ppxscal/embedding_network huggingface dataset:
Feature Subset Selection within a Simulated Annealing DataMining Algorithm
Authors: Justin C. W. Debuse, Victor J. Rayward-Smith
Venue: Journal of Intelligent Information Systems (1997)

An overview of the principle feature subset selection methods is given. We investigate a number of measures of feature subset quality, using large commercial databases. We develop an entropic measure, based upon the information gain approach used within ID3 and C4.5 to build trees, which is shown to give the best performance over our databases. This measure is used within a simple feature subset selection algorithm and the technique is used to generate subsets of high quality features from the databases. A simulated annealing based data mining technique is presented and applied to the databases. The performance using all features is compared to that achieved using the subset selected by our algorithm. We show that a substantial reduction in the number of features may be achieved together with an improvement in the performance of our data mining system. We also present a modification of the data mining algorithm, which allows it to simultaneously search for promising feature subsets and high quality rules. The effect of varying the generality level of the desired pattern is also investigated.
Conducting experiments with Experiment Manager
Authors: Michael Angel
Venue: Proceedings of the 28th conference on Winter simulation (1996)

This tutorial demonstrates how to conduct experiments and perform analysis with Experiment Manager, CACI's tool for design and analysis of simulation experiments. Experiment Manager works in conjunction with SIMPROCESS and provides a quick and object oriented approach to designing simulation experiments. The tutorial will describe how to conduct a full factorial experiment with 2 factors and 3 levels each. These experiments will be performed using a model constructed in SIMPROCESS and the results will be analyzed using such features of Experiment Manager as box plots, confidence intervals, and time series plots.
Analysis of windowing mechanisms with infinite-state stochastic Petri nets
Authors: Alexander Ost, Boudewijn R. Haverkort
Venue: ACM SIGMETRICS Performance Evaluation Review (1998)

In this paper we present a performance evaluation of windowing mechanisms in world-wide web applications. Previously, such mechanisms have been studied by means of measurements only, however, given suitable tool support, we show that such evaluations can also be performed conveniently using infinite-state stochastic Petri nets. We briefly present this class of stochastic Petri nets as well as the approach for solving the underlying infinite-state Markov chain using matrix-geometric methods. We then present a model of the TCP slow-start congestion avoidance mechanism, subject to a (recently published) typical worldwide web workload. The model is parameterized using measurement data for a national connection and an overseas connection. Our study shows how the maximum congestion window size, the connection release timeout and the packet loss probability influence the expected number of buffered segments at the server, the connection setup rate and the connection time.
Performance interactions between P-HTTP and TCP implementations
Authors: John Heidemann
Venue: ACM SIGCOMM Computer Communication Review (1997)

This document describes several performance problems resulting from interactions between implementations of persistent-HTTP (P-HTTP) and TCP. Two of these problems tie P-HTTP performance to TCP delayed-acknowledgments, thus adding up to 200ms to each P-HTTP transaction. A third results in multiple slow-starts per TCP connection. Unresolved, these problems result in P-HTTP transactions which are 14 times slower than standard HTTP and 20 times slower than potential P-HTTP over a 10 Mb/s Ethernet. We describe each problem and potential solutions. After implementing our solutions to two of the problems, we observe that P-HTTP performs better than HTTP on a local Ethernet. Although we observed these problems in specific implementations of HTTP and TCP (Apache-1.1b4 and SunOS 4.1.3, respectively), we believe that these problems occur more widely.
Recovering 3D Motion of Multiple Objects Using Adaptive Hough Transform
Authors: Tina Yu Tian, Mubarak Shah
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1997)

We present a method to determine 3D motion and structure of multiple objects from two perspective views, using adaptive Hough transform. In our method, segmentation is determined based on a 3D rigidity constraint. Instead of searching candidate solutions over the entire five-dimensional translation and rotation parameter space, we only examine the two-dimensional translation space. We divide the input image into overlapping patches, and, for each sample of the translation space, we compute the rotation parameters of patches using least-squares fit. Every patch votes for a sample in the five-dimensional parameter space. For a patch containing multiple motions, we use a redescending M-estimator to compute rotation parameters of a dominant motion within the patch. To reduce computational and storage burdens of standard multidimensional Hough transform, we use adaptive Hough transform to iteratively refine the relevant parameter space in a "coarse-to-fine" fashion. Our method can robustly recover 3D motion parameters, reject outliers of the flow estimates, and deal with multiple moving objects present in the scene. Applications of the proposed method to both synthetic and real image sequences are demonstrated with promising results.
Power-conscious high level synthesis using loop folding
Authors: Daehong Kim, Kiyoung Choi
Venue: Proceedings of the 34th annual Design Automation Conference (1997)

In this paper, a transformation technique, called power-consciousloop folding is proposed for high level synthesis of alow power system. Our work is focused on reducing the powerconsumed by functional units through the decrease of switchingactivity in a data path dominated circuit containing loops. Thetransformation algorithm has been implemented and integratedinto a high level synthesis system for experiments. In ourexperiments, we could achieve power reduction of up to 50% forcircuits dominated by functional units.
Multi-Parameter Surfaces of Analytic Centers and Long-Step Surface-Following Interior Point Methods
Authors: Yu. Nesterov, A. Nemirovski
Venue: Mathematics of Operations Research (1998)

We develop a long-step polynomial time version of the Method of Analytic Centers for non-linear convex problems. The method traces a multi-parameter surface of analytic centers rather than the usual path, which allows to handle cases with noncentered and possibly infeasible starting point.
A Theory of Specular Surface Geometry
Authors: Michael Oren, Shree K. Nayar
Venue: International Journal of Computer Vision (1997)

A theoretical framework is introduced for the perception of specular surface geometry. When an observer moves in three-dimensional space, real scene features such as surface markings remain stationary with respect to the surfaces they belong to. In contrast, a virtual feature which is the specular reflection of a real feature, travels on the surface. Based on the notion of caustics, a feature classification algorithm is developed that distinguishes real and virtual features from their image trajectories that result from observer motion. Next, using support functions of curves, a closed-form relation is derived between the image trajectory of a virtual feature and the geometry of the specular surface it travels on. It is shown that, in the 2D case, where camera motion and the surface profile are coplanar, the profile is uniquely recovered by tracking just two unknown virtual features. Finally, these results are generalized to the case of arbitrary 3D surface profiles that are traveled by virtual features when camera motion is not confined to a plane. This generalization includes a number of mathematical results that substantially enhance the present understanding of specular surface geometry. An algorithm is developed that uniquely recovers 3D surface profiles using a single virtual feature tracked from the occluding boundary of the object. All theoretical derivations and proposed algorithms are substantiated by experiments.
Lower Bounds in Lot-Sizing Models: a Polyhedral Study
Authors: Peter Hahn, Thomas Grant, Miguel Constantino
Venue: Mathematics of Operations Research (1998)

Variable lower bounds in Mixed Integer Programs are constraints with the general form x &#8805; Ly, where x is a continuous variable and y is a binary or an integer variable. This type of constraints is present in some Lot-Sizing models, where x represents the amount of some article produced by a machine and [math not displayed] indicates whether the machine is set-up for that article (y = 1) or not (y = 0). In these models, production below some level is not allowed, in order to make full use of resources. In this paper we study, from the polyhedral viewpoint, the mixed integer models whose feasible set includes an additive constraint &#931; xj &#8804; (&#8805, =)D, and constraints Lyj &#8804; xj &#8804; Kyj, where xj are continuous variables, yj are integer or binary variables, and K is a large constant. We derive families of strong valid inequalities and show they are sufficient to describe completely the convex hulls of the sets of feasible solutions. Moreover, we develop polynomial algorithms to solve the separation problem associated to each of the families obtained. Finally, we incorporate the inequalities obtained in a cutting plane algorithm, and test their ability to solve some multi-item lot-sizing problems.
An Unsymmetric-Pattern Multifrontal Method for Sparse LU Factorization
Authors: Timothy A. Davis, Iain S. Duff
Venue: SIAM Journal on Matrix Analysis and Applications (1997)

Sparse matrix factorization algorithms for general problems are typically characterized by irregular memory access patterns that limit their performance on parallel-vector supercomputers. For symmetric problems, methods such as the multifrontal method avoid indirect addressing in the innermost loops by using dense matrix kernels. However, no efficient LU factorization algorithm based primarily on dense matrix kernels exists for matrices whose pattern is very unsymmetric. We address this deficiency and present a new unsymmetric-pattern multifrontal method based on dense matrix kernels. As in the classical multifrontal method, advantage is taken of repetitive structure in the matrix by factorizing more than one pivot in each frontal matrix, thus enabling the use of Level 2 and Level 3 BLAS. The performance is compared with the classical multifrontal method and other unsymmetric solvers on a CRAY C-98.
Stack-free process-oriented simulation
Authors: C. J. M. Booth, D. I. Bruce
Venue: ACM SIGSIM Simulation Digest (1997)

The process interaction world view is widely used in the general simulation community for its expressive power, and is supported by most modern simulation languages. In parallel discrete event simulation, however, its use remains comparatively rare due to the perceived inefficiency (and difficulty) of parallel implementations.We present a new implementation strategy for parallel process-oriented simulation languages. This innovative, semantics-based approach directly addresses two common concerns of such languages. By concentrating on the intrinsic threads of control, we avoid the proliferation of simulation objects (and their associated costs) that might result from a naive translation. More fundamentally, the primary costs associated with process-oriented languages -- those of context switching between stacks and, in an optimistic setting, of saving the state of these stacks -- are entirely eliminated since our explicit use of continuations avoids the need for stacks in the first place. We similarly obtain cheap and natural thread preemption.
Online aggregation
Authors: Joseph M. Hellerstein, Peter J. Haas, Helen J. Wang
Venue: Proceedings of the 1997 ACM SIGMOD international conference on Management of data (1997)

Aggregation in traditional database systems is performed in batch mode: a query is submitted, the system processes a large volume of data over a long period of time, and, eventually, the final answer is returned. This archaic approach is frustrating to users and has been abandoned in most other areas of computing. In this paper we propose a new online aggregation interface that permits users to both observe the progress of their aggregation queries and control execution on the fly. After outlining usability and performance requirements for a system supporting online aggregation, we present a suite of techniques that extend a database system to meet these requirements. These include methods for returning the output in random order, for providing control over the relative rate at which different aggregates are computed, and for computing running confidence intervals. Finally, we report on an initial implementation of online aggregation in POSTGRES.
Composite document extended retrieval: an overview
Authors: Edward A. Fox
Venue: Proceedings of the 8th annual international ACM SIGIR conference on Research and development in information retrieval (1985)

Experimental information retrieval (IR) systems, some dating back to the sixties, have demonstrated the viability of fully automatic document storage and retrieval methodologies with small to medium size bibliographic collections [72]. Many of these experimental systems utilize the vector space model in which each important term (such as a word stem) identifies a different dimension in a space, so that matrix methods and vector operations can be defined on queries and documents. Statistical techniques have been very effective, and probabilistic enhancements have given additional improvements [84]. However, the basic vector space model is oriented towards recording the essential information in the text of a title/abstract combination rather than describing more complex document structures. It is necessary to extend the model in order to handle composite documents.On the other hand, commonly available retrieval systems that employ Boolean logic queries and utilize inverted file storage schemes can without modification accommodate such documents, albeit with somewhat less effectiveness than is possible with more sophisticated systems. Hence, it is also of interest to consider how Boolean logic systems can be extended to give better performance, especially with composite documents, and to integrate those approaches with vector methods.
On Restricted-Focus-of-Attention Learnability of Boolean Functions
Authors: Andreas Birkendorf, Eli Dichterman, Jeffrey Jackson, Norbert Klasner, Hans Ulrich Simon
Venue: Machine Learning (1998)

In the k-Restricted-Focus-of-Attention (k-RFA) model, only k of the n attributes of each example are revealed to the learner, although the set of visible attributes in each example is determined by the learner. While thek -RFA model is a natural extension of the PAC model, there are also significant differences. For example, it was previously known that learnability in this model is not characterized by the VC-dimension and that many PAC learning algorithms are not applicable in the k-RFA setting.In this paper we further explore the relationship between the PAC andk -RFA models, with several interesting results. First, we develop an information-theoretic characterization of k-RFA learnability upon which we build a general tool for proving hardness results. We then apply this and other new techniques for studying RFA learning to two particularly expressive function classes,k -decision-lists (k-DL) and k-TOP, the class of thresholds of parity functions in which each parity function takes at most k inputs. Among other results, we prove a hardness result for k-RFA learnability of k-DL,k &le; n-2 . In sharp contrast, an (n-1)-RFA algorithm for learning (n-1)-DL is presented. Similarly, we prove that 1-DL is learnable if and only if at least half of the inputs are visible in each instance. In addition, we show that there is a uniform-distribution k-RFA learning algorithm for the class ofk -DL. For k-TOP we show weak learnability by ak -RFA algorithm (with efficient time and sample complexity for constant k) and strong uniform-distribution k-RFA learnability of k-TOP with efficient sample complexity for constant k. Finally, by combining some of our k-DL and k-TOP results, we show that, unlike the PAC model, weak learning does not imply strong learning in thek -RFA model.
Robot control techniques: Part one: a review of robotics languages
Authors: Paul Frenger
Venue: ACM SIGPLAN Notices (1997)

This two-part paper describes the author's recent experiences with robot control systems. First, three principal programming techniques are reviewed, including dedicated robotics languages; machine tool languages; and general purpose computer programming languages. Then, unconventional languages for robot control, such as PostScript and Java, are discussed. In the next installment, the use of Forth as an object-oriented language to develop the author's multiprocessor android control system is explored.
Integrating External and Internal Clock Synchronization
Authors: Christof Fetzer, Flaviu Cristian
Venue: Real-Time Systems (1997)

We address the problem of how to integrate fault-tolerant external and internal clock synchronization. In this paper we propose a new external/internal clock synchronization algorithm which provides both external and internal clock synchronization for as long as a majority of the reference time servers (servers with access to reference time) stay correct. When half or more of the reference time servers are faulty, the algorithm degrades to a fault-tolerant internal clock synchronization algorithm. We prove that at least 2 F+1 reference time servers are necessary for achieving external clock synchronization when up to F reference time servers can suffer arbitrary failures, thus the proposed algorithm provides maximum fault-tolerance. In this paper we also derive lower bounds for the best maximum external deviation achievable in standard mode and the best drift rate achievable in degraded mode. Our algorithm is optimal with respect to these two bounds: (1) the maximum external deviation is optimal in standard mode, and (2) the drift rate of the clocks is optimal in standard and degraded mode.
Revenge of the Semicoarsening Frequency Decomposition Multigrid Method
Authors: J. E. Dendy,  Jr.
Venue: SIAM Journal on Scientific Computing (1997)

The frequency decomposition multigrid method was previously considered and modified so as to obtain robustness for problems with discontinuous coefficients while retaining robustness for problems with anisotropic coefficients. The application of this modified method to a problem arising in global ocean modeling was also considered. For this problem it was shown that the discretization employed gives rise to an operator for which point relaxation is not robust. In fact, alternating line relaxation is required for robustness, negating the main advantage of the frequency decomposition method: robustness for anisotropic operators using only point relaxation. In this paper a semicoarsening variant, which requires line relaxation in one direction only, is considered, and it is shown that this variant works well for the global ocean modeling problem.
Control of structure and evaluation
Authors: J. Philip Benkard
Venue: Proceedings of the international conference on APL: APL and the future (1986)

Scalar conformance controls the structure phase of expression evaluation. Program control of this phase is achieved through insertion and deletion of scalar levels of structure. The basic functions to do this are ENCLOSE and DISCLOSE with axis. Their application in some common cases is made easier with proposed extensions to BRACKET INDEX and INTERVAL. This approach provides the function of a RANK operator with greater flexibility while keeping data structure information with the data. A number of simple expression transformations have proved useful experimentally. Two operators are defined which in their several invocations provide full and partial currying and commutation of left and right arguments; composition, power, and dual of functions; composition, conversion between dyadic and monadic function syntax. The variations in the definitions of partitions have led to suggestions that more than one primitive operation may be needed. Extensions to EACH and ENCLOSE are proposed which provide a wide range of function while satisfying numerous identities. Since these two operations are each used in APL2 to create a level of structure, the extensions are appropriate.
Efficient Verification of Parallel Real&ndash;Time Systems
Authors: Tomohiro Yoneda, Bernd--Holger Schlingloff
Venue: Formal Methods in System Design (1997)

This paper presents an efficient model checking algorithm for one&ndash;safe time Petri nets and a timed temporal logic. The approach is based on the idea of (1) using only differences of timing variables to be able to construct a finite representation of the set of all reachable states and (2) further reducing the size of this representation by exploiting the concurrency in the net. This reduction of the state space is possible, because the considered linear&ndash;time temporal logic is stuttering invariant. The firings of transitions are only partially ordered by causality and a given formula; therefore the order of firings of independent transitions is irrelevant, and only one of several equivalent interleavings has to be generated for the evaluation of the given formula. In this paper the theory of timing verification with time Petri nets and temporal logic is presented, a concrete model checking algorithm is developed and proved to be correct, and some experimental results demonstrating the efficiency of the method are given.
An efficient approach to multi-layer layer assignment with application to via minimization
Authors: Chin-Chih Chang, Jason Cong
Venue: Proceedings of the 34th annual Design Automation Conference (1997)

In this paper, we present an efficient heuristic algorithmfor the layer assignment and via minimization problem formulti-layer gridless IC, PCB, and MCM layout.We introducethe notion of the extended conflict-continuation (ECC)graph to represent the multi-layer layer assignment problem.Our algorithm is based on a linear time optimal algorithmthat solves a special case of the layer assignment problemwhen the ECC graph is a tree.For the general layer assignmentconstructs a sequence of induced subtrees in theECC graph and applies our linear time optimal algorithmto each of the induced subtrees.We have applied this algorithmto the via minimization problem and get very encouragingresults.We have achieved 13%-16% via reduction onthe routing layout generated by V4R router, which is arouter known to have low usage of vias.We successfully appliedour algorithm to routing examples of over 30,000 wiresegments and over 40,000 vias.