ppxscal/embedding_network huggingface dataset:
The Martin Boundary of the Young-Fibonacci Lattice
Authors: Frederick M. Goodman, Sergei V. Kerov
Venue: Journal of Algebraic Combinatorics: An International Journal (2000)

In this paper we find the Martin boundary for the Young-Fibonacci lattice YF. Along with the lattice of Young diagrams, this is the most interesting example of a differential partially ordered set. The Martin boundary construction provides an explicit Poisson-type integral representation of non-negative harmonic functions on YF. The latter are in a canonical correspondence with a set of traces on the locally semisimple Okada algebra. The set is known to contain all the indecomposable traces. Presumably, all of the traces in the set are indecomposable, though we have no proof of this conjecture. Using an explicit product formula for Okada characters, we derive precise regularity conditions under which a sequence of characters of finite-dimensional Okada algebras converges.
A fast relighting engine for interactive cinematic lighting design
Authors: Reid Gershbein, Pat Hanrahan
Venue: Proceedings of the 27th annual conference on Computer graphics and interactive techniques (2000)

We present new techniques for interactive cinematic lighting design of complex scenes that use procedural shaders. Deep-framebuffers are used to store the geometric and optical information of the visible surfaces of an image. The geometric information is represented as collections of oriented points, and the optical information is represented as bi-directional reflection distribution functions, or BRDFs. The BRDFs are generated by procedurally defined surface texturing functions that spatially vary the surfaces' appearances. The deep-framebuffer information is rendered using a multi-pass algorithm built on the OpenGL graphics pipeline. In order to handle both physically-correct as well as non-realistic reflection models used in the film industry, we factor the BRDF into independent components that map onto both the lighting and texturing units of the graphics hardware. A similar factorization is used to control the lighting distribution. Using these techniques, lighting calculations can be evaluated 2500 times faster than previous methods. This allows lighting changes to be rendered at rates of 20Hz in static environments that contain millions of objects of with dozens of unique procedurally defined surface properties and scores of lights.
The Effects of Cross-Ruff Coupons on Sales and Profits
Authors: Sanjay K. Dhar, Jagmohan S. Raju
Venue: Management Science (1998)

Cross-ruff coupons are obtained at the time of purchase of a carrier brand and may be redeemed at a later date on a target brand. These coupons therefore have the ability to link consumer purchases across different brands as well as shopping trips. We model the effects of cross-ruff coupons on consumer choice behavior and derive the conditions under which cross-ruff coupons can lead to higher sales and profits than other types of package coupons. The model also provides insights into the selection of appropriate carrier and target brands, and on how the choice of an appropriate carrier or a target brand is affected when the categories that these brands belong to are demand complements or substitutes. We conduct an empirical analysis using data from 195 different cross-ruff coupon campaigns observed in grocery stores in a major U.S. city over a three-month period. The data are consistent with the key insights provided by the model.
EMC information sharing: direct access to MVS data from UNIX and NT
Authors: Walt Kohler
Venue: Proceedings of the 1999 ACM SIGMOD international conference on Management of data (1999)

In this extended abstract we briefly describe EMC's information sharing technology that enables UNIX and NT systems to directly access MVS mainframe datasets and how this technology can be used to directly access an MVS DB2 database.
Shortest-substring retrieval and ranking
Authors: Charles L. A. Clarke, Gordon V. Cormack
Venue: ACM Transactions on Information Systems (TOIS) (2000)

We present a model for arbitrary passage retrieval using Boolean queries. The model is applied to the task of ranking documents, or other structural elements, in the order of their expected relevance. Features such as phrase matching, truncation, and stemming integrate naturally into the model. Properties of Boolean algebra are obeyed, and the exact-match semantics of Boolean retrieval are preserved. Simple inverted-list file structures provide an efficient implementation. Retrieval effectiveness is comparable to that of standard ranking techniques. Since global statistics are not used, the method is of particular value in distributed environments. Since ranking is based on arbitrary passages, the structural elements to be ranked may be specified at query time and do not need to be restricted to predefined elements.
Retention and the career motives of IT professionals
Authors: Ritu Agarwal, Thomas W. Ferratt
Venue: Proceedings of the 2000 ACM SIGCPR conference on Computer personnel research (2000)

Motivated by organizational concerns related to the recruitment and retention of IT professionals, the objective of this paper is to develop and investigate an explanatory model of IT professionals' joining and staying/leaving behaviors. The underlying conceptual base for the model draws upon recent work on psychological contracts. A key dimension in this work is the preferred duration of the employment relationship. We elaborate the theory of psychological contracts with additional constructs representing an IT professional's career motives. In particular, our version of the theory suggests that, in addition to preferred length of the employment relationship, important individual factors that help form the psychological contract are the career stage of an individual and the individual's personal career anchor or orientation. Specific hypotheses related to the effects of these variables on staying/leaving behavior are presented. Empirical data gathered from a field study of 130 IT professionals were used to test the research hypotheses. Results indicate that the hypothesized variables exhibit significant effects on IT professionals' intentions to stay with their current employer. In addition, results point to directions where fruitful future research is warranted.
An analysis of Fortran utilization
Authors: N. Reid, J.P Wray
Venue: ACM SIGPLAN Fortran Forum (1999)

This paper presents the results of a survey of Fortran users. The users were asked to identify the dialects of Fortran used, other languages used, target architectures, feature utilization (data-parallel, object-orientation and abstract data typing), views on formalism in programming, and views on standard Fortran and the standardization process. The results showed that the feature requirements of sequential and parallel users are divergent, but that in general Fortran programmers are assimilating all that technology has to offer.
Accessible animation and customizable graphics via simplicial configuration modeling
Authors: Tom Ngo, Doug Cutrell, Jenny Dana, Bruce Donald, Lorie Loeb, Shunhui Zhu
Venue: Proceedings of the 27th annual conference on Computer graphics and interactive techniques (2000)

O ur goal is to em bed free-form constraints into a graphical m odel. W ith such constraints a graphic can m aintain its visual integrity&mdash; and break rules tastefully&mdash; while being m anipulated by a casualuser. A typicalparam eterized graphic does notm eet these needs because its configuration space contains nonsense im ages in m uch higher proportion than desirable im ages, and the casual user is apt to ruin the graphic on any attem pt to m odify oranim ate it. W e therefore m odel the sm all subset of a given graphic's configuration space that m aps to desirable im ages. In our solution, the basic building block is a sim plicial complex&mdash; the m ost practical data structure able to accom m odate the variety of topologies that can arise. The configuration-space m odel can be built from a cross productofsuch com plexes. W e describe how to define the m apping from this space to the im age space. W e show how to invert that m apping, allow ing the user to m anipulate the im age without understanding the structure of the configuration-space m odel. W e also show how to extend the m apping when the originalparam eterization contains hierarchy, coordinate transform ations,and other non linearities. O ur software im plem entation applies sim plicial configuration m odeling to 2D vector graphics.
Lidskii's Theorem via Nonsmooth Analysis
Authors: A. S. Lewis
Venue: SIAM Journal on Matrix Analysis and Applications (1999)

Lidskii's theorem on eigenvalue perturbation is proved via a nonsmooth mean value theorem.
Real-time programming with GNAT: specialised kernels versus POSIX threads
Authors: Juan A. de la Puente, José F. Ruiz, Jesús M. González-Barahona
Venue: Proceedings of the ninth international workshop on Real-time Ada (1999)

The fact that most of the GNAT ports are based on non real-time operating systems leads to a reduced usability for developing real-time systems. Otherwise, existing ports over real-time operating systems are excessively complex, since GNAT uses only a reduced set of their functionality, and with a very specific semantic. This paper describes the implementation of a low-level tasking support for the GNAT run-time. In order to achieve a predictable real-time behaviour we have developed a very simple library, built to fit only the GNAT tasking requirements. We have also designed a bare machine kernel which provides the minimum environment needed by the upper layers.
Browsing the structure of multimedia stories
Authors: Robert B. Allen, Jane Acheson
Venue: Proceedings of the fifth ACM conference on Digital libraries (2000)

Stories may be analyzed as sequences of causally-related events and reactions to those events by the characters. We employ a notation of plot elements, similar to one developed by Lehnert,and we extend that by forming higher level ``story threads''Stories may be analyzed as sequences of causally-related events and reactions to those events by the characters. We employ a notation of plot elements, similar to one developed by Lehnert,and we extend that by forming higher level ``story threads''We apply the browser to Corduroy, a children's short feature which was analyzed in detail. We provide additional illustrations with analysis of Kiss of Death, a Film Noir classic. Effectively, the browser provides a framework for interactive summaries, video of the narrative
Do Bounded Signals Have Bounded Amplitudes?
Authors: Patrick J. Loughlin
Venue: Multidimensional Systems and Signal Processing (1998)

There are many possible amplitudes and phases, or amplitude-modulations and frequency-modulations (AM and FM), that can generate a given signal. Of the many methods available for determining the AM and FM of a signal, some yield an unbounded AM for some magnitude-bounded signals (including the analytic signal method). The consequences of requiring a bounded AM given a bounded signal on the method used to determine the AM and FM are examined.
On-line programming examinations using Web to teach
Authors: David Arnow, Oleg Barshay
Venue: ACM SIGCSE Bulletin (1999)

Using the automated code-checking capability of the WebToTeach system, we have built WebToTest, a system for administering on-line programming examination.The system successfully addresses many of the issues raised by recent work in on-line exams by providing reliable automatic checking of exam questions and a secure, restricted programming environment useable by the students during the exam. Its web-based character makes it amenable to distance education applications. Furthermore, because examinations may be administered on any collection of computers that provide a browser, and thus do not require reservation of the student programming labs.
Asymptotic Results on the Spectra of Block Toeplitz Preconditioned Matrices
Authors: Stefano Serra
Venue: SIAM Journal on Matrix Analysis and Applications (1999)

It is well known that the generating function $f\in L^1([-\pi,\pi],{\tiny {\bf R}})$ of a class of Hermitian Toeplitz matrices An(f) describes very precisely the spectrum of each matrix of the class. [U. Grenader and G. Szegö, Toeplitz Forms and Their Applications, 2nd ed., Chelsea, New York, 1984; E. E. Tyrtyshnikov, Linear Algebra Appl., 232 (1996), pp. 1--43]. In this paper we consider n &times; n block Toeplitz matrices with m &times; m blocks generated by a Hermitian matrix-valued generating function $f\in L^1([-\pi,\pi],{\tiny {\bf C}}^{m\times m})$ and, in particular, we analyze the associated problem of preconditioning. Using previous results on this topic [P. Tilli and M. Miranda, SIAM J. Matrix Anal. Appl., to appear], we extend some theorems to this case that were proved in the one-level Toeplitz case [F. Di Benedetto, G. Fiorentino, and S. Serra, Comput. Math. Appl., 25 (1993), pp. 35--45; S. Serra, SIAM J. Matrix Anal. Appl., 17 (1996), pp. 1007--1019; S. Serra, Calcolo, 32 (1995), pp. 153--176] as well as in the two-level Toeplitz case [S. Serra, Linear Algebra Appl., 270 (1998), pp. 109--129]. This idea seems promising when dealing with linear systems arising from control theory and Markov chains theory [R. Preuss, Workshop on Toeplitz matrices in Filtering and Control, Santa Barbara, CA, August 1996; M. Neuts, Structured Stochastic Matrices of M/G/ 1 Type and Their Applications, Dekker, New York, 1989; E. Cinlar, Introduction to Stochastic Processes, Prentice--Hall, Englewood Cliffs, NJ, 1975].
Query optimization for selections using bitmaps
Authors: Ming-Chuan Wu
Venue: ACM SIGMOD Record (1999)

Bitmaps are popular indexes for data warehouse (DW) applications and most database management systems offer them today. This paper proposes query optimization strategies for selections using bitmaps. Both continuous and discrete selection criteria are considered. Query optimization strategies are categorized into static and dynamic. Static optimization strategies discussed are the optimal design of bitmaps, and algorithms based on tree and logical reduction. The dynamic optimization discussed is the approach of inclusion and exclusion for both bit-sliced indexes and encoded bitmap indexes.
A Kalman Filter Approach to Direct Depth Estimation Incorporating Surface Structure
Authors: Y. S. Hung, H. T. Ho
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1999)

The problem of depth-from-motion using a monocular image sequence is considered. A pixel-based model is developed for direct depth estimation within a Kalman filtering framework. A method is proposed for incorporating local surface structure into the Kalman filter. Experimental results are provided to illustrate the effect of structural information on depth estimation.
Graphical Illustration of Some Examples Related to the Article "Iterated Random Functions" by Diaconis and Freedman
Authors: The Editors
Venue: SIAM Review (1999)

Figures are presented to illustrate some examples of iterated random functions of the kind described in the article in this issue by Diaconis and Freedman.
Analysis of the ε-Expansion in Turbulence Theory: Approximate Renormalization Group for Diffusion of a Passive Scalar in a Random Velocity Field
Authors: Steven A. Orszag, Victor Yakhot
Venue: Journal of Scientific Computing (1999)

The validity of the &epsi;-expansion in the turbulence problem is discussed using the example of diffusion of a passive scalar in a random velocity field. A generalization of Wilson's rule for calculating a diagram of arbitrary order is introduced. The resulting perturbation series, while having zero radius of convergence, is summed exactly yielding amplitudes which differ from those obtained to lowest order in the &epsi;-expansion by only a few percent. The properties of the expansion are analyzed in detail and it is shown that various subsets of diagrams, while differing by an infinite number of terms, give close results in the vicinity of the fixed point. This indicates nontrivial compensation of high-order interactions in turbulence. The irrelevance of high-order couplings is demonstrated for arbitrary values of &epsi;. The quality the approximation is tested by comparison with numerical experiments on diffusion of a passive scalar in a band-limited random velocity field in the limit of infinite Peclet number.
A Free Moving Boundary Model and Boundary Iteration Method for Unsteady Viscous Flow in Stenotic Elastic Tubes
Authors: Dalin Tang, Jun Yang
Venue: SIAM Journal on Scientific Computing (1999)

A nonlinear mathematical model with a free moving boundary was introduced to study viscous flow in stenotic elastic tubes subject to a prescribed external pressure at the tube wall and pulsatile pressure drop between the tube inlet and outlet. An iterative numerical method using boundary iteration, pseudocompressibility, and the ADI technique was developed to solve the model. Unsteady effects of stenosis severity and the imposed pressure conditions on the tube wall and flow are studied. Special attention was paid to tube contractions because they can be indications of the tube collapsing. It was found that stenosis can cause more severe tube expansion and contraction under unsteady conditions. The complicated unsteady wall motion can be understood as the superposition of the static tube expansion and contraction caused by the stenosis and as the unsteady tube expansion and contraction caused by the imposed, unsteady pressure conditions.
A 1.5V low-power third order continuous-time lowpass &Sigma;&Delta; A/D converter (poster session)
Authors: Friedel Gerfers, Yiannos Manoli
Venue: Proceedings of the 2000 international symposium on Low power electronics and design (2000)

This paper presents the design of a 3rd-order lowpass &Sgr;&Dgr; g-to-digital (A/D) converter using a continuous-time(CT) loopfilter. The loopfilter has been implemented by using active RC-integrators. The influence of the low supply voltage on the building blocks such as the amplifier and the common mode feedback as well as on the overall &Sgr;&Dgr modulator is discussed. Simulation results of the 1.5V CT &Sgr;&Dgr; A/D converter show a 75 dB dynamic range in a bandwidth of 25kHz. The expected power consumption is less than 300&mgr;W.
Training Hidden Markov Models with Multiple Observations-A Combinatorial Method
Authors: Xiaolin Li, Marc Parizeau, Réjean Plamondon
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (2000)

Hidden Markov models (HMMs) are stochastic models capable of statistical learning and classification. They have been applied in speech recognition and handwriting recognition because of their great adaptability and versatility in handling sequential signals. On the other hand, as these models have a complex structure and also because the involved data sets usually contain uncertainty, it is difficult to analyze the multiple observation training problem without certain assumptions. For many years researchers have used Levinson's training equations in speech and handwriting applications, simply assuming that all observations are independent of each other. This paper presents a formal treatment of HMM multiple observation training without imposing the above assumption. In this treatment, the multiple observation probability is expressed as a combination of individual observation probabilities without losing generality. This combinatorial method gives one more freedom in making different dependence-independence assumptions. By generalizing Baum's auxiliary function into this framework and building up an associated objective function using the Lagrange multiplier method, it is proven that the derived training equations guarantee the maximization of the objective function. Furthermore, we show that Levinson's training equations can be easily derived as a special case in this treatment.
Verifying Timing Constraints of Real-Time Systems by Means of Evolutionary Testing
Authors: Joachim Wegener, Matthias Grochtmann
Venue: Real-Time Systems (1998)

Many industrial products are based on the use of embedded computer systems. Usually, these systems have to fulfil real-time requirements, and correct system functionality depends on their logical correctness as well as on their temporal correctness. In order to verify the temporal behavior of real-time systems, previous scientific work has, to a large extent, concentrated on static analysis techniques. Although these techniques offer the possibilty of providing safe estimates of temporal behavior for certain cases, there are a number of cases in practice for which static analysis can not be easily applied. Furthermore, no commercial tools for timing analysis of real-world programs are available. Therefore, the developed systems have to be thoroughly tested in order to detect existing deficiencies in temporal behavior, as well as to strengthen the confidence in temporal correctness. An investigation of existing test methods shows that they mostly concentrate on testing for logical correctness. They are not specialised in the examination of temporal correctness which is also essential to real-time systems. For this reason, existing test procedures must be supplemented by new methods which concentrate on determining whether the system violates its specified timing constraints. Normally, a violation means that outputs are produced too early, or their computation takes too long. The task of the tester therefore is to find the input situations with the longest or shortest execution times, in order to check whether they produce a temporal error. If the search for such inputs is interpreted as a problem of optimization, evolutionary computation can be used to automatically find the inputs with the longest or shortest execution times. This automatic search for accurate test data by means of evolutionary computation is called evolutionary testing. Experiments using evolutionary testing on a number of programs with up to 1511 LOC and 5000 input parameters have successfully identified new longer and shorter execution times than had been found using other testing techniques. Evolutionary testing, therefore, seems to be a promising approach for the verification of timing constraints. A combination of evolutionary testing and systematic testing offers further opportunities to improve the test quality, and could lead to an effective test strategy for real-time systems.
Gegenbauer Approximation in Certain Hilbert Spaces and Its Applications to Singular Differential Equations
Authors: Guo Ben-Yu
Venue: SIAM Journal on Numerical Analysis (1999)

Gegenbauer approximation in certain Hilbert spaces is investigated. Several weighted inverse inequalities and Poincar&eacute; inequalities are obtained. Some approximation results are given. Singular differential equations are approximated by using Gegenbauer polynomials. This method keeps the spectral accuracy. The main idea and techniques used in this paper are also applicable to some singular problems in multiple-dimensional spaces.
simpleIO: a Java package for novice interactive and graphics programming
Authors: Ursula Wolz, Elliot Koffman
Venue: ACM SIGCSE Bulletin (1999)

This paper describes how to incorporate user interactivity and graphics into a first course in computer science. Problems and alternative solutions are discussed. A Java package called simpleIO that we developed is presented. It allows novice programmers to build simple GUI -based programs while maintaining good design principles. The package includes methods for requesting data from the user including integers, reals, string and Booleans. It also supports simple menus, graphics displays and text file handling.