ppxscal/embedding_network huggingface dataset:
Joint Distributions of Arbitrary Variables Made Easy
Authors: Richard G. Baraniuk
Venue: Multidimensional Systems and Signal Processing (1998)

We propose a simple framework for studying certain distributions of variables beyond time-frequency and time-scale. When applicable, our results turn the theory of joint distributions of arbitrary variables into an easy exercise of coordinate transformation. While straightforward, the method can generate many distributions previously attainable only by the general construction of Cohen, including distributions of time versus inverse frequency, time versus Mellin transform (scale), and time versus chirp. In addition to providing insight into these new signal analysis tools, warp-based distributions have efficient implementations for potential use in applications.
Fingerprint Classification by Directional Image Partitioning
Authors: Raffaele Cappelli, Alessandra Lumini, Dario Maio, Davide Maltoni
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1999)

In this work, we introduce a new approach to automatic fingerprint classification. The directional image is partitioned into "homogeneous" connected regions according to the fingerprint topology, thus giving a synthetic representation which can be exploited as a basis for the classification. A set of dynamic masks, together with an optimization criterion, are used to guide the partitioning. The adaptation of the masks produces a numerical vector representing each fingerprint as a multidimensional point, which can be conceived as a continuous classification. Different search strategies are discussed to efficiently retrieve fingerprints both with continuous and exclusive classification. Experimental results have been given for the most commonly used fingerprint databases and the new method has been compared with other approaches known in the literature: As to fingerprint retrieval based on continuous classification, our method gives the best performance and exhibits a very high robustness.
Analysis of Acoustic Signatures from Moving Vehicles UsingTime-Varying Autoregressive Models
Authors: Kie B. Eom
Venue: Multidimensional Systems and Signal Processing (1999)

Time-varying autoregressive (TVAR) modeling approach for the analysis of acoustic signatures from moving vehicles is presented in this paper. Acoustic signatures from moving vehicles are nonstationary, and features extracted under the stationary assumption often result unsatisfactory performance. In TVAR modeling approach, the time-varying parameters are expanded as a linear combination of deterministic time functions. In this paper, the TVAR parameters are expanded by a low-order discrete cosine transform (DCT), since DCT is known to be close to the optimal Kahrunen-Lo&egrave;ve transform when the signal is Markov. The maximum likelihood estimation and order selection in TVAR models are also discussed. Many attributes of vehicle activities, such as vehicle type, engine speed, loading, road condition, etc., may be inferred from the estimated model parameters. The performance of the TVAR modeling approach is tested with both synthetic and real acoustic signatures. A synthetic signal containing multiple time-varying sinusoids are used to compare the performances in the estimation of time-frequency distribution with other approaches. In the experiment with acoustic signatures from moving vehicles, it is shown that the TVAR models can be effectively used to determine vehicle activities and types at close range and cruising speed.
Belief reasoning in MLS deductive databases
Authors: Hasan M. Jamil
Venue: ACM SIGMOD Record (1999)

It is envisaged that the application of the multilevel security (MLS) scheme will enhance flexibility and effectiveness of authorization policies in shared enterprise databases and will replace cumbersome authorization enforcement practices through complicated view definitions on a per user basis. However, as advances in this area are being made and ideas crystallized, the concomitant weaknesses of the MLS databases are also surfacing. We insist that the critical problem with the current model is that the belief at a higher security level is cluttered with irrelevant or inconsistent data as no mechanism for attenuation is supported. Critics also argue that it is imperative for MLS database users to theorize about the belief of others, perhaps at different security levels, an apparatus that is currently missing and the absence of which is seriously felt. The impetus for our current research is this need to provide an adequate framework for belief reasoning in MLS databases. We demonstrate that a prudent application of the concept of inheritance in a deductive database setting will help capture the notion of declarative belief and belief reasoning in MLS databases in an elegant way. To this end, we develop a function to compute belief in multiple modes which can be used to reason about the beliefs of other users. We strive to develop a poised and practical logical characterization of MLS databases for the first time based on the inherently difficult concept of non-monotonic inheritance. We present an extension of the acclaimed Datalog language, called the MultiLog, and show that Datalog is a special case of our language. We also suggest an implementation scheme for MultiLog as a front-end for CORAL.
The patchwork rejection technique for sampling from unimodal distributions
Authors: Ernst Stadlober, Heinz Zechner
Venue: ACM Transactions on Modeling and Computer Simulation (TOMACS) (1999)

We report on both theoretical developments and comutational experience with the patchwork rejection technique in Zechner and Stadlober [1993] and Zechner [1997]. The basic approach is due to Minh [1988], who suggested a special sampling method for the gamma distribution. The method's general objective is to rearrange the area below the density of histogram f (x) in the body of the distribution by certain point reflections such that variates may be generated efficiently within a large center interval. This is carried out via uniform hat functions, combined with minorizing rectangles for immediate acceptance of one transformed uniform deviate. The remaining tails of f(x) are covered by exponential functions. Experiments show that patchwork rejection algorithms are in general faster than their competitors at the cost of higher set-up times.
A survey of logical models for OLAP databases
Authors: Panos Vassiliadis, Timos Sellis
Venue: ACM SIGMOD Record (1999)

In this paper, we present different proposals for multidimensional data cubes, which are the basic logical model for OLAP applications. We have grouped the work in the field in two categories: commercial tools (presented along with terminology and standards) and academic efforts. We further divide the academic efforts in two subcategories: the relational model extensions and the cube-oriented approaches. Finally, we attempt a comparative analysis of the various efforts.
Multiple maxima of likelihood in phylogenetic trees: an analytic approach
Authors: Benny Chor, Michael D. Hendy, Barbara R. Holland, David Penny
Venue: Proceedings of the fourth annual international conference on Computational molecular biology (2000)

Maximum likelihood (ML) is a widely used criterion for selecting optimal evolutionary trees. However, little is known on the nature of the likelihood surface for trees, especially as to the frequency of multiple optima. We initiate an analytic study for identifying sequences that generate multiple optima. We report a new approach to calculating ML directly, which we have used to find large families of sequences that have multiple optima, including sequences with a continuum of optimal points. Such datasets are best supported by different (two or more) phylogenies that vary significantly in their timings of evolutionary events Some standard biological processes can lead to data with multiple optima and consequently the field needs further investigation. Our results imply that hill climbing techniques, as currently implemented in various software packages, cannot guarantee to find the global ML point, even if it is unique.
Compressing Java class files
Authors: William Pugh
Venue: ACM SIGPLAN Notices (1999)

Java class files are often distributed as jar files, which are collections of individually compressed class files (and possibility other files). Jar files are typically about 1/2 the size of the original class files due to compression. I have developed a wire-code format for collections of Java class files. This format is typically 1/2 to 1/5 of the size of the corresponding compressed jar file (1/4 to 1/10 the size of the original class files).
Integration of IT into the school curricula: perceptions of kindergarden to highschool (K-12) teachers
Authors: Conrad Shayo, Lorne Olfman, Ruth Guthrie
Venue: Proceedings of the 2000 ACM SIGCPR conference on Computer personnel research (2000)

Computer use in schools is still low compared to use in other sectors of the economy. Recent surveys have found that even in schools on the leading edge in computer use, slightly less than half (42%) of the teachers use computers for instruction. This pilot study investigates the perceptions of K-12 teachers with respect to the integration of computers into the school curricula. The study is important given the recent efforts by federal, state and local governments to stimulate the use of computers in schools. A total of 1280 teachers from a South Western USA school district participated in the survey. Preliminary analyses show that causes of non-integration of computers in the school curricula are not solely determined by individual or software characteristics but the result of interaction between individual, software, and school environment characteristics. The findings confirm interactionist theories of resistance of change.
Designing the DomeCityMoo training collaboratory
Authors: Elaine M. Raybourn
Venue: ACM SIGGROUP Bulletin (1998)

This proposal argues that designing a multi-user social-process simulation in a shared virtual environment offers unique opportunities to explore intercultural issues such as identity, power, and prejudice because its collaborative environment is much less threatening than face-to-face. In the proposed Text-Based Networked Virtual Environment (TNVE) also known as a Multi-User Dimension Object Oriented (MOO), players' narratives and experiences provide the basis for discovery and exploration in a virtual training "collaboratory." The DomeCityMOO environment is unique in that it advances our state of knowledge of the effects of designing a non-scripted collaborative social process simulation for intercultural training purposes which supports both group and individual learning in a shared virtual work space.
More Results on Eigenvector Saddlepoints and Eigenpolynomials
Authors: Mark A. Mendlovitz
Venue: SIAM Journal on Matrix Analysis and Applications (1999)

This paper extends the author's earlier work which proved that, for a certain class of Hermitian eigenproblems $AP=\lambda BP$ (including, most notably, the Toeplitz eigenproblem), the eigenvectors can be represented as saddlepoints of a special form of the Rayleigh quotient. Each saddlepoint solves a min-max/max-min optimization problem whose optimal value is the eigenvalue. The zeros of the eigenpolynomial factors are located with respect to the unit circle. These results were proved, in part, by using an inertia theorem for Stein equations. For another class of Hermitian eigenproblems $AP=\lambda BP,$ an analogous set of results are derived here using an inertia theorem for Lyapunov equations. In this case, the zeros of the eigenpolynomial factors are located with respect to the imaginary axis, and sufficient conditions for the eigenpolynomial factors to have only extended imaginary zeros are established. The highlight of the article is an important theorem that yields a general factorization of saddlepoint eigenpolynomials and parameterizes all eigenvector saddlepoint representations for an m-dimensional eigenspace. Several key extensions to the theory are also presented.
Nonsingularity of the Difference of Two Oblique Projectors
Authors: Jürgen Gross, Götz Trenkler
Venue: SIAM Journal on Matrix Analysis and Applications (1999)

For two real projectors P and Q of the same order it is shown that the difference P - Q is nonsingular if and only if the column spaces of P and Q are complementary and the row spaces of P and Q are complementary. Moreover, it is demonstrated that nonsingularity of P - Q implies nonsingularity of P + Q,I - QP, and P + Q - QP.
A robust framework for content-based retrieval by spatial similarity in image databases
Authors: Essam A. El-Kwae, Mansur R. Kabuka
Venue: ACM Transactions on Information Systems (TOIS) (1999)

A framework for retrieving images by spatial similarity (FRISS) in ima ge databases is presented. In this framework, a robust retrieval by spatial similarity (RSS) algorithm is defined as one that incorporates both directional and topological spatial constraints, retrieves similar images, and recognized images even after they undergo translation, scaling, rotation (both perfect and multiple), or any arbitrary combination of transformatioins. The FRISS framework is discussed and used as a base for comparing various existing RSS algorithms. Analysis shows that none of them satisfies all the FRISS specifications. An algorithm, SIMdtc, is then presented. SIMdtc introduces the concept of a rotation correction angle(RCA) to align objects in one image spatially closer to matching objects in another image for more accurate similarity assessment. Similarity between two images is a function of the number of common objects between them and the closeness of directional and topological spatial relationships between object pairs in both images. The SIMdtc retrieval is invariant under translation, scaling, and perfect rotation, and the algorithm is able to rank multiple rotation variants. The algorithm was tested using synthetic images and the TESSA image database. Analysis shows the robustness of the SIMdtc algorithm over current algorithms.
3D Photography Using Shadows in Dual-Space Geometry
Authors: Jean-Yves Bouguet, Pietro Perona
Venue: International Journal of Computer Vision (1999)

A simple and inexpensive approach for extracting the three-dimensional shape of objects is presented. It is based on &lsquo;weak structured lighting&rsquo;. It requires very little hardware besides the camera: a light source (a desk-lamp or the sun), a stick and a checkerboard. The object, illuminated by the light source, is placed on a stage composed of a ground plane and a back plane&semi; the camera faces the object. The user moves the stick in front of the light source, casting a moving shadow on the scene. The 3D shape of the object is extracted from the spatial and temporal location of the observed shadow. Experimental results are presented on five different scenes (indoor with a desk lamp and outdoor with the sun) demonstrating that the error in reconstructing the surface is less than 0.5% of the size of the object. A mathematical formalism is proposed that simplifies the notation and keep the algebra compact. A real-time implementation of the system is also presented.
Biprimitive Graphs of Smallest Order
Authors: Shao-Fei Du, Dragan Marušič
Venue: Journal of Algebraic Combinatorics: An International Journal (1999)

A regular and edge-transitive graph which is not vertex-transitive is said to be semisymmetric. Every semisymmetric graph is necessarily bipartite, with the two parts having equal size and the automorphism group acting transitively on each of these parts. A semisymmetric graph is called biprimitive if its automorphism group acts primitively on each part. In this paper biprimitive graphs of smallest order are determined.
The system of checking students' knowledge with the use of wide area networks
Authors: Dariusz Put, Janusz Stal, Marek Zurowicz
Venue: ACM SIGCSE Bulletin (1999)

In the situation when computers, and primarily wide area computer networks, are easily accessible, it is possible to conduct examinations with no need for the examinee and the examiner to be in the same place at the same time. This paper suggests how to carry out this postulate.
Digest of proceedings seventh IEEE workshop on hot topics in operating systems March 29-30 1999, Rio Rico, AZ
Authors: M. Satyanarayanan
Venue: ACM SIGOPS Operating Systems Review (1999)

The Seventh IEEE Workshop on Hot Topics in Operating Systems was held on March 29-30 1999 at the Rio Rico Resort amp; Country Club, south of Tucson, Arizona. The General Chair, Peter Druschel, and the Local Arrangements Chair, John Hartman, had gone to considerable effort to make the operation of the workshop smooth and pleasant for the participants. The secluded desert locale, the effect of brilliant sunshine and blue skies on winter-jaded northerners, and the enthusiasm and energy of the participants all combined to offer an ideal setting for two days of technical exchange and out-of-the-box thinking. A variety of outdoor activities awaited participants who arrived early, and a kickoff reception on Sunday evening enabled participants to get to know each other before the technical meetings began.What follows is a summary of the discussions that took place during the workshop. It is meant to be a supplement, not a substitute, for the papers in the proceedings. Rather than producing a verbatim transcript, I've tried to focus on those interactions that seemed most insightful, controversial or evoked most response from the audience. Any such report must, by its very nature, be subjective. I've tried hard to be objective, but I'm sure that are some places where my personal biases show through. My apologies in advance if you attended the workshop and your favorite comment, question or discussion isn't mentioned here. This material is based on detailed notes taken by four student volunteers (Gretta Bartels, Buck Krasic, Rajeev Balasubramonian, and Ben Fleis). They did an excellent job of taking detailed and complete notes: any errors or omissions in this digest are my responsibility, not theirs.
FACT: a learning based Web query processing system
Authors: Songting Chen, Yanlei Diao, Hongjun Lu, Zengping Tian
Venue: ACM SIGMOD Record (2000)

Though the query is posted in key words, the returned results contain exactly the information that the user is querying for, which may not be explicitly specified in the input query.The required information is often not contained in the Web pages whose URLs are returned by a search engine. FACT is capable of navigating in the neighborhood of these pages to find those that really contain the queried segments.The system does not require a prior knowledge about users such as user profiles [1] or preprocessing of Web pages such as wrapper generation [2].A prototype system has been implemented using the approach. It learns and applies two types of knowledge, navigation knowledge for following hyperlinks and classification knowledge for queried segment identification. For learning, it supports three training strategies, namely sequential training, random training and interleaved training. Yahoo! is currently the external search engine. The URLs of Web pages returned by the external search engine are used in processing. A set of experiments that are designed to evaluate the system, and compare different implementations, such as knowledge representations and training strategies.
Revolutionizing name authority control
Authors: M. M. M. Snyman, M. Jansen van Rensburg
Venue: Proceedings of the fifth ACM conference on Digital libraries (2000)

A new model has been developed for the standardization of names in bibliographic databases. This paper describes the model and its implementation and also compares it with an existing model. The results show that the new model will revolutionize name authority control and will also improve on the existing NACO model. A prototype that was developed also indicates the technical feasibility of the model's implementation.
A Basis for the Top Homology of a Generalized Partition Lattice
Authors: Julie Kerr
Venue: Journal of Algebraic Combinatorics: An International Journal (1999)

For a fixed positive integer k, consider the collection of all affine hyperplanes in n-space given by xi &minus; xj &equals; m, where i, j &isin; [n], i &ne; j, and m &isin; &lcub;0, 1, &hellip;, k&rcub;. Let Ln,k be the set of all nonempty affine subspaces (including the empty space) which can be obtained by intersecting some subset of these affine hyperplanes. Now give Ln,k a lattice structure by ordering its elements by reverse inclusion. The symmetric group Gn acts naturally on Ln,k by permuting the coordinates of the space, and this action extends to an action on the top homology of Ln,k. It is easy to show by computing the character of this action that the top homology is isomorphic as an Gn-module to a direct sum of copies of the regular representation, CGn. In this paper, we construct an explicit basis for the top homology of Ln,k, where the basis elements are indexed by all labelled, rooted, (k + 1)-ary trees on n-vertices in which the root has no 0-child. This construction gives an explicit Gn-equivariant isomorphism between the top homology of Ln,k and a direct sum of copies of CGn.
Reduced Multilinear Constraints: Theory and Experiments
Authors: Anders Heyden
Venue: International Journal of Computer Vision (1998)

This paper deals with the problem of reconstructing the locations of n points in space from m different images without camera calibration. We will show how these reconstruction problems for different n and m can be put into a similar theoretical framework. This will be done using a special choice of coordinates, both in the object and in the images, called reduced affine coordinates. This choice of coordinates simplifies the analysis of the multilinear geometry and gives simpler forms of the multilinear tensors.In particular, we will investigate the cases, which can be solved by linear methods, i.e., &ge;8 points in 2 images, &ge;7 points in 3 images and &ge;6 points in 4 images. A new concept, the reduced fundamental matrix, is introduced, which gives bilinear expressions in the image coordinates. It has six nonzero elements, which depend on just four parameters and can be used to make reconstruction from 2 images. We also introduce the concept of the reduced trifocal tensor, which gives trilinear expressions in the image coordinates in 3 images. It has 15 nonzero elements and depends on nine parameters and can be used to make reconstruction from 3 images. Finally, the reduced quadfocal tensor is introduced, which describes the relations between points in 4 images and gives quadlinear expressions in the image coordinates. This tensor has 36 nonzero elements which depend on 14 independent parameters and can be used to make reconstruction from 4 images. These tensors give the possibility to calculate linear solutions from &ge;8 points in 2 images, &ge;7 points in 3 images and also from &ge;6 points in 4 images.Furthermore, a canonical form of the camera matrices in a sequence is presented and it is shown that the quadlinear constraints can be calculated from the trilinear ones, and that in general the trilinear constraints can be calculated from the bilinear ones.