ppxscal/embedding_network huggingface dataset:
Standards: Accommodating standards and identification of programming languages
Authors: Calvin N. Mooers
Venue: Communications of the ACM (1968)

The user public wants standardization and reliable identification of programming languages and related services. One way of achieving these goals is illustrated by the methods adopted for TRAC T-64 interactive language, and its related family of languages. Oppressive rigidity usually associated with standardization is avoided by a new accommodation technique accessible to the user to allow local variations within the language. Explicit standardization of the language is undertaken at the organizational source of the language. Use of the organizational trademark (TRAC) on the published standards, and services relying upon them, provides a reliable public identification. These methods can be useful applied to other programming languages and computer services.
A fast and accurate delay estimation method for buffered interconnects
Authors: Youxin Gao, D. F. Wong
Venue: Proceedings of the 2001 Asia and South Pacific Design Automation Conference (2001)

In this paper, we present a fast and accurate delay estimation method for buffered interconnects. The interconnect wire is modeled by the transmission line model which is more accurate and efficient than lumped circuit model. For the interconnect wire, we specify the wire shape to be of the form f(x) = ae-bx. Note that if we let b = 0, our work is reduced to uniform wire case. By using first three poles in the transfer function, we derive analytical expressions for calculating delay at any threshold voltage under a finite ramp input. The expressions involved in calculating coefficients in the transfer function are also analytical. We use k-factor equations to estimate delays for buffers. Since the k-factor equations require a loading capacitance for delay computation, we use the effective capacitance technique introduced in [17] to calculate the effective capacitance for each interconnect wire which is connected to a buffer. Therefore, our delay calculation for buffered interconnects is analytical and thus very efficient. Our experiments show that signal waveforms estimated by our method are very close to SPICE's results.
Example-Based Object Detection in Images by Components
Authors: Anuj Mohan, Constantine Papageorgiou, Tomaso Poggio
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (2001)

In this paper, we present a general example-based framework for detecting objects in static images by components. The technique is demonstrated by developing a system that locates people in cluttered scenes. The system is structured with four distinct example-based detectors that are trained to separately find the four components of the human body: the head, legs, left arm, and right arm. After ensuring that these components are present in the proper geometric configuration, a second example-based classifier combines the results of the component detectors to classify a pattern as either a ¿person¿ or a ¿nonperson.¿ We call this type of hierarchical architecture, in which learning occurs at multiple stages, an Adaptive Combination of Classifiers (ACC). We present results that show that this system performs significantly better than a similar full-body person detector. This suggests that the improvement in performance is due to the component-based approach and the ACC data classification architecture. The algorithm is also more robust than the full-body person detection method in that it is capable of locating partially occluded views of people and people whose body parts have little contrast with the background.
Incremental execution of guarded theories
Authors: Giuseppe De Giacomo, Hector J. Levesque, Sebastian Sardiña
Venue: ACM Transactions on Computational Logic (TOCL) (2001)

When it comes to building controllers for robots or agents, high level programming languages like Golog and ConGolog offer a useful compromise between planning-based approaches and low-level robot programming. However, two serious problems typically emerge in practical implementations of these languages: how to evaluate test in a program efficiently enough in an open-world setting, and how to make appropiate nondeterministic choices while avoiding full lookahead. Recent proposals in the literature suggest that one could tackle the first problem by exploiting sensing information, and tackle the second by specifying the amount of lookahead allowed explicitly in the program. In this paper, we combine these two ideas and demonstrate their power by presenting an interpreter, written in Prolog, for a variant of Golog that is suitable for efficiently operating in open-world setting by exploiting sensing and bounded lookahead.
A comparative study of the NAS MG benchmark across parallel languages and architectures
Authors: Bradford L. Chamberlain, Steven J. Deitz, Lawrence Snyder
Venue: Proceedings of the 2000 ACM/IEEE conference on Supercomputing (CDROM) (2000)

Hierarchical algorithms such as multigrid applications form an important cornerstone for scientific computing. In this study, we take a first step toward evaluating parallel language support for hierarchical applications by comparing implementations of the NAS MG benchmark in several parallel programming languages: Co-Array Fortran, High Performance Fortran, Single Assignment C, and ZPL. We evaluate each language in terms of its portability, its performance, and its ability to express the algorithm clearly and concisely. Experimental platforms include the Cray T3E, IBM SP, SGI Origin, Sun Enterprise 5500 and a high-performance Linux cluster. Our findings indicate that while it is possible to achieve good portability, performance, and expressiveness, most languages currently fall short in at least one of these areas. We find a strong correlation between expressiveness and a language's support for a global view of computation, and we identify key factors for achieving portable performance in multigrid applications.
Dynamic variables
Authors: David R. Hanson, Todd A. Proebsting
Venue: ACM SIGPLAN Notices (2001)

Most programming languages use static scope rules for associating uses of identifiers with their declarations. Static scope helps catch errors at compile time, and it can be implemented efficiently. Some popular languages&mdash;Perl, Tel, TeX, and Postscript&mdash;offer dynamic scope, because dynamic scope works well for variables that &ldquo;customize&rdquo; the execution environment, for example. Programmers must simulate dynamic scope to implement this kind of usage in statically scoped languages. This paper describes the design and implementation of imperative language constructs for introducing and referencing dynamically scoped variables&mdash;dynamic variables for short. The design is a minimalist one, because dynamic variables are best used sparingly, much like exceptions. The facility does, however, cater to the typical uses for dynamic scope, and it provides a cleaner mechanism for so-called thread-local variables. A particularly simple implementation suffices for languages without exception handling. For languages with exception handling, a more efficient implementation builds on existing compiler infrastructure. Exception handling can be viewed as a control construct with dynamic scope. Likewise, dynamic variables are a data construct with dynamic scope.
Nonlinearity, Scale, and Sensitivity for Parameter Estimation Problems
Authors: Alv-Arne Grimstad, Trond Mannseth
Venue: SIAM Journal on Scientific Computing (1999)

We study model nonlinearity and sensitivity for parameter estimation problems. Previous work has revealed a correlation between high nonlinearity, low sensitivity, and short scale for an ODE model. In this paper, we investigate whether this correlation is valid for a larger class of model functions. We set forth a proposition that says, in essence, that the correlation holds when the forward model output is an integral. Solutions to ODEs and PDEs can be viewed as integral models. If the proposition is true, it may explain an apparent conflict between earlier works on uncertainty analysis for parameter estimation problems. It could also have impact on the choice of solution algorithm for such problems. The validity of the proposition is assessed by studying nonlinearity and sensitivity for fairly general nonlinear models, and corresponding integrals of these models. Theory is developed and its predictions are tested through numerical examples. The focus is on general effects for the model classes (integrated/nonintegrated), i.e., effects that do not depend on any specific choice of model function within each class.
Copies convergence in a distributed real-time collaborative environment
Authors: Nicolas Vidot, Michelle Cart, Jean Ferrié, Maher Suleiman
Venue: Proceedings of the 2000 ACM conference on Computer supported cooperative work (2000)

In real-time collaborative systems, replicated objects, shared by users, are subject to concurrency constraints. In order to satisfy these, various algorithms, qualified as opðtimistic, [3, 5, 13, 17, 14, 15, 18], have been proposed that exploit the semantic properties of operations to serialize concurrent operations and achieve copy conðvergence of replicated objects. Their drawback is that they either reðquire a condition on user's operations which is hard to verify when possible to ensure, or they need undoðing then redoing operations in some situations. The main purpose of this paper is to present two new algorithms that overðcome these drawbacks. They are based upon the impleðmentation of a continuous global order which enables that condition to be released, and simplifies the operation inteðgration process. In the second algorithm, thanks to deðferred broadcast of operations to other sites, this process becomes even more simplified.
Locating Discontinuities of a Bounded Function by the Partial Sums of Its Fourier Series
Authors: George Kvernadze, Thomas Hagstrom, Henry Shapiro
Venue: Journal of Scientific Computing (1999)

A key step for some methods dealing with the reconstruction of a function with jump discontinuities is the accurate approximation of the jumps and their locations. Various methods have been suggested in the literature to obtain this valuable information. In the present paper, we develop an algorithm based on asymptotic expansion formulae obtained in our earlier work. The algorithm enables one to approximate the locations of discontinuities and the magnitudes of jumps of a bounded function given its truncated Fourier series. We investigate the stability of the method and study its complexity. Finally, we consider several numerical examples in order to emphasize strong and weak points of the algorithm.
Performance of multipath routing for on-demand protocols in mobile ad hoc networks
Authors: Asis Nasipuri, Robert Castañeda, Samir R. Das
Venue: Mobile Networks and Applications (2001)

Mobile ad hoc networks are characterized by multi-hop wireless links, absence of any cellular infrastructure, and frequent host mobility. Design of efficient routing protocols in such networks is a challenging issue. As class of routing protocols called on-demandprotocols hs recently found attention because of their low routing overhead. The on-demand protocols depend on query floods to discover routes whenever a new route is needed. Such floods take up a substantial portion of network bandwidth. We focus on a particular on-demand protocol, called Dynamic Source Routing, and show how intelligent use of multipath techniques can reduce the frequency of query floods. We develop an analytic modeling framework to determine the relative frequency of query floods for various techniques. Our modeling effort shows that while multipath routing is significantly better than single path routing, the performance advantage is small beyond a few paths and for long paths lengths. It also shows that providing all intermediate nodes in the primary (shortest) route with alternative paths has a significantly better performance than providing only the source with alternate paths. We perform some simulation experiments which validate these findings.
Lock-free scheduling of logical processes in parallel simulation
Authors: Jason Liu, David M. Nicol, King Tan
Venue: Proceedings of the fifteenth workshop on Parallel and distributed simulation (2001)

With fixed lookahead information in a simulation model, the overhead of asynchronous conservative parallel simulation lies in the mechanism used for propagating time updates in order for logical processes to safely advance their local simulation clocks. Studies have shown that a good scheduling algorithm should preferentially schedule processes containing events on the critical path. This paper introduces a lock-free algorithm for scheduling logical processes in conservative parallel discrete-event simulation on shred-memory multiprocessor machines. The algorithm uses fetch add operations that help avoid inefficiencies associated with using locks. The lock-free algorithm is robust. Experiments show that, compared with the scheduling algorithm using locks, the lock-free algorithm exhibits better performance when the number of logical processes assigned to each processor is small or when the workload becomes significant. In models with large number of logical processes, our algorithm shows only modest increase in execution time due to the overhead in the algorithm for extra bookkeeping.
Separating Complexity Classes Using Autoreducibility
Authors: Harry Buhrman, Lance Fortnow, Dieter van Melkebeek, Leen Torenvliet
Venue: SIAM Journal on Computing (2000)

A set is autoreducible if it can be reduced to itself by a Turing machine that does not ask its own input to the oracle. We use autoreducibility to separate the polynomial-time hierarchy from exponential space by showing that all Turing complete sets for certain levels of the exponential-time hierarchy are autoreducible but there exists some Turing complete set for doubly exponential space that is not.Although we already knew how to separate these classes using diagonalization, our proofs separate classes solely by showing they have different structural properties, thus applying Post's program to complexity theory. We feel such techniques may prove unknown separations in the future. In particular, if we could settle the question as to whether all Turing complete sets for doubly exponential time are autoreducible, we would separate either polynomial time from polynomial space, and nondeterministic logarithmic space from nondeterministic polynomial time, or else the polynomial-time hierarchy from exponential time.We also look at the autoreducibility of complete sets under nonadaptive, bounded query, probabilistic, and nonuniform reductions. We show how settling some of these autoreducibility questions will also lead to new complexity class separations.
Studying programmer behavior experimentally: the problems of proper methodology
Authors: Ruven E. Brooks
Venue: Communications of the ACM (1980)

The application of behavioral or psychological techniques to the evaluation of programming languages and techniques is an approach which has found increased applicability over the past decade. In order to use this approach successfully, investigators must pay close attention to methodological issues, both in order to insure the generalizability of their findings and to defend the quality of their work to researchers in other fields. Three major areas of methodological concern, the selection of subjects, materials, and measures, are reviewed. The first two of these areas continue to present major difficulties for this type of research.
Hierarchical binary search
Authors: Arthur Gill
Venue: Communications of the ACM (1980)

In hierarchical search the data structure holding the file keys is partitioned into substructures of the same type; these are searched consecutively until the queried key is found or the substructures are exhausted. The interest here is in the conditions under which the performance of a hierarchical organization of static files is superior to that of the nonhierarchical organization and in the construction of the hierarchy when these conditions are met. The performance criterion is the average number of comparisons in a successful search, where averaging extends over all keys and over all permutations of the key's access probabilities. General properties of hierarchical search are first derived, and attention is then focused on the hierarchical binary organization&mdash;the special case where each of the data substructures is a sorted array (or a balanced binary tree) and where the keys are accessed by binary search. It is shown that an advantageous two-stage hierarchy is always implementable when the keys' access density function &phgr;(i) is &ldquo;steeper&rdquo; than Zipf's density function &zgr;(i)&mdash;the steeper it is, the greater the advantage. A simple method for constructing the two-stage hierarchy is formulated, based on finding the intersection of &phgr;(i) and &zgr;(i). For the r-stage hierarchical organization, partitioning procedures are proposed which are based on the iterative application of the two-stage techniques.
The Puzzle of 3D Graphics on Linux
Authors: John Matthews Daryll Strauss
Venue: Linux Journal (2000)

From OpenGL to DRI to DGA, each term refers to a particular part of the full scene of Linux graphics.
Measuring participants' perception on facilitation in group support systems meetings
Authors: Gert-Jan de Vreede, Fred Niederman, Ilse Paarlberg
Venue: Proceedings of the 2001 ACM SIGCPR conference on Computer personnel research (2001)

Facilitation is often considered to be one of the key factors in the successful application of Group Support Systems. Research on GSS facilitation has revealed insight into the types of tasks performed by facilitators and the potential positive effects of facilitation on group consensus and satisfaction. However, earlier research has hardly approached GSS facilitation from the participants' point of view. This paper presents a study in which a questionnaire was developed and distributed to 182 participants of facilitated GSS meeting in order to measure their perception on various facilitation tasks. The results suggested three categories of facilitation tasks that are perceived important by participants. Each of these categories strongly correlated with participants' meeting satisfaction. Further research is needed to refine these categories so that the instrument may be used to evaluate a facilitator's performance.
Concurrent garbage collection using hardware-assisted profiling
Authors: Timothy H. Heil, James E. Smith
Venue: Proceedings of the 2nd international symposium on Memory management (2000)

In the presence of on-chip multithreading, a Virtual Machine (VM) implementation can readily take advantage of service threads for enhancing performance by performing tasks such as profile collection and analysis, dynamic optimization, and garbage collection concurrently with program execution. In this context, a hardware-assisted profiling mechanism is proposed. The Relational Profiling Architecture (RPA) is designed from the top down. RPA is based on a relational model similar to the relational database model. Instructions selected for profiling produce a record of information. A simple query engine examines these records for patterns, and performs simple actions on matching records. The power and flexibility of RPA is demonstrated by developing a concurrent generational garbage collector for Java. Detailed execution driven simulations show that this collector has an average runtime overhead of approximately 0.6%. The short pauses in the application required for synchronization with the garbage collector are at most 54 microseconds, given a 1GHz clock frequency.
Balancing binary trees by internal path reduction
Authors: Gaston H. Gonnet
Venue: Communications of the ACM (1983)

We present an algorithm for balancing binary search trees. In this algorithm single or double rotations are performed when they decrease the internal path of the total tree. It is shown that the worst internal path on such trees is never more than 5 percent worse than optimal and that its height is never more than 44 percent taller than optimal. This compares favorably with the AVL trees whose internal path may be 28 percent worse than optimal and the same 44 percent worst height, and with the weight-balanced trees which may be 15 and 100 percent worse than optimal, respectively. On the other hand, the number of rotations during a single insertion/deletion can be O(n), although the amortized worst-case number of rotations is O(log n) per update.
A LAN emulation model for wireless ATM
Authors: Anna Hać Asif Hossain
Venue: International Journal of Network Management (2001)

An architecture based on emulated LAN is proposed which can efficiently provide the required bandwidth of mobiles as they migrate between cells. The proposed solution &lpar;1&rpar; ensures the required bandwidth of a mobile when its path changes because of handoff, &lpar;2&rpar; efficiently reserves bandwidth resulting in higher bandwidth&sol;network utilization, &lpar;3&rpar; has the flexibility of reserving bandwidth depending upon the mobility &lpar;rate of handoff&rpar;. Copyright &copy; 2001 John Wiley Sons, Ltd.
From Washington: Secrecy versus scientific communication
Authors: Rosalie Steier
Venue: Communications of the ACM (1983)

There are many issues that affect the health of science but none more pervasive than the problem of &ldquo;secrecy vs. scientific communication.&rdquo; Unfortunately much of the debate on this issue, which is concern to all scientists, is being held behind closed doors among a few &ldquo;key people.&rdquo; The status of this debate was discussed in the August issue of Communications. More recent developments are reviewed here. The ACM Portal is published by the Association for Computing Machinery. Copyright © 2010 ACM, Inc. Terms of Usage Privacy Policy Code of Ethics Contact Us Useful downloads: Adobe Acrobat QuickTime Windows Media Player Real Player
As the Log Scrolls By...
Authors: Gaelyne R. Gasson
Venue: Linux Journal (2001)

Gasson shows how a few tweaks to Apache's httpd.conf file can provide a colorful web log file.
An exponential method for the solution of systems of ordinary differential equations
Authors: Sherwood C. Chu, Mones Berman
Venue: Communications of the ACM (1974)

An explicit, coupled, single-step method for the numerical solution of initial value problems for systems of ordinary differential equations is presented. The method was designed to be general purpose in nature but to be especially efficient when dealing with stiff systems of differential equations. It is, in general, second order except for the case of a linear system with constant coefficients and linear forcing terms; in that case, the method is third order. It has been implemented and put to routine usage in biological applications&mdash;where stiffness frequently appears&mdash;with favorable results. When compared to a standard fourth order Runge-Kutta implementation, computation time required by this method has ranged from comparable for certain nonstiff problems to better than two orders of magnitude faster for some highly stiff systems.