ppxscal/embedding_network huggingface dataset:
Effective distributed scheduling of parallel workloads
Authors: Andrea C. Dusseau, Remzi H. Arpaci, David E. Culler
Venue: Proceedings of the 1996 ACM SIGMETRICS international conference on Measurement and modeling of computer systems (1996)

We present a distributed algorithm for time-sharing parallel workloads that is competitive with coscheduling. Implicit scheduling allows each local scheduler in the system to make independent decisions that dynamically coordinate the scheduling of cooperating processes across processors. Of particular importance is the blocking algorithm which decides the action of a process waiting for a communication or synchronization event to complete. Through simulation of bulk-synchronous parallel applications, we find that a simple two-phase fixed-spin blocking algorithm performs well; a two-phase adaptive algorithm that gathers run-time data on barrier wait-times performs slightly better. Our results hold for a range of machine parameters and parallel program characteristics. These findings are in direct contrast to the literature that states explicit coscheduling is necessary for fine-grained programs. We show that the choice of the local scheduler is crucial, with a priority-based scheduler performing two to three times better than a round-robin scheduler. Overall, we find that the performance of implicit scheduling is near that of coscheduling (+/- 35%), without the requirement of explicit, global coordination.
Sharing the &ldquo;cost&rdquo; of multicast trees: an axiomatic analysis
Authors: Shai Herzog, Scott Shenker, Deborah Estrin
Venue: ACM SIGCOMM Computer Communication Review (1995)

Given the need to provide users with reasonable feedback about the "costs" their network usage incurs, and the increasingly commercial nature of the Internet, we believe that the allocation of cost among users will play an important role in future networks. This paper discusses cost allocation in the context of multicast flows. The question we discuss is this: when a single data flow is shared among many receivers, how does one split the cost of that flow among the receivers? Multicast routing increases network efficiency by using a single shared delivery tree. We address the issue of how these savings are allocated among the various members of the multicast group. We first consider an axiomatic approach to the problem, analyzing the implications of different distributive notions on the resulting allocations. We then consider a one-pass mechanism to implement such allocation schemes and investigate the family of allocation schemes such mechanisms can support.
Small-Sample Statistical Estimates for Matrix Norms
Authors: T. Gudmundsson, C. S. Kenney, A. J. Laub
Venue: SIAM Journal on Matrix Analysis and Applications (1995)

This paper extends a recent statistically based vector-norm estimator to matrices. The new estimator requires only a few matrix-vector multiplications and can be applied when the matrix is not known explicitly. It is useful for efficiently estimating the sensitivity of vector-valued functions and can be applied to many problems where the power method runs into difficulties. Lower bounds for the probability that an estimate is within a given factor of the correct norm are derived. These bounds are straightforward to compute and show that a very inaccurate estimate is extremely unlikely in most cases. A conservative lower bound has been derived and a tighter bound is given in the form of a conjecture. This conjecture is true in some important special cases and the general case is supported by considerable empirical evidence.
The dangers of replication and a solution
Authors: Jim Gray, Pat Helland, Patrick O'Neil, Dennis Shasha
Venue: Proceedings of the 1996 ACM SIGMOD international conference on Management of data (1996)

Update anywhere-anytime-anyway transactional replication has unstable behavior as the workload scales up: a ten-fold increase in nodes and traffic gives a thousand fold increase in deadlocks or reconciliations. Master copy replication (primary copy) schemes reduce this problem. A simple analytic model demonstrates these results. A new two-tier replication algorithm is proposed that allows mobile (disconnected) applications to propose tentative update transactions that are later applied to a master copy. Commutative update transactions avoid the instability of other replication schemes.
Information systems skills: achieving alignment between the curriculum and the needs of the IS professionals in the future
Authors: Eugenia M. W. Ng Tye, Ray S. K. Poon, Janice M. Burn
Venue: ACM SIGMIS Database (1995)

The objectives of this study are to find out the perceived information systems (IS) skills which are important at present and in five years time, and the perceived emphasis of IS curricula on these skills. It is found that the scope of skills required of IS professionals will broaden towards the end of the decade. Interpersonal skills, business skills, analysis and design skills, and programming skills are the most critical for career development. Results also show that there is a match between the skills and knowledge possessed by IS graduates of the Hong Kong Polytechnic University and industry requirements for the current IS environment. However, the curriculum is not aligned with industry needs in the future. This indicates that the education the respondents received does not prepare them for progression up the career ladder. Implications of the findings are discussed so that a new curriculum may be designed to provide the preferred IS graduates to industry.
Approximate Feedback Linearization: A Homotopy Operator Approach
Authors: Andrzej Banaszuk, John Hauser
Venue: SIAM Journal on Control and Optimization (1996)

In this paper, we present an approach for finding feedback linearizable systems that approximate a given single-input nonlinear system on a given compact region of the state space. First, we show that if the system is close to being involutive, then it is also close to being linearizable. Rather than working directly with the characteristic distribution of the system, we work with characteristic one-forms, i.e., with the one-forms annihilating the characteristic distribution. We show that homotopy operators can be used to decompose a given characteristic one-form into an exact and an antiexact part. The exact part is used to define a change of coordinates to a normal form that looks like a linearizable part plus nonlinear perturbation terms. The nonlinear terms in this normal form depend continuously on the antiexact part, and they vanish whenever the antiexact part does. Thus, the antiexact part of a given characteristic one-form is a measure of nonlinearizability of the system. If the nonlinear terms are small, by neglecting them we obtain a linearizable system approximating the original system. One can design control for the original system by designing it for the approximating linearizable system and applying it to the original one. We apply this approach for design of locally stabilizing feedback laws for nonlinear systems that are close to being linearizable.
System level verification of video and image processing specifications
Authors: H. Samsom, F. Franssen, F. Catthoor, H. De Man
Venue: Proceedings of the 8th international symposium on System synthesis (1995)

Abstract: A formal verification method is presented to verify the loop ordering of a high level transformed description against its original specification. The verification is done in an automatic way and its complexity is independent on the sizes of the loops bounds. Any practical structure of loop nests can be handled. The method is especially suited for applications in the area of speech, image and video processing, front-end telecom and numerical computing systems which exhibit many loops and complex multi-dimensional signals. The efficiency of the approach is demonstrated on several realistic examples.
A formalization of the Turing test
Authors: Phillip G. Bradford, Michael Wollowski
Venue: ACM SIGART Bulletin (1995)

Alan Turing proposed an interactive test to replace the question "Can machines think?" This test has become known as the Turing Test and its validity for determining intelligence or thinking is still in question.Struggling with the validity of long proofs, program correctness, computational complexity and cryptography, theoreticians developed interactive proof systems. By formalizing the Turing Test as an interactive proof system and by employing results from complexity theory, this paper investigates the power and limitations of the Turing Test. In particular, assuming the notion of completeness for standard complexity classes carries over faithfully to human cognition, then we can say: if human intelligence subsumes machine intelligence, and human intelligence is not simulatable by any bounded machine, then the Turing Test can distinguish humans and machines to within arbitrarily high probability.This paper makes no claim about the Turing Test's sufficiency to distinguish humans and machines. Rather, through its formalization this paper gives several ramifications involving the acceptance or rejection of the Turing Test as sufficient for making any such distinction.
Some Remarks Concerning Iterative Methods for Linear Systems
Authors: Fred B. Weissler
Venue: SIAM Journal on Matrix Analysis and Applications (1995)

Let $A$ be a Hermitian, positive definite matrix. It is well known that if $A = M - N$, where $M$ is invertible and $M* + N$ is also positive definite, then the iterative method for solving $Au = b$, based on this decomposition, is convergent. A new proof of this convergence is given, providing an explicit estimate for the spectral radius of $M^{-1}N$. Also, a new method to estimate the optimal relaxation parameter for certain large matrices is suggested.
Internet-accessible information retrieval tools for advanced DB/IR courses
Authors: Sally Jo Cunningham
Venue: ACM SIGCSE Bulletin (1996)

A number of information retrieval tools are now freely available over the Internet, either as full production programs or demos. These programs illustrate a wide variety of IR techniques, and can allow students to gain realistic, hands-on experience with a variety of algorithms that were previously difficult to discuss other than in theory. In addition, many of these programs are associated with computing-related document collections that in and of themselves are useful for computer science students.
A survey of linear programming in randomized subexponential time
Authors: Michael Goldwasser
Venue: ACM SIGACT News (1995)

Three papers were published in 1992, each providing a combinatorial, randomized algorithm solving linear programming in subexponential expected time. Bounds on independent algorithms were proven, one by Kalai, and the other by Matousek, Sharir, and Welzl. Results by G auml;rtner combined techniques from these papers to solve a much more general optimization problem in similar time bounds.Although the algorithms by Kalai and Sharir-Welzl seem remarkably different in style and evolution, this paper demonstrates that one of the variants of Kalai's algorithm is identical (although dual) to the algorithm of Sharir-Welzl. Also the implication of G auml;rtner's framework on future improvements is examined more carefully.
Sorting with self-organizing maps
Authors: Marco Budinich
Venue: Neural Computation (1995)

A self-organizing feature map (Von der Malsburg 1973; Kohonen 1984) sorts n real numbers in O(n) time apparently violating the O(n log n) bound. Detailed analysis shows that the net takes advantage of the uniform distribution of the numbers and, in this case, sorting in O(n) is possible. There are, however, an exponentially small fraction of pathological distributions producing O(n2) sorting time. It is interesting to observe that standard learning produced a smart sorting algorithm.
Active Camera Calibration for a Head-Eye Platform Using the Variable State-Dimension Filter
Authors: Philip F. McLauchlan, David W. Murray
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1996)

This correspondence presents a new technique for calibrating a camera mounted on a controllable head/eye platform. It uses the trajectories of an arbitrary number of tracked corner features to improve the calibration parameter estimates over time, utilizing a novel variable state dimension form of recursive filter. No special visual stimuli are required and no assumptions are made about the structure of the scene, other than that it is stationary relative to the head. The algorithm runs at 4 frames per second on a single Inmos T805 transputer, and is fully integrated into a real-time active vision system. Updated calibration parameters are regularly passed to the vision modules that require them. Although the algorithm requires an initial estimate of camera focal length, results are presented from real experiments demonstrating that convergence is achieved for initial errors up to 50%.
Canonical Encoders for Sliding Block Decoders
Authors: Jonathan Ashley, Brian Marcus
Venue: SIAM Journal on Discrete Mathematics (1995)

The existence and uniqueness of a canonical minimal encoder for any given sliding block decoder are proven. The structure of this encoder is given in terms of an explicit sequence of state splittings. The universality of the state splitting algorithm for code construction is clarified.
A provable time and space efficient implementation of NESL
Authors: Guy E. Blelloch, John Greiner
Venue: Proceedings of the first ACM SIGPLAN international conference on Functional programming (1996)

In this paper we prove time and space bounds for the implementation of the programming language NESL on various parallel machine models. NESL is a sugared typed lambda;-calculus with a set of array primitives and an explicit parallel map over arrays. Our results extend previous work on provable implementation bounds for functional languages by considering space and by including arrays. For modeling the cost of NESL we augment a standard call-by-value operational semantics to return two cost measures: a DAG representing the sequential dependence in the computation, and a measure of the space taken by a sequential implementation. We show that a NESL program with w work (nodes in the DAG), d depth (levels in the DAG), and s sequential space can be implemented on a p processor butterfly network, hypercube, or CRCW PRAM using O(w/p + d log p) time and O(s + dp log p) reachable space.1 For programs with sufficient parallelism these bounds are optimal in that they give linear speedup and use space within a constant factor of the sequential space.
Simple and effective analysis of statically-typed object-oriented programs
Authors: Amer Diwan, J. Eliot B. Moss, Kathryn S. McKinley
Venue: ACM SIGPLAN Notices (1996)

To use modern hardware effectively, compilers need extensive control-flow information. Unfortunately, the frequent method invocations in object-oriented languages obscure control flow. In this paper, we describe and evaluate a range of analysis techniques to convert method invocations into direct calls for statically-typed object-oriented languages and thus improve control-flow information in object-oriented languages. We present simple algorithms for type hierarchy analysis, aggregate analysis, and interprocedural and intraprocedural type propagation. These algorithms are also fast, O(|procedures| * sum;pprocedure np * vp) worst case time (linear in practice) for our slowest analysis, where np is the size of procedure p and vp is the number of variables in procedure p, and are thus practical for use in a compiler. When they fail, we introduce cause analysis to reveal the source of imprecision and suggest where more powerful algorithms may be warranted. We show that our simple analyses perform almost as well as an oracle that resolves all method invocations that invoke only a single procedure.
Integrating multiple descriptions in simulation model design: a knowledge based approach
Authors: Natarajan Padmanaban, Perakath C. Benjamin, Richard J. Mayer
Venue: Proceedings of the 27th conference on Winter simulation (1995)

Because manufacturing and business systems are complex systems encompassing different sub-systems and because different domain experts design, implement, and maintain these sub-systems, it is becoming imperative that descriptions from different domain experts are captured, stored, and used to design realistic simulation models of manufacturing systems. This paper presents the concept of multiple descriptions and its applicability in manufacturing systems modeling and simulation and presents a knowledge based approach to support the integration of multiple descriptions in designing valid simulation models.
User responses to constraints in computerized design tools (extended abstract)
Authors: Donald L. Day
Venue: ACM SIGSOFT Software Engineering Notes (1996)

This study sought to improve our understanding of user attitudes, perceptions, satisfaction and behavior in reference to constraints within computerized design tools. It also attempted to examine the differences in perspective between tool builders and tool users regarding appropriate design practices, as communicated via design tools.The study created a typology of constraints and described a set of strategies users employ in the negotiation of constraints encountered in of computer-aided systems engineering (CASE) tools. Also addressed were (a) the cognitive fit between tool users and tool builders in terms of appropriate and necessary constraints, and (b) issues of creativity in the design of computer software.An eight-page questionnaire containing 61 questions was developed by conducting structured interviews with tool users and managers, in industry. Following a pre-test, the questionnaire was administered to an international sample of tool users, tool builders and non-CASE software application developers (a control group). More than 200 questionnaires were returned (half via electronic mail) from respondents largely in North America, but also from Europe, Australia and New Zealand.Analysis followed a factorial design that evaluated the impact of normative attitudes toward and perceptions of control upon satisfaction and behavior. Most respondents reported not feeling especially encumbered with constraints in their tools, although most also reserved the right to override or work around constraints, depending upon circumstances.The study found that normative attitudes toward control have a significant impact upon behavior in response to constraints in computerized design tools. (Favorable attitudes toward control are associated significantly with conforming behavior.) It also found that perceptions of control have a significant impact upon satisfaction and behavior. (Perceptions of high control are associated significantly with low satisfaction and with resistant behavior.) No significant differences were observed between tool users and tool builders in terms of key constructs.Suggestions for future research include investigation of concerns raised by the current study, examination of similar effects in other domains (such as architectural design), and development of the potential for intelligent machine guidance in creative design activities.
APT: a data structure for optimal control dependence computation
Authors: Keshav Pingali, Gianfranco Bilardi
Venue: ACM SIGPLAN Notices (1995)

The control dependence relation is used extensively in restructuring compilers. This relation is usually represented using the control dependence graph; unfortunately, the size of this data structure can be quadratic in the size of the program, even for some structured programs. In this paper, we introduce a data structure called the augmented post-dominator tree (APT) which is constructed in space and time proportional to the size of the program, and which can answer control dependence queries in time proportional to the size of the output. Therefore, APT is an optimal representation of control dependence. We also show that using APT, we can compute SSA graphs, as well as sparse dataflow evaluator graphs, in time proportional to the size of the program. Finally, we put APT in perspective by showing that it can be viewed as a factored representation of control dependence graph in which filtered search is used to answer queries.
Empirical evaluation of the CRAY-T3D: a compiler perspective
Authors: Remzi H. Arpaci, David E. Culler, Arvind Krishnamurthy, Steve G. Steinberg, Katherine Yelick
Venue: ACM SIGARCH Computer Architecture News (1995)

Most recent MPP systems employ a fast microprocessor surrounded by a shell of communication and synchronization logic. The CRAY-T3D provides an elaborate shell to support global-memory access, prefetch, atomic operations, barriers, and block transfers. We provide a detailed empirical performance characterization of these primitives using micro-benchmarks and evaluate their utility in compiling for a parallel language. We have found that the raw performance of the machine is quite impressive and the most effective forms of communication are prefetch and write. Other shell provisions, such as the bulk transfer engine and the external Annex register set, are cumbersome and of little use. By evaluating the system in the context of a language implementation, we shed light on important trade-offs and pitfalls in the machine architecture.
Optimally Weighted MUSIC for Frequency Estimation
Authors: Petre Stoica, Anders Eriksson, Torsten Soderstrom
Venue: SIAM Journal on Matrix Analysis and Applications (1995)

This paper introduces a weighted MUSIC (multiple signal classification) algorithm for estimating the frequencies of sinusoidal signals from noise-corrupted measurements. The large-sample variance of the weighted MUSIC is determined, and the optimal weighting matrix which minimizes that variance is derived. The optimally weighted MUSIC is shown to provide more accurate frequency estimates than the unweighted MUSIC and ESPRIT (estimation of signal parameters via rotation invariance techniques).
Formal specification and design of a message router
Authors: Christian Creveuil, Gruia-Catalin Roman
Venue: ACM Transactions on Software Engineering and Methodology (TOSEM) (1994)

Formal derivation refers to a family of design techniques that entail the development of programs which are guaranteed to be correct by construction. Only limited industrial use of such techniques (e.g., UNITY-style specification refinement) has been reported in the literature, and there is a great need for methodological developments aimed at facilitating their application to complex problems. This article examines the formal specification and design of a message router in an attempt to identify those methodological elements that are likely to contribute to successful industrial uses of program derivation. Although the message router cannot be characterized as being industrial grade, it is a sophisticated problem that poses significant specification and design challenges&mdash;its apparent simplicity is rather deceiving. The main body of the article consists of a complete formal specification of the router and a series of successive refinements that eventually lead to an immediate construction of a correct UNITY program. Each refinement is accompanied by its design rationale and is explained in a manner accessible to a broad audience. We use this example to make the case that program derivation provides a good basis for introducing rigor in the design strategy, regardless of the degrees of formality one is willing to consider.