ppxscal/embedding_network huggingface dataset:
Research-led innovation in teaching and learning programming
Authors: John Davy, Tony Jenkins
Venue: ACM SIGCSE Bulletin (1999)

We describe an attempt to bridge the gap between educational research and practical innovation by making a package of changes to an introductory programming module based on the insights of existing theoretical work. Theoretical principles are described, used to evaluate previous practices and then employed to guide systematic changes. Preliminary evaluation indicates substantial improvements in student performance and enjoyment while indicating areas in need of further work.
Detecting shared congestion of flows via end-to-end measurement
Authors: Dan Rubenstein, Jim Kurose, Don Towsley
Venue: Proceedings of the 2000 ACM SIGMETRICS international conference on Measurement and modeling of computer systems (2000)

Current Internet congestion control protocols operate independently on a per-flow basis. Recent work has demonstrated that cooperative congestion control strategies between flows can improve performance for a variety of applications, ranging from aggregated TCP transmissions to multiple-sender multicast applications. However, in order for this cooperation to be effective, one must first identify the flows that are congested at the same set of resources. In this paper, we present techniques based on loss or delay observations at end-hosts to infer whether or not two flows experiencing congestion are congested at the same network resources. We validate these techniques via queueing analysis, simulation, and experimentation within the Internet.
Logics with counting and local properties
Authors: Leonid Libkin
Venue: ACM Transactions on Computational Logic (TOCL) (2000)

The expressive power of first-order logic over finite structures is limited in two ways: it lacks a recursion mechanism, and it cannot count. Overcoming the first limitation has been a subject of extensive study. A number of fixpoint logics have been introduced. and shown to be subsumed by an infinitary logic Lw&infin;w. This logic is easier to analyze than fixpoint logics, and it still lacks counting power, as it has a 0-1 law. On the counting side, there is no analog of Lw&infin;w . There are a number of logics with counting power, usually introduced via generalized quantifiers. Most known expressivityy bounds are based on the fact that counting extensions of first-order logic preserve the locality properties. This article has three main goals. First, we introduce a new logic L*&infin;w (C) that plays the same role for counting asLw&infin;w does for recursion&mdash;it subsumes a number of extensions of first-order logic with counting, and has nice properties that make it easy to study. Second, we give simple direct proof thatLw&infin;w (C) expresses only local properties: those that depend on the properties of small neighborhoods, but cannot grasp a structure as a whole. This is a general way of saying that a logic lacks a recursion mechanism. Third, we consider a finer analysis of locality of counting logics. In particular, we address the question of how local a logic is, that is, how big are those neighborhoods that local properties depend on. We get a uniform answer for a variety of logics between first-order and L*&infin;w (C). This is done by introducing a new form of locality that captures the tightest condition that the duplicator needs to maintain in order to win a game. We also use this technique to give bounds on outputs of L*&infin;w (C)-definable queries.
Lot-Sizing with Start-Up Times
Authors: Elena Katok, Holly S. Lewis, Terry P. Harrison, Francois Vanderbeck
Venue: Management Science (1998)

Many practical applications of lot-sizing and scheduling problems involve start-up times. Operations research literature contains but few studies of lot-sizing models that take start-up times explicitly into account. Here, we review some of these studies, discuss the models and their complexity, and we propose further models. We consider in particular a single-stage single-mode multi-item lot-sizing model with continuous set-ups and sequence independent start-up times, which we solve using an integer programming column generation algorithm and we develop a dynamic programming procedure for the single-item subproblem that treats the initial stock as a decision variable. We also use cutting planes developed by Constantino for the multi-item polyhedra. By combining column and cut generation, the lower bounds that we obtain before branching are on average less than 2% from an optimal solution. Our algorithm solves instances with 3 to 5 items and 24 periods in an average of 50 seconds on a modern workstation, and problems with 36 periods in an average of 750 seconds. Solutions guaranteed to be within 2% of optimality are obtained in less than 75% of these times.
Introducing empirical investigation in undergraduate operating systems
Authors: Steven Robbins
Venue: ACM SIGOPS Operating Systems Review (1998)

The undergraduate operating systems course can provide students with a valuable introduction to empirical testing and experimentation. This paper announces the availability of a process scheduling simulator designed to develop student empirical skills while they are learning part of the standard operating systems curriculum. The simulator is written in Java and available for direct experimentation via the World Wide Web. By accessing the remote URL through an appletviewer, students can permanently save input test data and simulator results generated in HTML format. Students are asked to test specified hypotheses about process scheduling and to develop their own hypotheses about the influence of different parameters on behavior. In order to devise experiments that make sense, students must understand how factors such as burst time and variability influence behavior. Interested faculty are invited to try the simulator and support materials in their operating systems classes.
Socially translucent systems: social proxies, persistent conversation, and the design of &ldquo;babble&rdquo;
Authors: Thomas Erickson, David N. Smith, Wendy A. Kellogg, Mark Laff, John T. Richards, Erin Bradner
Venue: Proceedings of the SIGCHI conference on Human factors in computing systems: the CHI is the limit (1999)

We take as our premise that it is possible and desirable to design systems that support social processes. We describe Loops, a project which takes this approach to supporting computer-mediated communication (CMC) through structural and intemctive properties such as persistence and a minimalist graphical representation of users and their activities that we call a social proxy. We discuss a prototype called Babble that has been used by our group for over a year, and has been deployed to six other groups at the Watson labs for about two months. We describe usage experiences, lessons learned, and next steps.
A Configurable Logic Based Architecture for Real-Time ContinuousSpeech Recognition Using Hidden Markov Models
Authors: Panagiotis Stogiannos, Apostolos Dollas, Vassilis Digalakis
Venue: Journal of VLSI Signal Processing Systems (2000)

An architecture is presented for real-time continuous speech recognition based on a modified hidden Markov model. The algorithm is adapted to the needs of continuous speech recognition by efficient encoding of the state space, and logarithmic encoding of the weights so that products can be computed as sums. The paper presents the algorithm and its application related modifications, the mapping of the algorithm to a special purpose architecture, and the detailed design of this architecture using configurable logic. Emphasis is given on how the attributes of the algorithm are exploited in a configurable logic based design. A concrete design example is presented with a coprocessor engine having one large FPGA, 64 Mbytes of synchronous DRAM (SDRAM), a small FPGA as a SDRAM controller, and 2 Mbytes SRAM. This engine operating at 66 MHz performs roughly nine times as fast as a high end personal computer running a fully optimized version of the same algorithm.
A video conference network management system
Authors: D. Bandyopadhyay
Venue: International Journal of Network Management (1998)

Setting up either one or multiple conferences and managing the various devices can be a very difficult task. In this article a newly developed distributed video conference management system is explained and tested. &copy; 1998 John Wiley & Sons, Ltd.
Techniques for authentication protocols and key distribution on wireless ATM networks
Authors: D. Patiyoot, S. J. Shepherd
Venue: ACM SIGOPS Operating Systems Review (1998)

With the growing acceptance of ATM as the standard for broadband networking and the increasing importance of wireless devices, it has become appropriate to extend ATM application to wireless platforms. Adding a wireless network to existing wired network creates a set of problems. Security functions have to be reconsidered since wired network security did not account for the open medium, mobile roaming. A necessary foundation for securing a network is the ability to authenticate entities. There is a need to authenticate users of the system so that the resources would not be misused by nonsubscribers. After authentication by authentication protocol, two parties who involves in communications should be able and entitle to believe that they are communicating with each other and not with intruders. In mobile networks, normally secret-key cryptography is used for authentication. In this paper, both secret key and public key are attempted to be used in wireless ATM network.
Switching Distance Between Graphs with the Same Degrees
Authors: Todd G. Will
Venue: SIAM Journal on Discrete Mathematics (1999)

A switching replaces a pair of edges ab, cd of a graph G with the pair ac, bd of $\overline{G}$. If G and H have the same degree sequence, then G can be transformed into H by a sequence of switchings. We show that finding the minimum number of switchings required to transform G into H is equivalent to finding the maximum size of a symmetric circuit partition of $G \Delta H$. Computing this latter quantity is shown to be NP-complete.
The Convergence Rate of Finite Difference Schemes in the Presence of Shocks
Authors: Bjorn Engquist, Björn Sjögreen
Venue: SIAM Journal on Numerical Analysis (1998)

Finite difference approximations generically have ${\cal O}(1)$ pointwise errors close to a shock. We show that this local error may effect the smooth part of the solution such that only first order is achieved even for formally higher-order methods. Analytic and numerical examples of this form of accuracy are given. We also show that a converging method will have the formal order of accuracy in domains where no characteristics have passed through a shock.
A Note on the Dimension of the Bivariate Spline Space over the Morgan--Scott Triangulation
Authors: Jian Song Deng, Yu Yu Feng, Jernej Kozak
Venue: SIAM Journal on Numerical Analysis (2000)

In [D. Diener, SIAM J. Numer. Anal., 27 (1990), pp. 543--551] a conjecture on the dimension of the bivariate spline space $S_{2r}^r(\triangle)$ over the Morgan--Scott triangulation was posed. In this paper, it is proved that the conjecture should be modified for all even r > 2.
The strategic use of CAD: an empirically inspired, theory-based course
Authors: Suresh K. Bhavnani, Bonnie E. John, Ulrich Flemming
Venue: Proceedings of the SIGCHI conference on Human factors in computing systems: the CHI is the limit (1999)

The inefficient use of complex computer systems has been widely reported. These studies show the persistence of inefficient methods despite many years of experience and formal training. To counteract this phenomenon, we present the design of a new course, called the Strategic Use of CAD. The course aims at teaching students efficient strategies to use a computer-aided drafting system through a two-pronged approach. Learning to See teaches students to recognize opportunities to use efficient strategies by studying the nature of the task, and Learning to Do teaches students to implement the strategies. Results from a pilot experiment show that this approach had a positive effect on the strategic behavior of students who did not exhibit knowledge of efficient strategies before the class, and had no effect on the strategic behavior of those who did. Strategic training can thus assist users in recognizing opportunities to use efficient strategies. We present the ramifications of these results on the design of training and future experiments.
Matrix Rational H2 Approximation: A Gradient Algorithm Based on Schur Analysis
Authors: Pascale Fulcheri, Martine Olivi
Venue: SIAM Journal on Control and Optimization (1998)

This paper deals with the rational approximation of specified order n to transfer functions which are assumed to be matrix-valued functions in the Hardy space for the complement of the closed unit disk endowed with the L2-norm. An approach is developed leading to a new algorithm, the first one to our knowledge which concerns matrix-transfer functions in L2-norm. This approach generalizes the ideas presented in [L. Baratchart, M. Cardelli, and M. Olivi, Automatica, 27(1991), pp. 413--418] in the scalar case but involves substantial new difficulties.Using the Douglas--Shapiro--Shields factorization of transfer functions, the criterion for the rational approximation problem above is expressed in terms of inner matrix functions of McMillan degree n. These functions, which possess a manifold structure, are represented by means of local coordinate maps obtained in [D. Alpay, L. Baratchart, and A. Gombani, Oper. Theory Adv. Appl., 73(1994), pp. 30--66] from a tangential Schur algorithm and for which the coordinates range over n copies of the unit ball. A gradient algorithm is then employed to solve the approximation problem using the coordinate maps to describe the manifold locally and changing from one coordinate map to another when required. However, while processing the gradient algorithm a boundary point can be reached. It is proved that such a point can be considered as an initial point for searching for a local minimum of lower degree while a local minimum of McMillan degree k n provides a starting point for searching for a local minimum at degree k+1. The minimization process then pursues through different degrees. The convergence of this algorithm to a local minimum of appropriate degree is proved and demonstrated on a simple example.
Discontinuity-Preserving Vector Smoothing of Multivariate MR Images Using Vector Mean Field Annealing
Authors: Youn-Sik Han, Wesley E. Snyder, Griff L. Bilbro
Venue: Journal of Mathematical Imaging and Vision (1998)

We consider PD-, T1-, and T2-weighted magnetic resonance images jointly as a vector-valued image and use the angle of this vector field to formulate maximum a posteriori restoration as a global optimization problem. We use Mean Field Annealing (MFA) to find restorations that are superior to those obtained by previous multivariate approaches when shading artifacts near the MRI antenna are significant. Local homogeneity of the vector field as well as the angle between the components or the ratio of the components of the field are shown to have potential use for improving segmentation.
Design issues for dynamic voltage scaling
Authors: Thomas D. Burd, Robert W. Brodersen
Venue: Proceedings of the 2000 international symposium on Low power electronics and design (2000)

Processors in portable electronic devices generally have a computational load which has time-varying performance requirements. Dynamic Voltage Scaling is a method to vary the processors supply voltage so that it consumes the minimal amount of energy by operating at the minimum performance level required by the active software processes. A dynamically varying supply voltage has implications on the processor circuit design and design flow, but with some minimal constraints it is straightforward to design a processor with this capability.
Pointwise Error Estimates for Scalar Conservation Laws with Piecewise Smooth Solutions
Authors: Eitan Tadmor, Tao Tang
Venue: SIAM Journal on Numerical Analysis (1999)

We introduce a new approach to obtain sharp pointwise error estimates for viscosity approximation (and, in fact, more general approximations) to scalar conservation laws with piecewise smooth solutions. To this end, we derive a transport inequality for an appropriately weighted error function. The key ingredient in our approach is a one-sided interpolation inequality between classical L1 error estimates and Lip+ stability bounds. The one-sided interpolation, interesting for its own sake, enables us to convert a global L1 result into a (nonoptimal) local estimate. This, in turn, provides the necessary bounds on the coefficients of the above-mentioned transport inequality. Estimates on the weighted error then follow from the maximum principle, and a bootstrap argument yields optimal pointwise error bound for the viscosity approximation.Unlike previous works in this direction, our method can deal with finitely many waves with possible collisions. Moreover, in our approach one does not follow the characteristics but instead makes use of the energy method, and hence this approach could be extended to other types of approximate solutions.
Candidate subcircuits for functional module identification in logic circuits
Authors: Jennifer L. White, Anthony S. Wojcik, Moon-Jung Chung, Travis E. Doom
Venue: Proceedings of the 10th Great Lakes symposium on VLSI (2000)

Recovering functional information from existing hardware is a difficult problem in design automation. However, it is an important focus for designers attempting to redesign for expanded functionality or superior performance. Often, the only reliable information available about a piece of digital hardware is the hardware itself. Documentation, even if it is available, may be outdated or incorrect. Existing procedures are able to recover the transistor-level netlist, or a gate-level netlist from an existing implementation. The next step in this process is the gate-level to module-level transformation, the focus of this paper. We have designed a technique to enumerate all of the potential modules within a gate-level netlist so that their functional equivalence to known modules may be evaluated.
Distributed algorithms in TLA (abstract)
Authors: Leslie Lamport
Venue: Proceedings of the nineteenth annual ACM symposium on Principles of distributed computing (2000)

TLA (the temporal logic of actions) is a simple logic for describing and reasoning about concurrent systems. It provides a uniform way of specifying algorithms and their correctness properties, as well as rules for proving that one specification satisfies another. TLA+ is a formal specification language based on TLA, and TLC is a model checker for TLA+ specifications. TLA+ and TLC have been used to specify and check high-level descriptions of real, complex systems. Because TLA+ provides the full power of ordinary mathematics, it permits simple, straightforward specifications of the kinds of algorithms presented at PODC. This tutorial will try to convince you to describe your algorithms in TLA+. You will then be able to check them with TLC and use TLA to prove their correctness as formally or informally as you want. (However, TLA proofs do have one disadvantage that is mentioned below.) The tutorial will describe TLA+ through examples and demonstrate how to use TLC. No knowledge of TLA is assumed. TLA does have the following disadvantages: It can describe only a real algorithm, not a vague, incomplete sketch of an algorithm. You can specify an algorithm's correctness condition in TLA only if you understand what the algorithm is supposed to do. TLA makes it harder to cover gaps in a proof with handwaving. Some researchers may find these drawbacks insurmountable.
A Multidimensional and Multigranular Model of Time for Medical Knowledge-Based Systems
Authors: Elpida T. Keravnou
Venue: Journal of Intelligent Information Systems (1999)

In temporal reasoning there are two interrelated issues; how to model time per se and how to model occurrences. In medical temporal reasoning the need for multiple granularities and multiple conceptual temporal contexts arises in relation to a model of time. Some occurrence can then be expressed with respect to different temporal contexts. This paper presents a multidimensional and multigranular model of time for knowledge-based problem solving, primarily for medical applications. Both the conceptual issues and the design issues underlying the implementation of the proposed model are discussed. The presented model of time has been developed in the context of a time ontology for medical knowledge engineering, whose principal primitives are the time-axis and the time-object. The notion of a time-axis constitutes the primitive for the proposed model of time, while the notion of a time-object aims to integrate time with other essential forms of knowledge, such as structural and causal knowledge, in the expression of different types of occurrences, thus resulting in the integral embodiment of time in such occurrences. The notion of a time-object and the overall ontology of occurrences is given only a cursory mention in this paper. The focus of the paper is the time model. More specifically, the paper presents the notion of a time-axis in the context of the overall time ontology and discusses at length the two classes of time-axes, namely the atomic axes and the spanning axes. The assertion language which has been developed, for the entire ontology, for the expression of axioms (deductive rules and integrity constraints), attribute constraints and propagation methods is presented and illustrated. The implementation of the time model in terms of a layered object-based system is also presented.
New technology and new roles: the need for &ldquo;corpus editors&rdquo;
Authors: Gregory Crane, Jeffrey A. Rydberg-Cox
Venue: Proceedings of the fifth ACM conference on Digital libraries (2000)

Digital libraries challenge humanists and other academics to rethink the relationship between technology and their work. At the Perseus Project, we have seen the rise of a new combination of skills. The &ldquo;Corpus Editor&rdquo; manages a collection of materials that are thematically coherent and focused but are too large to be managed soley with the labor-intensive techniques of traditional editing. The corpus editor must possess a degree of domain specific knowledge and technical expertise that virtually no established graduate training provides. This new position poses a challenge to humanists as they train and support members of the field pursuing new, but necessary tasks.
The O.D. E. Method for Convergence of Stochastic Approximation and Reinforcement Learning
Authors: V. S. Borkar, S. P. Meyn
Venue: SIAM Journal on Control and Optimization (2000)

It is shown here that stability of the stochastic approximation algorithm is implied by the asymptotic stability of the origin for an associated ODE. This in turn implies convergence of the algorithm. Several specific classes of algorithms are considered as applications. It is found that the results provide (i) a simpler derivation of known results for reinforcement learning algorithms; (ii) a proof for the first time that a class of asynchronous stochastic approximation algorithms are convergent without using any a priori assumption of stability; (iii) a proof for the first time that asynchronous adaptive critic and Q-learning algorithms are convergent for the average cost optimal control problem.