ppxscal/embedding_network huggingface dataset:
Combinatorial techniques for universal hashing
Authors: D. R. Stinson
Venue: Journal of Computer and System Sciences (1994)

The idea of a universal class of hash functions is due to Carter and Wegman. The goal is to define a collection of hash functions in such a way that a random choice of a function in the class yields a low probability that any two distinct inputs will collide. In this paper, we present some characterizations of universal classes of hash functions in terms of combinatorial designs such as resolvable balanced incomplete block designs and orthogonal arrays. The two classes of hash functions that we study are called optimally universal and strongly universal. We show that optimally universal classes of hash functions are equivalent to resolvable balanced incomplete block designs and strongly universal classes are equivalent to orthogonal arrays. Consequently, known classes of combinatorial designs yield new, small, and efficient classes of universal hash functions.
Optimal evaluation of array expressions on massively parallel machines (extended abstract)
Authors: Siddhartha Chatterjee, John R. Gilbert, Robert Schreiber, Shang-Hua Teng
Venue: ACM SIGPLAN Notices (1993)

We investigate the problem of optimal evaluation of Fortran-90 style array expressions on a massively parallel distributed-memory machine. On such machines, an elementwise operation can be performed in unit time for arrays whose corresponding elements are in the same processor. If the arrays are not aligned in this manner, the cost of alignment is part of the cost of expression evaluation. The choice of where to perform the operation then affects this cost. We demonstrate how a dynamic programming technique can be applied to solve this problem efficiently for a wide variety of interconnection schemes, including multidimensional grids and rings, hypercubes, and fat-trees. We also consider the variant where the operations may change the shape of the arrays, and show that our approach extends naturally to handle this case.
On the lattice structure of the add-with-carry and subtract-with-borrow random number generators
Authors: Shu Tezuka, Pierre L'Ecuyer, Raymond Couture
Venue: ACM Transactions on Modeling and Computer Simulation (TOMACS) (1993)

Marsaglia and Zaman recently proposed new classes of random number generators, called add-with-carry(AWC) and subtract-with-borrow(SWB), which are capable of quickly generating very long-period (pseudo)-random number sequences using very little memory. We show that these sequences are essentially equivalent to linear congruential sequences with very large prime moduli. So, the AWC/SWB generators can be viewed as efficient ways of implementing such large linear congruential generators. As a consequence, the theoretical properties of such generators can be studied in the same way as for linear congruential generators, namely, via the spectral and lattice tests. We also show how the equivalence can be exploited to implement efficient jumping-ahead facilities for the AWC and SWB sequences. Our numerical examples illustrate the fact that AWC/SWB generators have extremely bad lattice structure in high dimensions.
Evicted variables and the interaction of global register allocation and symbolic debugging
Authors: Ali-Reza Adl-Tabatabai, Thomas Gross
Venue: Proceedings of the 20th ACM SIGPLAN-SIGACT symposium on Principles of programming languages (1993)

A symbolic debugger allows a user to display the values of program variables at a breakpoint. However, problems arise if the program is translated by an optimizing compiler. This paper addresses the effects of global register allocation and assignment: a register assigned to a variable V may not be holding V's value at a breakpoint since the register can also be assigned to other variables. We define the problem of determining whether a variable is in its assigned register as the residence problem. Prior work on debugging of optimized code has focused on the currency problem; detecting whether a variable's run-time value is the expected value. Determining residence is a more serious problem than currency detection. We present a data flow algorithm that accurately computes a variable's residency, by determining when a variable becomes evicted from its register. We measure the effectiveness of different approaches to determine variable residence for three C programs from the SPEC suite.
How to move (physically speaking) in a multi-agent world (abstract)
Authors: Jean-Claude Latombe
Venue: ACM SIGOIS Bulletin (1992)

We consider the case of a physical agent (e.g., a robot) who accomplishes tasks by moving in a physical world populated by other physical agents. We discuss various approaches for planning the motions of such an agent. These approaches range between two extremes. At one extreme, the agent is a super-agent that plans the coordinated motions of all the other agents. At the other extreme, the agent deals with the other agents as if they were unexpected moving obstacles detected through sensors during the execution of motion plans. Between these two extremes, many other approaches are possible by engineering and combining basic motion planning methods (and higher-level reasoning methods) in different ways. These approaches differ in the amont of prior knowledge and the nature of inter-agent communication they require, as well as in their completeness, computational complexity, and their tolerance to unexpectedness. If a truly autonomous agent in a multi-agent world is to be eventually built, it is very likely that it will have to embed several of these approaches.
Optimizing file transfer response time using the loss-load curve congestion control mechanism
Authors: Carey L. Williamson
Venue: ACM SIGCOMM Computer Communication Review (1993)

Loss-load curves are a recently proposed feedback mechanism for rate-based congestion control in datagram computer networks. In the loss-load model, packet loss inside the network is a direct function of sender transmission rates, and senders have the responsibility of choosing their own transmission rate based on the loss-load tradeoff curve provided by the network. Earlier work has provided the mathematical basis for the loss-load model and provided preliminary simulation results demonstrating its responsiveness, fairness, and stability. The loss-load model works well for simple network environments where each source has many packets to transmit, and wishes to maximize raw throughput.In this paper, the applicability of loss-load curves is extended to senders with more general network traffic requirements, such as file transfer activities. In particular, the paper considers senders wishing to minimize the response time for a transfer of N packets. When N is small, a sender chooses a low transmission rate, to minimize the probability of packet loss. When N is large, a higher transmission rate is chosen to increase raw throughput. The loss-load curve mechanism provides necessary and sufficient information for senders at the edges of the network to choose a proper transmission rate based on their traffic requirements and the current network load.Simulation results show that the loss-load mechanism is effective in achieving high network utilization and minimizing response time for file transfers. The loss-load model also does a good job of providing equitable service to senders with different traffic workloads and different round trip times.
Unicity of Biproportion
Authors: Louis de Mesnard
Venue: SIAM Journal on Matrix Analysis and Applications (1994)

The biproportion of $S$ on margins of $M$ is called the intern composition law, $K:(S,M)\mapsto X = K(S,M)/X = ASB$. $A$ and $B$ are diagonal matrices, algorithmically computed, providing the respect of margins of $M$. Biproportion is an empirical concept. In this paper, the author shows that any algorithm used to compute a biproportion leads to the same result. Then the concept is unique and no longer empirical. Some special properties are also indicated.
Competitive k-server algorithms
Authors: Amos Fiat, Yuval Rabani, Yiftach Ravid
Venue: Journal of Computer and System Sciences (1994)

In this paper we give deterministic competitive k-server algorithms for all k and all metric spaces. This settles the k-server conjecture up to the competitive ratio. The best previous result for general metric spaces was a three-server randomized competitive algorithm and a non-constructive proof that a deterministic three-server competitive algorithm exists. The competitive ratio we can prove is exponential in the number of servers. Thus, the question of the minimal competitive ratio for arbitrary metric spaces is still open.
The variance of covariance rules for associative matrix memories and reinforcement learning
Authors: Peter Dayan, Terrence J. Sejnowski
Venue: Neural Computation (1993)

Hebbian synapses lie at the heart of most associative matrix memories (Kohonen 1987; Hinton and Anderson 1981) and are also biologically plausible (Brown et al. 1990; Baudry and Davis 1991). Their analytical and computational tractability make these memories the best understood form of distributed information storage. A variety of Hebbian algorithms for estimating the covariance between input and output patterns has been proposed. This note points out that one class of these involves stochastic estimation of the covariance, shows that the signal-to-noise ratios of the rules are governed by the variances of their estimates, and considers some parallels in reinforcement learning.
What is a solution of an ODE?
Authors: Robert M. Corless
Venue: ACM SIGSAM Bulletin (1993)

This article will introduce a nonstandard definition of the 'solution' of an ordinary differential equation (ODE). I hope that this article will start some discussion; further, I hope that this article will have some effect on the ambitious European CATHODE project, which is attempting to provide tools in computer algebra for handling ordinary differential equations.
Reversibility and surjectivity problems of cellular automata
Authors: Jarkko Kari
Venue: Journal of Computer and System Sciences (1994)

The problem of deciding if a given cellular automaton (CA) is reversible (or, equivalently, if its global transition function is injective) is called the reversibility problem of CA. In this article we show that the reversibility problem is undecidable in case of two-dimensional CA. We also prove that the corresponding surjectivity problem-the problem of deciding if the global function is surjective-is undecidable for two-dimensional CA. Both problems are known to be decidable in case of one-dimensional CA. The proofs of the theorems are based on reductions from the well-known tiling problem of the plane, known also as the domino problem.
Empirical performance evaluation of concurrency and coherency control protocols for database sharing systems
Authors: Erhard Rahm
Venue: ACM Transactions on Database Systems (TODS) (1993)

Database Sharing (DB-sharing) refers to a general approach for building a distributed high performance transaction system. The nodes of a DB-sharing system are locally coupled via a high-speed interconnect and share a common database at the disk level. This is also known as a &ldquo;shared disk&rdquo; approach. We compare database sharing with the database partitioning (shared nothing) approach and discuss the functional DBMS components that require new and coordinated solutions for DB-sharing. The performance of DB-sharing systems critically depends on the protocols used for concurrency and coherency control. The frequency of communication required for these functions has to be kept as low as possible in order to achieve high transation rates and short response times. A trace-driven simulation system for DB-sharing complexes has been developed that allows a realistic performance comparison of four different concurrency and coherency control protocols. We consider two locking and two optimistic schemes which operate either under central or distributed control. For coherency control, we investigate so-called on-request and broadcast invalidation schemes, and employ buffer-to-buffer communication to exchange modified pages directly between different nodes. The performance impact of random routing versus affinity-based load distribution and different communication costs is also examined. In addition, we analyze potential performance bottlenecks created by hot spot pages.
Accurate Downdating of Least Squares Solutions
Authors: A. Bjorck, H. Park, L. Elden
Venue: SIAM Journal on Matrix Analysis and Applications (1994)

Solutions to a sequence of modified least squares problems, where either a new observation is added (updating) or an old observation is deleted (downdating), are required in many applications. Stable algorithms for downdating can be constructed if the complete QR factorization of the data matrix is available. Algorithms that only downdate $R$ and do not store $Q$ require less operations. However, they do not give good accuracy and may not recover accuracy after an ill-conditioned problem has occurred. The authors describe a new algorithm for accurate downdating of least squares solutions and compare it to existing algorithms. Numerical test results are also presented using the sliding window method, where a number of updatings and downdatings occur repeatedly.
The design of floating-point data types
Authors: David Goldberg
Venue: ACM Letters on Programming Languages and Systems (LOPLAS) (1992)

The issues involved in designing the floating-point part of a programming language are discussed. Looking at the language specifications for most existing languages might suggest that this design involves only trivial issues, such as whether to have one or two types of REALs or how to name the functions that convert from INTEGER to REAL. It is shown that there are more significant semantic issues involved. After discussing the trade-offs for the major design decisions, they are illustrated by presenting the design of the floating-point part of the Modula-3 language.
IS strategy and implementation: a case study of a building society
Authors: Geoff Walsham
Venue: ACM SIGOIS Bulletin (1993)

This short paper concerns the strategy, development and implementation of computer-based information systems in a medium-sized U.K. building society during the period 1981 to 1987. The Society experienced a dramatic improvement in its financial performance during the period under the leadership of its Chief Executive, with IS being central to the changes which took place. An outline case history is presented here, followed by some formal analysis of the case in terms of social context and process. Some conclusions are drawn on whether users 'got what they wanted' in this case, and on whether this is an appropriate focus for the development of information systems in organizations.A much fuller description and analysis of this case, including a later two-year period under a new Chief Executive, is given in the book referenced at the end of this paper.
The ripple effect
Authors: Geoff Harris, John Forster, Richard Rankin
Venue: ACM SIGICE Bulletin (1994)

A brief overview of research to date on word games in general, and crossword puzzle solution algorithms in particular, is presented. An algorithm which is easy to implement and is highly suited for PC work-stations is presented. An implementation of this algorithm is demonstrated to produce dramatic reductions of the size of the search trees traversed by specific crossword puzzle implementations.
Continuations without copying
Authors: Scott L. Burson
Venue: ACM SIGPLAN Notices (1994)

Common implementations of first-class continuations for Scheme involve copying the continuation when it is captured, when it is invoked, or both. Standard ML of New Jersey, on the other hand, creates all continuation frames in the heap to begin with; this eliminates the copying required for capture and invocation, but also gives up the optimization of using the "stack pop" operation to deallocate frames that have not been captured. In this paper, we show how to eliminate both copying steps while retaining efficient stack-wise deallocation for uncaptured flames.
Integration of DCE and local registries: design approaches
Authors: Ping Lin, Sekar Chandersekaran
Venue: Proceedings of the 1st ACM conference on Computer and communications security (1993)

When DCE is implemented on an existing operating system platform, its security facilities need to be integrated with the local security facilities on that platform. One key task in this effort is the integration of the DCE registry and the local security registry. This paper discusses the requirement for registry integration, and considers alternative approaches to a number of major structural issues that arise when integrating the DCE registry with local registries, including:The relationship of the DCE registry with respect to the local registriesPropagation of updates to local registriesSelectivity of update propagation&ldquo;Push&rdquo; versus &ldquo;pull&rdquo; of updates&ldquo;Write-through&rdquo; versus &ldquo;virtual update&rdquo;.
A sort inference algorithm for the polyadic &pgr;-calculus
Authors: Simon J. Gay
Venue: Proceedings of the 20th ACM SIGPLAN-SIGACT symposium on Principles of programming languages (1993)

In Milner's polyadic &pgr;-calculus there is a notion of sorts which is analogous to the notion of types in functional programming. As a well-typed program applies functions to arguments in a consistent way, a well-sorted process uses communication channels in a consistent way. An open problem is whether there is an algorithm to infer sorts in the &pgr;-calculus in the same way that types can be inferred in functional programming. Here we solve the problem by presenting an algorithm which infers the most general sorting for a process in the first-order calculus, and proving its correctness. The algorithm is similar in style to those used for Hindley-Milner type inference in functional languages.
Computational Methods in Transient Electromagnetics: A Selective Survey
Authors: Griffin K. Gothard, Douglas A. Vechinski, Sadasiva M. Rao
Venue: IEEE Computational Science Engineering (1994)

We can now solve real-life problems in electromagnetics at all levels of complexity. Several popular algorithms are available to deal with the transient-scattering problem. They all solve either differential or integral equations in one form or another. No one method is best in all situations. Since only differential or integral equations are involved in the final solution, the methods described in this paper should be of considerable interest to other areas of science as well. Each of the methods available for predicting transient behaviors and responses has certain advantages and disadvantages, so an approach must be chosen carefully, depending on the problem complexity.
A constructive logic of multiple subtyping
Authors: Harry G. Mairson
Venue: Proceedings of the 20th ACM SIGPLAN-SIGACT symposium on Principles of programming languages (1993)

We show how a higher order logic, the calculus of constructions, can be used to give a simple, first principles treatment of record calculi, polymorphism, and subtyping. The development follows the constructive idiom of extracting implementations of equationally specified programs from proofs of their termination, with a logic for reasoning about programs, and a semantics that comes as a gratuity. In this framework, records are finitely specified functions where equality is decidable over the domain, with types that are a particular kind of logical assertion. By proving that a record specification satisfies its type, we can extract its implementation. While program extraction serves as a sort of compiler, proof normalization serves as an interpreter; the latter serves to ensure in some sense the coherence of the translation embedded in the former. This simple minded approach lets us show, for example, that many inference rules found in record and object calculi can be derived&mdash;they are just provable lemmas in higher order logic. We see explicitly how from subtyping proofs we can extract, using conventional methods, coercion functions between underlying representations of data types. By further exploiting the computational metaphor of higher order logic, we can realize an interpreter for recursively defined objects, as well as subtype and inheritance relations between them. Recursive types for objects are explained by primitive recursion in higher types. The approach also gives a computational understanding of F-bounded polymorphism.
Why and How of Requirements Tracing
Authors: Robert Watkins, Mark Neal
Venue: IEEE Software (1994)

While requirements traceability is explicitly required in US Department of Defense software contracts, it is often hard to sell in other situations. This article explains how Abbott Laboratories Diagnostics Division approaches traceability. To illustrate our program, we describe how we applied it to an R&D project to develop an embedded, real-time in vitro diagnostic instrument. The software is part of a system to test human body fluids for conditions such as cancer or hepatitis. We learned a great deal from this application and continue to experiment with and evolve the traceability-analysis process. In particular, we found that we must establish documentation rules and formats much earlier in the life cycle. Another lesson we learned is that traceability does cost. You need staff to support formal inspections or reviews. For most projects, you need some type of tool to assist in managing the trace matrices. We developed a relatively low-cost tool to handle our needs. Whatever the cost, it is important to include it as well as the costs for developing and maintaining procedures for documentation formats and generation, traceability analysis, and formal inspections. Our biggest lesson is that traceability is critical to project success. We believe it was one of the key factors in releasing our diagnostic instrument on time. Finally, we determined the conditions under which some type of traceability program is necessary.
An agent-oriented multiagent planning system
Authors: Kai-Hsiung Chang, William B. Day, Suebskul Phiphobmongkol
Venue: Proceedings of the 1993 ACM conference on Computer science (1993)

this paper describes a multiagent planning system, MuPAC, that formulates cooperative plans efficiently. It contains three features: meta-level planning, breakable and unbreakable action representations, and an integrated agent screening and assignment procedure. The meta-level planning transforms an original goal statement into a skeletal plan, which is easier to follow and helps reduce the chance of conflicts at low-level actions. The breakable/unbreakable action representation specifies specific agent-action requirements. It also specifies concurrency and cooperation possibilities among actions. It makes plan generation and agent assignment straight forward, thus reducing the reasoning time of finding parallelism and cooperation among agents. The integrated agent screening and assignment procedure formulates plans following the skeletal plan. The performance of MuPAC has been discussed along four aspects: planning efficiency, planning flexibility, agent cooperation, and plan quality. Results have shown that significant improvement has been achieved.
On lessons learned from A. A. Milne with contributions from Winnie the Pooh
Authors: Jean B. Gasen
Venue: ACM SIGCHI Bulletin (1993)

No matter how many courses, semesters and years pass by, I never seem to reach Christopher Robin's state of self-assurance. I am continually baffled by the challenge of determining "the best" method for organizing an HCI course and, like Eeyore, am never quite satisfied to remain with the status quo. So what's the big deal?