bluuebunny/crossref_metadata_2025 huggingface dataset:
CHAOS IN COUPLED ROTATORS
Authors: RUFFO STEFANO
Published: November 2004

We show that time averages of physical observables agree with ensemble averages provided chaos is present and widespread in a model system of coupled rotators. Slow relaxation is present both at low and at high temperature, where chaos is weak and inefficient. A 1.5 dimensional Hamiltonian describes the high dimensional motion quite well and allows the introduction of a Chirikov overlap parameter. A Gibbsian calculation of this parameter predicts the high temperature threshold to the statistical regime. The onset of nonlinearity is instead the mechanism which leads to the statistical regime on the low temperature side. This result should prove of interest for understanding and controlling the relaxation to equilibrium of molecular dynamics simulations. Moreover it indicates that perhaps the ergodic hypothesis is a too strong requirement.
COMPUTER SIMULATIONS OF SURFACTANT SELF ASSEMBLY
Authors: SMIT B. , HILBERS P. A. J. , ESSELINK K.
Published: November 2004

A simple oil/water/surfactant model is used to study the self-assembly of surfactants. The model contains only the most obvious elements: oil and water do not mix, and a surfactant is an amphiphilic molecule, i.e. one side of the molecule likes oil but dislikes water, the other side likes water but dislikes oil. Computer simulations on large oil/water/surfactant systems were performed on a network of 400 transputers using a parallel molecular dynamics algorithm. The simulations yield a complete micellar size distribution function. Furthermore, we observe (equilibrium) dynamical processes such as the entering of single surfactants into micelles, single surfactants leaving micelles, the fusion of two micelles, and the slow breakdown of a micelle.
ELECTRONIC STRUCTURE OF SOLIDS IN THE SELF-INTERACTION CORRECTED LOCAL-SPIN-DENSITY APPROXIMATION
Authors: SVANE AXEL
Published: November 2004

An ab-initio implementation of self-interaction corrections (SIC) within local spin density (LSD) electronic structure calculations of solids is presented. The linear-muffin-tin orbital method is used in the tight-binding representation and with the atomic spheres approximation. The variational minimum of the SIC-LSD energy functional is found by the steepest descent method, i.e., no matrix diagonalizations are involved. Special care is taken to secure stability with respect to unitarian mixing of electron states. Applied to the transition metal monoxides and La 2 CuO 4 the SIC-LSD significantly improves the desription in comparison to LSD.
A PICTURE BOOK OF TWO FAMILIES OF CUBIC MAPS
Authors: CABRAL FERNANDO , LAGO ALEXANDRE , GALLAS JASON A. C.
Published: November 2004

This paper reports high-resolution isoperiodic diagrams for two model-families of dynamical systems characterised by one-dimensional maps depending on two parameters. We present a comparison of both diagrams, investigating the way in which initial conditions affect isoperiodic sets in the parameter space of both systems and the similarities between them. Although both models represent quite different dynamical systems, they are found to have many properties in common in their space of parameters.
DISCRIMINATING ANALYSIS AND ITS APPLICATION TO MATRIX BY VECTOR MULTIPLICATION ON THE PRAM
Authors: FAVA LINDON LORRIE
Published: November 2004

We propose that a new measure of performance be applied in the analysis of PRAM algorithms, called discriminating analysis. Discriminating analysis charges Θ ( log M) time for access to a memory of size M. As well, a read is split into two primitives, a request and a receipt, with a receipt completing Ω ( log M) time units after the corresponding request is issued. A facility for pipelining of access requests is assumed. A new adaptive and optimal algorithm for matrix by vector multiplication is presented.
MAPPING BINARY PRECEDENCE TREES TO HYPERCUBES
Authors: ULLMAN STUART , NARAHARI BHAGIRATH
Published: November 2004

This paper addresses the problem of mapping the modules of a task precedence graph to the processing elements of a parallel computer. The goal of the mapping is to minimize the total execution time of the task, sum of the computation and communications time, within a processor network of limited size. We consider the special instance where the precedence graph is a binary precedence tree. We present a linear time procedure for mapping an almost full binary precedence tree of n nodes to any p processor hypercube, with unit dilation cost and optimal execution time. The computation time under the mapping is seen to be O ( n/p ) and the communications time is seen to be log p.
LOAD BALANCING STRATEGIES FOR MASSIVELY PARALLEL ARCHITECTURES
Authors: CORRADI ANTONIO , LEONARDI LETIZIA , ZAMBONELLI FRANCO
Published: November 2004

This paper explores the viability of object migration for massively parallel architectures. The aim is the comparison between global and local perspectives in migration policies. The paper reports several implemented migration algorithms and the performance obtained. The main result is that local migration policies are more viable than global ones as soon as the system size goes up.
TRANSITIVE CLOSURE IN PARALLEL ON A LINEAR NETWORK OF PROCESSORS
Authors: GASTALDO MICHEL , MORVAN MICHEL , ROBSON J. MIKE
Published: November 2004

In this paper, we propose a linear time parallel algorithm (in the number of edges of the transitive closure) that computes the transitive closure of a directed graph on a linear network of n processors. The underlying architecture is a linear network of processors with neighbouring communications, where the number of processors is equal to the number of vertices of the graph.
THE PAIRWISE SORTING NETWORK
Authors: PARBERRY IAN
Published: November 2004

A new sorting network with exactly the same size and depth as the odd-even sorting network is presented. This sorting network is designed using the zero-one principle, and proceeds by first sorting pairs of bits and then sorting the pairs into lexicographic order.
A PARALLEL PROCESSING MODEL FOR REAL-TIME COMPUTER VISION-AIDED ROAD TRAFFIC MONITORING
Authors: ALI A. T. , DAGLESS E. L.
Published: November 2004

A transputer-based parallel processing paradjgm for real-time extraction of road traffic data from video images of roadway scenes is proposed. The model can monitor three lanes of motorway traffic in real-time by processing images from two windows associated with each lane. Parallel algorithms are distributed among a network of transputers to perform similar and/or different tasks concerning image data analysis and traffic data extraction. The model can be expanded to cover more lanes or duplicated to monitor a further multi-lane carriageway.
SOME CHARACTERISTICS OF NONDETERMINISTIC PROCESSES
Authors: VIRBITSKAITE IRINA B.
Published: November 2004

The intention of the paper is to study prime event structures as models of nondeterministic processes. We characterize and examine some properties known as discreteness, density and crossing which allow inconsistency to be avoided between syntactic and semantic representations of processes. A number of close relationships between density and crossing properties of the chosen class of event structures are shown.
ON FINDING EULER TOURS IN PARALLEL
Authors: CACERES EDSON N. , DEO NARSINGH , SASTRY SHIVAKUMAR , SZWARCFITER JAYME L.
Published: November 2004

We describe an alternative implementation of Atallah and Vishkin’s parallel algorithm for finding an Euler Tour of a graph. Instead of finding a spanning tree as an intermediate step, this algorithm is based on identifying a strut which is easier to compute. Using the strut, vertices which have more than one circuit passing through them are identified directly. Stitching at such vertices reduces the number of circuits in the Euler Partition.
PRAM MEMORY ALLOCATION AND INITIALIZATION
Authors: HIGHAM LISA , SCHENK ERIC
Published: November 2004

Two techniques for managing memory on a parallel random access machine (PRAM) are presented. One is a scheme for an n/log n processor EREW PRAM that dynamically allocates and deallocates up to n records of the same size in O(log n) time. The other is a simulation of a PRAM with initialized memory by one with uninitialized memory. A CREW PRAM variant of the technique justifies the assumption that memory can be assumed to be appropriately initialized with no asymptotic increase in time but a factor of n increase in space. An EREW PRAM solution incurs a factor of O(log n) increase in time but only a constant factor increase in space.
CYLINDRICALLY SYMMETRIC SOLUTIONS OF FOUR-DIMENSIONAL σ MODELS
Authors: KISS-TOTH TIBOR
Published: November 2004

It is shown how time-dependent, cylindrically symmetric solutions can be generated for the class of SU (N) principal σ models. The superpotential for the n-step solution is derived using the inverse-scattering method of Belinsky and Zakharov.
THE SPIN-DEPENDENT STRUCTURE FUNCTIONS OF THE NUCLEON
Authors: WINDMOLDERS R.
Published: November 2004

This is an introduction to the study of the nucleon spin structure from deep inelastic lepton–nucleon scattering experiments on polarized targets. A review of the existing data is presented. The derivation of the spin–dependent structure functions from the measured spin asymmetries is analyzed and their physical interpretation is discussed in the quark–parton model. The prospects opened by several new experiments currently in preparation are also described.
GAUGE INVARIANCE AND WARD-TAKAHASHI IDENTITY IN QUANTUM MECHANICS
Authors: NAUS H.W.L. , BOS J.W. , KOCH J.H.
Published: November 2004

In a Lagrange formulation of nonrelativistic quantum mechanics gauge invariance corresponds to a local U(1) symmetry of the Lagrangian density. We review how this gauge symmetry yields the electromagnetic interaction of the free and the locally interacting N-body system and why nonlocal interactions require additional exchange contributions. A nonrelativistic Ward-Takahashi identity is then derived. This relates electromagnetic operators to the full propagator of the particles in question, which may be off their energy shell.
VERTEX OPERATORS AND REPRESENTATIONS OF QUANTUM UNIVERSAL ENVELOPING ALGEBRAS
Authors: FATEEV V.A. , LUKYANOV S.L.
Published: November 2004

This is the second part of a paper devoted to studying the quantum group structure of two-dimensional conformal field theory with additional symmetries. We construct the representation of quantum universal enveloping algebras in terms of vertex operators. The quantum version of isomonodromic deformations of ordinary differential equations is discussed.
EQUIVALENCE AMONG WORMHOLE INSTANTONS
Authors: GONZÁLEZ-DÍAZ PEDRO F.
Published: November 2004

Massless scalar fields coupled to gravity produces two kinds of wormhole instantons, the Giddings-Strominger wormhole and the Tolman-Hawking wormhole. A new type of coupling between gravity and a massless scalar field is discussed which produces a different wormhole-like solution, [Formula: see text]. It is seen that these three solutions can be related to each other by means of suitable conformal transformations. The Wheeler DeWitt equation corresponding to a fourth-order gravity theory minimally coupled to an axionic field is obtained and some of its particular solutions are discussed.
SPONTANEOUS BREAKING OF MAGNETIC FLUX SYMMETRY AND DUAL TRANSFORMATION IN (2 + 1)-DIMENSIONAL ELECTRODYNAMICS WITH FOUR-FERMI COUPLING
Authors: KOVNER A. , ELIEZER D.
Published: November 2004

We consider a class of four-fermi theories in 2 + 1 dimensions minimally coupled to electromagnetism. The low energy effective Lagrangian is derived in the Coulomb phase using a duality transformation. It is shown that the photon field (which is a Goldstone boson following from spontaneous breakdown of the magnetic flux symmetry) plays the same role as any other Goldstone boson, namely that of one of the coordinates on the order parameter manifold. Treating this Lagrangian as a quantum theory, we find that it shows the same phase structure as the original theory, giving thereby the description of the same phases and excitations in the dual language.
SYMMETRIES OF CERTAIN PHYSICAL THEORIES AND THE JORDAN ALGEBRAS
Authors: FOOT R. , JOSHI G. C.
Published: November 2004

It is shown that the sequence of Jordan algebras [Formula: see text], whose elements are the 3 × 3 Hermitian matrices over the division algebras ℝ, [Formula: see text], ℚ and [Formula: see text], can be associated with the bosonic string as well as the superstring. The construction reveals that the space–time symmetries of the first-quantized bosonic string and superstring actions can be related. The bosonic string and the superstring are associated with the exceptional Jordan algebra while the other Jordan algebras in the [Formula: see text] sequence can be related to parastring theories. We then proceed to further investigate a connection between the symmetries of supersymmetric Lagrangians and the transformations associated with the structure group of [Formula: see text]. The N = 1 on-shell supersymmetric Lagrangians in 3, 4 and 6-dimensions with a spin 0 field and a spin 1/2 field are incorporated within the Jordan-algebraic framework. We also make some remarks concerning a possible role for the division algebras in the construction of higher-dimensional extended objects.
P-VIOLATING MAGNETIC MONOPOLE INFLUENCE ON THE BEHAVIOR OF THE ATOM-LIKE SYSTEM IN EXTERNAL FIELDS
Authors: SHNIR YA. M. , TOLKACHEV E.A. , TOMIL’CHIK L.M.
Published: November 2004

The properties of the bound system charge-dyon (so-called “dyonium”) in the external electromagnetic field are considered. It is shown that the spectrum of dipole radiation of the dyonium contains direct information on spatial parity violation in electrodynamics with magnetic charge. It is found that the P noninvariance of this system leads to essential differences between the Stark and Zeeman effects for a hydrogen atom and those for dyogen. The photoionization process of the hydrogen-like atom in the field of the magnetic charge is calculated. It is shown that the corresponding angular distribution of the photoelectron has an essential asymmetry due to the P parity breaking.
APPLICATION OF THE RENORMALIZATION GROUP TO A SECOND-ORDER QCD PHASE TRANSITION
Authors: WILCZEK FRANK
Published: November 2004

An earlier suggestion that the chiral phase transition in QCD for two flavors of massless quarks might be a second-order transition has gained credibility as a result of recent numerical simulations. One can test this hypothesis, and draw very specific quantitative consequences from it, using universality and renormalization group ideas. This hypothetical second order phase transition is in the universality class of a four component isotropic Heisenberg antiferromagnet—a model which has been investigated intensely by condensed matter physicists. Existing calculations can be adapted to yield predictions for critical exponents governing the QCD transition. The perturbation due to small equal quark masses maps onto an external staggered magnetic field; that due to unequal quark masses is effective only in second order and generates a quadratic anisotropy. Several other potential applications of the renormalization group to related questions are suggested, including a model of the tricritical point which arises with finite strange quark mass, and a model for the dynamic critical behavior.
GENERALIZED c=1 MATRIX MODELS AND SYMMETRIC SPACES
Authors: OLSHANETSKY M.A.
Published: November 2004

Random matrix models with a line as a target space are considered. The models are a natural generalization of the Hermitian matrix model and connected with the classical symmetric spaces of the Euclidean type which were classified by Cartan. Ten different types of these spaces exist. Three models on a line related to these models are reduced to one-dimensional free N-fermion problems which have special symmetric configurations. The solutions in the double scaling limit to all orders of perturbation are the same as for the Hermitian matrix model. In the general case the fermions interact with the Calogero-Mozer integrable potential. Due to this fact only the planar limit can be calculated by applying the Hartree-Fock approximation procedure.
THE $K_L^0\to \pi ^0 \gamma \gamma$ DECAY IN CHIRAL PERTURBATION THEORY BASED ON THE EXTENDED NAMBU-JONA-LASINIO MODEL
Authors: IVANOV ANDREI N.
Published: November 2004

The [Formula: see text] decay is analyzed within chiral perturbation theory based on the extended Nambu-Jona-Lasinio model, which is used as a low energy approximation of QCD. The two-photon spectrum of the [Formula: see text] decay and the value of the probability [Formula: see text] are obtained in good agreement with experimental data. It is shown that the CP-conserving two-photon exchange contribution to the [Formula: see text] decay mplitude is negligibly small compared to that of the CP-violating one-photon exchange. Also presented is the derivation of the low-energy theorem for the [Formula: see text] decay amplitude in the chiral limit.
REAL-TIME CALCULATION OF THERMALLY INDUCED DECAY OF SUPERSTRING EXCITATIONS
Authors: LEBLANC Y. , TSUCHIYA A.
Published: November 2004

Decay rates of massive modes of the type I open superstring have recently been studied at zero and finite temperature. A previous imaginary-time based calculation missed a temperature-dependent contributing piece of such decay rates. We complete here the analysis by providing an analytical expression for such a missing piece for states on the leading trajectory. The results are obtained within a real-time approach to thermal strings.
SPONTANEOUS CP-VIOLATION WITHIN THE FRAMEWORK OF SU(2)L×SU(2)R×U(1) MODELS WITH MANIFEST CP INVARIANCE REVISITED
Authors: BASAK P. , DATTA A.
Published: November 2004

The case of spontaneous CP violation for large mt is reanalyzed and the validity of perturbation theory is checked by calculating the second order corrections to the CKM matrix. For a very large right-handed mass scale, the perturbation theory breaks down in some cases. While in other cases consistent with perturbation theory, the model predicts too large ε′/ε. Two possible alternatives are: (a) models with low right-handed mass scales with three generations and (b) models with heavy right-handed mass scales with four generations, avoid the above problems and values of ε′/ε and electric dipole moment of the neutron consistent with present data are obtained.
QUARK-ANTIQUARK BOUND STATES: RELATIVISTIC VERSUS NONRELATIVISTIC POINT OF VIEW
Authors: LUCHA WOLFGANG , SCHÖBERL FRANZ F.
Published: November 2004

This brief review discusses various aspects of the description of hadrons as bound states of quarks in the simpler example of mesons, which are regarded as being composite of a (constituent) quark and an antiquark. It is shown how a recently derived relativistic virial theorem may be used to cast some light on the interplay between the (semi)relativistic and (maybe only effectively) nonrelativistic treatment of bound states. Furthermore, a new relativistic approach to fermion-antifermion bound states is sketched and applied to predict analytically a few selected general features of the meson spectrum.
DEGENERATE AFFINE HECKE ALGEBRAS AND TWO-DIMENSIONAL PARTICLES
Authors: CHEREDNIK IVAN
Published: November 2004

We demonstrate that the quantization of momenta in different two dimensional theories of elementary particles with factorizable scattering amplitudes gives the so-called degenerate affine Hecke algebras and their versions. Some connections with quantum groups(Yangians), the two-dimensional conformal field theory and representation theory am discussed. In particular, an interpretation and generalizations of the difference counterpart of the Knizhnik-Zamolodchikov equation are found by means of the particles on a segment.
LAYERED CONTROL OF A BINOCULAR CAMERA HEAD
Authors: CROWLEY JAMES L. , BOBET PHILIPPE , MESRABI MOUAFAK
Published: November 2004

This paper describes a layered control system for a binocular stereo head. It begins by a discussion of the principles of layered control. It then describes the mechanical configuration for a binocular camera head with six degrees of freedom. A device level controller is presented which permits an active vision system to command the position of a binocular gaze point in the scene. The final section describes the design of perceptual actions which exploit this device level controller.
SAVIC: A SIMULATION, VISUALIZATION AND INTERACTIVE CONTROL ENVIRONMENT FOR MOBILE ROBOTS
Authors: CHEN CHUXIN , TRIVEDI MOHAN M.
Published: November 2004

A Simulation, Animation, Visualization and Interactive Control (SAVIC) environment has been developed for the design and operation of an integrated robotic manipulator system. This unique system possesses the abilities for (1) multi-sensor simulation, (2) kinematics and locomotion animation, (3) dynamic motion and manipulation animation, (4) transformation between real and virtual modes within the same graphics system, (5) ease in exchanging software modules and hardware devices between real and virtual world operations, and (6) interfacing with a real robotic system. This research is focused on enhancing the overall productivity of an integrated human-robot system. This paper describes a working system and illustrates the concepts by presenting the simulation, animation and control methodologies for a unique mobile robot with articulated tracks, a manipulator, and sensory modules.
LEARNING BLACKBOARD-BASED SCHEDULING ALGORITHMS FOR COMPUTER VISION
Authors: DRAPER BRUCE A. , HANSON ALLEN R. , RISEMAN EDWARD M.
Published: November 2004

The goal of image understanding by computer is to identify objects in visual images and (if necessary) to determine their location and orientation. Objects are identified by comparing data extracted from images to an a priori description of the object or object class in memory. It is a generally accepted premise that, in many domains, the timely and appropriate use of knowledge can substantially reduce the complexity of matching image data to object descriptions. Because of the variety and scope of knowledge relevant to different object classes, contexts and viewing conditions, blackboard architectures are well suited to the task of selecting and applying the relevant knowledge to each situation as it is encountered.

This paper reviews ten years of work on the UMass VISIONS system and its blackboard-based high-level component, the schema system. The schema system could interpret complex natural scenes when given carefully crafted knowledge bases describing the domain, but its application in practice was limited by the problem of model (knowledge base) acquisition. Experience with the schema system convinced us that learning techniques must be embedded in vision systems of the future to reduce or eliminate the knowledge engineering aspects of system construction.

The Schema Learning System (SLS) is a supervised learning system for acquiring knowledge-directed object recognition (control) strategies from training images. The recognition strategies are precompiled reactive sequences of knowledge source invocations that replace the dynamic scheduler found in most blackboard systems. Each strategy is specialized to recognize instances of a specific object class within a specific context. Since the strategies are learned automatically, the knowledge base contains only general-purpose knowledge sources rather than problem-specific control heuristics or sequencing information.
COMPARATIVE EVALUATION OF PATTERN RECOGNITION TECHNIQUES FOR DETECTION OF MICROCALCIFICATIONS IN MAMMOGRAPHY
Authors: WOODS KEVIN S. , DOSS CHRISTOPHER C. , BOWYER KEVIN W. , SOLKA JEFFREY L. , PRIEBE CAREY E. , KEGELMEYER W. PHILIP
Published: November 2004

Computer-assisted detection of microcalcifications in mammographic images will likely require a multistage algorithm that includes segmentation of possible microcalcifications, pattern recognition techniques to classify the segmented objects, a method to determine if a cluster of calcifications exists, and possibly a method to determine the probability of malignancy. This paper focuses on the first three of these stages, and especially on the classification of segmented local bright spots as either calcification or noncalcification. Seven classifiers (linear and quadratic classifiers, binary decision trees, a standard backpropagation network, 2 dynamic neural networks, and a K-nearest neighbor) are compared. In addition, a postprocessing step is performed on objects identified as calcifications by the classifiers to determine if any clusters of microcalcifications exist. A database of digitized film mammograms is used for training and testing. Detection accuracy of individual and clustered microcalcifications is compared across the seven methods using area under the ROC curve as a figure of merit.
DIGITAL SIGNAL PROCESSOR-BASED INVESTIGATION OF CHUA'S CIRCUIT FAMILY
Authors: KENNEDY MICHAEL PETER , WU CHAI WAH , PAU STANLEY , TOW JAMES
Published: November 2004

This paper is concerned with exploiting the architecture of a single-chip digital signal processor for integrating piecewise-linear ODEs. We show that DSPs can be usefully applied in the study of Chua's circuit family provided that one chooses a multistep integration algorithm which exploits their unique single-instruction multiply-and-accumulate feature.
MAXIMUM DYNAMIC RANGE OF BIFURCATION OF CHUA'S CIRCUIT
Authors: NASSER A. A. A. , HOSNY E. E. , SOBHY M. I.
Published: November 2004

This paper includes a method for detecting the maximum possible range of bifurcations based upon the multilevel oscillation technique. An application of the method to Chua's circuit, and new simulation results using the slope of the piecewise-linear function as a bifurcation parameter are presented.
MOTION ANALYSIS AND REPRESENTATION IN COMPUTER VISION
Authors: CAPPELLINI V. , MECOCCI A. , BIMBO A. DEL
Published: November 2004

Motion analysis is of high interest in many different fields for a number of crucial applications. Short-term motion analysis addresses the computation of motion parameters or the qualitative estimation of the motion field. Long-term motion analysis aims at the understanding of motion and includes reasoning on motion properties. Image sequences are in general processed to perform the above motion analysis. These subjects are considered in this review with reference to the more significant results in the literature both at theory and application levels.
COMPLEX BEHAVIOR IN DIGITAL FILTERS
Authors: OGORZAŁEK MACIEJ J.
Published: November 2004

This paper presents recent results concerning possibilities of complex behavior in extremely simple second-order digital filter structures. Two types of such behavior have been confirmed by simulation experiments and rigorous mathematical analysis: 1) chaotic behavior defined here as the existence of aperiodic, bounded trajectories displaying sensitive dependence to the initial states. Such trajectories often form very complex, self-similar patterns in the state-space. 2) an abundance of oscillatory solutions and final state sensitivity with respect to system parameters. This type of behavior can be identified by an extremely complicated structure of the parameter space (existence of Arnold tongues) and fine structure of changes of dynamic behavior when varying filter parameters (devil’s staircase). The first type of behavior has been discovered in filter sections employing two’s complement adder overflow characteristics and confirmed via symbolic dynamics technique. Properties of the second type have been found in extensive numerical experiments carried out for filter sections employing saturation arithmetic and in which a full confirmation via the mathematical analysis of an associated one-dimensional model of the system has been made.
THE STRANGE ATTRACTOR OF THE LOZI MAPPING
Authors: ZENGRONG LIU , HUIMING XIE , ZHAOXUAN ZHU , QINHE LU
Published: November 2004

In this paper, the existence of strange attractor of the Lozi mapping in the parameter region 0<b<1, 1+b<a< 2−b/2 is proved. This result coincides with numerical results. By means of the theory of transversal heteroclinic cycle, the structure of strange attractor is discussed. We conjecture that it consists entirely of unstable manifolds of infinite hyperbolic periodic points.
A TWO-LEVEL METADATA DICTIONARY APPROACH FOR SEMANTIC QUERY PROCESSING IN MULTIDATABASE SYSTEMS
Authors: PAN MIIN-JENG , CHANG SHI-KUO , YANG CHIEN-CHIAO
Published: November 2004

A multidatabase system (MDBS) is a system that integrates several autonomous database systems and provides users with a uniform access to all the databases. In this paper we developed a two-level active metadata dictionary approach for semantic query processing. To capture the global view of data schemas of participating databases which may be heterogeneous, a Hornclause data model is used. The lower-level metadata dictionaries (LLMDs) keep metadata for each corresponding local database in MDBS. The higher-level metadata dictionary (HLMD) integrates the metadata about all LLMDs. The database integration strategy includes two phases: schema translation and schema integration. It is a bottom-up approach integrating schema from the underlying database schemas. The evaluation strategy is a top-down approach. It starts with a query as a global goal to be achieved, unifies and optimizes the query to decompose the goal into subgoals that can be evaluated against extensional database, then translates these subgoals into corresponding queries against underlying DBMSs. To solve the control problem, we employ a G-net model for procedure control and inference control. An experimental implementation in Prolog is described.
COMPUTATIONAL GEOMETRY COLUMN 18
Authors: O’ROURKE JOSEPH
Published: November 2004

Results on visibility graphs are classified and organized into five tables.
OPTIMAL ROUTING THROUGH DENSE CHANNELS
Authors: WAGNER DOROTHEA
Published: November 2004

We present a new channel routing algorithm in the knock-knee mode that produces for dense problems area-optimal layouts with minimum total wire length and [Formula: see text] bends (n number of nets), where the total number of bends is at most d−2 (d density) more than the minimum. The running time is [Formula: see text]. It thus improves the algorithm in Formann et al.,3 which determines area-optimal layouts with minimum total wire length in [Formula: see text] time, where the number of bends is Ω(n2). Moreover, the algorithm can be modified so as to guarantee three-layer wirable layouts, where the total wire length is at most n−2 more than the minimum. The approach we use is completely different from all previously known algorithms. It is based on the notion of cycle graphs introduced in this paper.
PARALLEL ALGORITHMS FOR SOME DOMINANCE PROBLEMS BASED ON THE PRAM MODEL
Authors: CHAN I.W. , FRIESEN D.K.
Published: November 2004

Two parallel geometric algorithms based on the idea of point domination are presented. The first algorithm solves the d-dimensional isothetic rectangles intersection counting problem of input size N/2d, where d>1 and N is a multiple of 2d, in O( log d−1 N) time and O(N log N) space. The second algorithm solves the direct dominance reporting problem for a set of N points in the plane in O( log N+J) time and O(N log N) space, where J denotes the maximum of the number of direct dominances reported by any single point in the set. Both algorithms make use of the EREW PRAM (Exclusive Read Exclusive Write Parallel Random Access Machine) consisting of O(N) processors as the computational model.
FREE INVERSE MONOIDS AND GRAPH IMMERSIONS
Authors: MARGOLIS STUART W. , MEAKIN JOHN C.
Published: November 2004

The relationship between covering spaces of graphs and subgroups of the free group leads to a rapid proof of the Nielsen-Schreier subgroup theorem. We show here that a similar relationship holds between immersions of graphs and closed inverse submonoids of free inverse monoids. We prove using these methods, that a closed inverse submonoid of a free inverse monoid is finitely generated if and only if it has finite index if and only if it is a rational subset of the free inverse monoid in the sense of formal language theory. We solve the word problem for the free inverse category over a graph Γ. We show that immersions over Γ may be classified via conjugacy classes of loop monoids of the free inverse category over Γ. In the case that Γ is a bouquet of X circles, we prove that the category of (connected) immersions over Γ is equivalent to the category of (transitive) representations of the free inverse monoid FIM(X). Such representations are coded by closed inverse submonoids of FIM(X). These monoids will be constructed in a natural way from groups acting freely on trees and they admit an idempotent pure retract onto a free inverse monoid. Applications to the classification of finitely generated subgroups of free groups via finite inverse monoids are developed.
INVERSE MONOIDS OF DOT-DEPTH TWO
Authors: COWAN DAVID
Published: November 2004

It is shown that the pseudovariety of inverse monoids of dot-depth two is decidable and is equal to the Malcev product of the pseudovariety generated by the 5 element Brandt semigroup and the variety of semilattices.
EXTRACTING PROCEDURAL KNOWLEDGE FROM SOFTWARE SYSTEMS USING INDUCTIVE LEARNING IN THE PM SYSTEM
Authors: REYNOLDS ROBERT G. , ZANNONI ELENA
Published: November 2004

Biggerstaff and Richter suggest that there are four fundamental subtasks associated with operationalizing the reuse process [1]. They are finding reusable components, understanding these components, modifying these components, and composing components. Each of these sub-problems can be re-expressed as a knowledge acquisition sub-problem relative to producing a new representation for the components that make them more suitable for future reuse.

In this paper, we express the first two subtasks for the software reuse activity, as described by Biggerstaff and Richter, as a problem in Machine Learning. From this perspective, the goal of software reuse is to learn to recognize reusable software in terms of code structure, run-time behavior, and functional specification. The Partial Metrics (PM) System supports the acquisition of reusable software at three different levels of granularity: the system level, the procedural level, and the code segment level. Here, we describe how the system extracts procedural knowledge from an example Pascal software system that satisfies a set of structural, behavioral, and functional constraints. These constraints are extracted from a set of positive and negative examples using inductive learning techniques. The constraints are expressed quantitatively in terms of various quality models and metrics. The general characteristics of learned constraints that were extracted from a variety of applications libraries are discussed.
EFFICIENCY THROUGH REDUCED COMMUNICATION IN MESSAGE PASSING SIMULATION OF NEURAL NETWORKS
Authors: Wohl Peter
Published: November 2004

Neural algorithms require massive computation and very high communication bandwidth and are naturally expressed at a level of granularity finer than parallel systems can exploit efficiently. Mapping Neural Networks onto parallel computers has traditionally implied a form of clustering neurons and weights to increase the granularity. SIMD simulations may exceed a million connections per second using thousands of processors, but are often tailored to particular networks and learning algorithms. MIMD simulations required an even larger granularity to run efficiently and often trade flexibility for speed. An alternative technique based on pipelining fewer but larger messages through parallel. “broadcast/accumulate trees” is explored. “Lazy” allocation of messages reduces communication and memory requirements, curbing excess parallelism at run time. The mapping is flexible to changes in network architecture and learning algorithm and is suited for a variety of computer configurations. The method pushes the limits of parallelizing backpropagation and feed-forward type algorithms. Results exceed a million connections per second already on 30 processors and are up to ten times superior to previous results on similar hardware. The implementation techniques can also be applied in conjunction with others, including systolic and VLSI.
A REAL-TIME EXPERT SYSTEM FOR PROCESS MANAGEMENT—THE DESIGN AND DEVELOPMENT OF ExPro
Authors: GOLSHANI F. , KOZICKI M.N. , RASTOGI P.
Published: November 2004

We present ExPro—a real-time knowledge based system for process management. This system is designed to provide process setup, monitoring, and supervisory control capabilities for a real-time semiconductor manufacturing environment. The specific process selected for development and demonstration purposes is rapid thermal oxidation (RTO), a technique used in the controlled formation of thin silicon dioxide layers for silicon integrated circuits. This is an ideal application domain for process management system development since we can readily obtain direct process variable feedback in real-time from the equipment.

ExPro demonstrates several novelties, not the least of which is a modular design. It includes an integrated analytical simulator whose primary responsibilities are to predict process parameters a priori and to provide the necessary information on the growth of the oxide during the process. The knowledge base, in cooperation with the simulator, achieves a high degree of accuracy for control of the thickness of the wafer.
REMOTE SYSTEM INTERFACES: AN APPROACH TO OVERCOMING THE HETEROGENEITY BARRIER AND RETAINING LOCAL AUTONOMY IN THE INTEGRATION OF HETEROGENEOUS SYSTEMS
Authors: ELMAGARMID AHMED K. , CHEN JIANSAN , BUKHRES OMRAN A.
Published: November 2004

Existing and legacy software systems are the product of lengthy and individual developmental histories. Interoperability among such systems offers the support of global applications on these systems and intelligent information processing. However, interoperability among these heterogeneous systems is hampered by the absence of an integrated environment that would allow the development of global applications requiring intersystem cooperation. A uniform application-system interface is necessary to abstract the common properties of the global applications and of systems, mask their differences, and thus overcome this heterogeneity barrier. This paper presents such a solution, termed Remote System Interfaces (RSIs), which has been designed and implemented in the course of the InterBase project at Purdue University.
DESIGN AND IMPLEMENTATION OF A KNOWLEDGE-BASED QUERY PROCESSOR
Authors: ADAM NABIL R. , GANGOPADHYAY ARYYA , GELLER JAMES
Published: November 2004

This paper deals with query processing using semantic knowledge in relational databases. The Select-Project-Join (SPJ) conjunctive class of queries are dealt with in this paper. We propose to optimize highly repetitive queries by using semantic transformations in addition to syntactic transformations. Thus, we generate a set of pre-optimized queries. This set contains queries that are semantically equivalent to, syntactically different from, and more efficient to process than the user queries that we started with. The issues we address in this paper are: how to map a user query to a query that is in the set of pre-optimized and already optimized queries, how to search efficiently through the set of pre-optimized queries and set of semantic rules, and how to incorporate new queries to the set of pre-optimized queries, so that the number of queries that can be optimized using this method increases with the passage of time. Furthermore, we suggest some ideas of handling queries that do not have any semantically equivalent counterpart in the set of pre-optimized queries. We have tested the performance of the proposed method. An algorithm for mapping is implemented in Prolog. A database schema is implemented in the INGRES database management system. We have adopted a database schema that is widely used for measuring performance in the semantic query optimization literature.
REPRESENTING AND USING INTERSCHEMA KNOWLEDGE IN COOPERATIVE INFORMATION SYSTEMS
Authors: CATARCI TIZIANA , LENZERINI MAURIZIO
Published: November 2004

Managing interschema knowledge is an essential task when dealing with cooperative information systems. We propose a logical approach to the problem of both expressing interschema knowledge, and reasoning about it. In particular, we set up a structured representation language for expressing semantic interdependencies between classes belonging to different database schemas, and present a method for reasoning over such. interdependencies. The language and the associated reasoning technique makes it possible to build a logic-based module that can draw useful inferences whenever the need arises of both comparing and combining the knowledge represented in the various schemas. Notable examples of such inferences include checking the coherence of interschema knowledge, and providing integrated access to a cooperative information system.
TQFT’S FROM HOMOTOPY 2-TYPES
Authors: YETTER DAVID N.
Published: November 2004

Using techniques from [14] we construct topological quantum field theories using an algebraic model of a homotopy 2-type as initial data.
DOUBLY NULL CONCORDANT KNOTS HAVE HYPERBOLIC STABLE ISOMETRY STRUCTURES
Authors: FARBER MICHAEL S. , HILLMAN JONATHAN A.
Published: November 2004

We shall show that the stable isometry structure determined by a suitable Seifert hypersurface of a doubly null concordant knot is hyperbolic and we prove a converse for stable knots. This suggests a “universal” source for the known homological invariants of DNC-equivalence. As an application of our main result we shall show that if the homology of the universal cover of the complement of a stable n-knot is torsion, involving only primes >(n+10)/6, and is 0 in the middle dimensions then the knot is doubly null concordant.
QUANTUM INVARIANTS GIVEN BY EVALUATION OF KNOT POLYNOMIALS
Authors: MORTON H.R.
Published: November 2004

It is shown that the knot invariant arising from an irreducible representation of a quantum group is, under certain conditions, an evaluation of the Homfly or Dubrovnik polynomial of the knot.

Besides the known cases of the fundamental representation for each of the quantum groups in the series An, Bn, Cn and Dn, the results cover the special cases of the 3-dimensional representation of SU(2) and the 6-dimensional representation of SU(4), which can be viewed as the fundamental representations of SO(3) and SO(6) respectively. The second of these cases leads to a new relation between an evaluation of the Dubrovnik polynomial of a knot and an evaluation of the Homfly polynomials of two 2-cables about the knot.
INTEGRABLE CONFORMAL FIELD THEORY IN FOUR DIMENSIONS AND FOURTH-RANK GEOMETRY
Authors: TAPIA VICTOR
Published: November 2004

We consider the conformal properties of geometries described by higher-rank line elements. A crucial role is played by the conformal Killing equation (CKE). We introduce the concept of null-flat spaces in which the line element can be written as dsr=r!dζ1 … dζr. We then show that, for null-flat spaces, the critical dimension, for which the CKE has infinitely many solutions, is equal to the rank of the metric. Therefore, in order to construct an integrable conformal field theory in four dimensions we need to rely on fourth-rank geometry. We consider the simple model ℒ = ¼ Gμνλρ ∂μ ϕ ∂ν ϕ ∂λ ϕ ∂ρϕ and show that it is an integrable conformal model in four dimensions. Furthermore, the associated operators satisfy a Vir4 algebra.
A PREY-PREDATOR MODEL IN A MULTI-PATCH ENVIRONMENT WITH DIFFERENT TIME SCALES
Authors: AUGER P. , BENOÎT E.
Published: November 2004

Ecological systems are large scale systems involving a large number of variables. By aggregation, it is possible to obtain at each level of organization an approximate and simple system of differential equations which can be studied more easily than the whole system involving a very large number of variables. Important differences in the orders of magnitude of the time scales in ecological systems allow us to apply methods of perturbation theory in order to replace large scale systems by reduced systems described by a few number of global variables. Perturbation theory determines the conditions required for aggregation. As examples, we present prey-predator models taking into account the activity sequences of animals at the individual level. In this way, the predation pressure depends on the individual strategies selected by the animals. We compare numerical simulations for the whole system and for the reduced system. We show that as soon as the orders of magnitude for the slow and fast dynamics are sufficiently different, then the orbits obtained for the reduced system are very close to the orbits obtained for the whole system.
DEVELOPING LOCAL FRANCHISE: STRATEGIC PERSPECTIVE AND MODEL
Authors: ALIAS ADNAN
Published: November 2004

Franchising is a global phenomenon. In developing countries, franchising is activated both by international franchise entities and home-grown franchises. Rapid development of franchising coupled with turbulent environments have led the society to view franchising as more than just a form of business; franchising is a strategy. The Malaysian government has even looked beyond that by adopting franchising as a strategy to develop local entrepreneurship. A comprehensive model attesting to the role of the government in promoting franchising—both imported and home-grown—is presented.
COUNSELLING ENTREPRENEURS AS RESOURCES IN REGIONAL ECONOMIC DEVELOPMENT
Authors: MEREDITH GEOFFREY G. , HOWARD DENNIS
Published: November 2004

Regional economic or regional enterprise development has been subject to intense research by economists, planners, enterprise specialists and policy specialists for decades. The paper examines various models for regional economic or regional enterprise development and focuses on small towns and communities as an essential component of development. The paper reviews the role of entrepreneurs in enterprise strategies linked to towns and communities and the origins of entrepreneurs and strategies that might be adopted at the regional level to provide support for the entrepreneurial event. The results of a field study of over three hundred Australian regional development centres small enterprise clients, the strategies of those centres impact on entrepreneurs, reveal that the proposed objectives were not achieved and the strategies were in retrospect questionable. The paper concludes with recommended strategies for practitioners and policy makers dedicated to regional development and recognising the role of entrepreneurs in that process.
Niocalite-cuspidine solid solution and manganoan monticellite from natrocarbonatite, Oldoinyo Lengai, Tanzania
Authors: Mitchell R. H. , Belton F.
Published: November 2004

Lapilli and spatter of natrocarbonatite extruded from the T56B cone of Oldoinyo Lengai (Tanzania) in August 2003 are unusually rich in apatite, silicate, oxide and sulphide minerals. These minerals occur primarily within inclusions of quenched natrocarbonatite in gregoryite and fractures in nyerereite-gregoryite intergrowths. Silicates include members of the sodian cuspidine–niobian cuspidine–niocalite solid-solution series and manganoan monticellite. Oxides are represented by members of the magnesioferrite–jacobsite–magnetite solid-solution series. Sulphides occurring in decreasing order of abundance include: ferroan alabandite, manganoan ferroan sphalerite, galena and pyrrhotite. Petrographic and compositional data for these minerals are interpreted to indicate that all are high-temperature (<900–650°C), early-crystallizing phases from relatively-unevolved natrocarbonatite magma, with the sulphides forming prior to the silicates, and the latter before gregoryite. Sulphur fugacityand oxygen fugacity of natrocarbonatite magma are considered to decrease and increase, respectively, during the formation of the sulphide-oxide assemblage. Crystallization of cuspidine-niocalite, monticellite and Si-bearing apatite rapidly depletes natrocarbonatite magma of its initial low silica content, preventing crystallization of late-stage groundmass silicates.