's test shows that these levels of improvement are statistically significant.