ppxscal/embedding_network huggingface dataset:
Diffusion Approximations for Some Multiclass Queueing Networks with FIFO Service Disciplines
Authors: Hong Chen, Hanqin Zhang
Venue: Mathematics of Operations Research (2000)

The diffusion approximation is proved for a class of multiclass queueing networks under FIFO service disciplines. In addition to the usual assumptions for a heavy traffic limit theorem, a key condition that characterizes this class is that aJ x J matrixG, known as the workload contents matrix, has a spectral radius less than unity, whereJ represents the number of service stations. The ( j,l)th component of matrixG can be interpreted as the long-run average amount of future work for stationj that is embodied in a unit of immediate work at stationl. This class includes, as a special case, the feedforward multiclass queueing network and the Rybko-Stolyar network under FIFO service discipline.A new approach is taken in establishing the diffusion limit theorem. The traditional approach is based on an oblique reflection mapping, but such a mapping is not well defined for the network under consideration. Our approach takes two steps: Arst establishing theC-tightness of the scaled queueing processes, and then completing the proof for the convergence of the scaled queueing processes by invoking the weak uniqueness for the limiting processes, which are semimartingale reflecting Brownian motions.
A efficient bit table technique for dynamic storage allocation of 2"-word blocks
Authors: Sadahiro Isoda, Eiichi Goto, Izumi Kimura
Venue: Communications of the ACM (1971)

An efficient bit table technique for dynamic storage allocation of 2n-word blocks, which requires a minimized amount of memory for bookkeeping purposes, is described. The technique has been tested in an implementation of the list processing language L6. A number of ideas incorporated in the processor are also described.
An Analysis of the Fundamental Structure of Complex-Valued Neurons
Authors: Tohru Nitta
Venue: Neural Processing Letters (2000)

This paper presents some results of an analysis on the decision boundaries of complex-valued neurons. The main results may be summarized as follows. (a) Weight parameters of a complex-valued neuron have a restriction which is concerned with two-dimensional motion. (b) The decision boundary of a complex-valued neuron consists of two hypersurfaces which intersect orthogonally, and divides a decision region into four equal sections.
Reduction of a band-symmetric generalized eigenvalue problem
Authors: C. R. Crawford
Venue: Communications of the ACM (1973)

An algorithm is described for reducing the generalized eigenvalue problem Ax = &lgr;Bx to an ordinary problem, in case A and B are symmetric band matrices with B positive definite. If n is the order of the matrix and m the bandwidth, the matrices A and B are partitioned into m-by-m blocks; and the algorithm is described in terms of these blocks. The algorithm reduces the generalized problem to an ordinary eigenvalue problem for a symmetric band matrix C whose bandwidth is the same as A and B. The algorithm is similar to those of Rutishauser and Schwartz for the reduction of symmetric matrices to band form. The calculation of C requires order n2m operation. The round-off error in the calculation of C is of the same order as the sum of the errors at each of the n/m steps of the algorithm, the latter errors being largely determined by the condition of B with respect to inversion.
Systems design education: a gaming approach
Authors: Norman R. Lyons
Venue: Communications of the ACM (1978)

One of the problems facing managers of computer installations is the problem of configuring the computer system to meet the demands made by the mix of jobs that the computer center must service, This paper presents a management game that allows the player to configure a computer system to meet a hypothetical job mix. The job mix is under the control of a game administrator and can be varied to simulate a variety of real-world situations (I/0 bound jobs, compute bound jobs, etc.). The player of the game receives a set of detailed reports on the cost of his choices and a simulated run of the center operating under his choices.
Deriving backtracking monad transformers
Authors: Ralf Hinze
Venue: Proceedings of the fifth ACM SIGPLAN international conference on Functional programming (2000)

In a paper about pretty printing J. Hughes introduced two fundamental techniques for deriving programs from their specification, where a specification consists of a signature and properties that the operations of the signature are required to satisfy. Briefly, the first technique, the term implementation, represents the operations by terms and works by defining a mapping from operations to observations --- this mapping can be seen as defining a simple interpreter. The second, the context-passing implementation, represents operations as functions from their calling context to observations. We apply both techniques to derive a backtracking monad transformer that adds backtracking to an arbitrary monad. In addition to the usual backtracking operations --- failure and nondeterministic choice --- the prolog cut and an operation for delimiting the effect of a cut are supported.
A linear lower bound on index size for text retrieval
Authors: Erik D. Demaine, Alejandro López-Ortiz
Venue: Proceedings of the twelfth annual ACM-SIAM symposium on Discrete algorithms (2001)

Most information-retrieval systems preprocess the data to produce an auxiliary index structure. Empirically, it has been observed that there is a tradeoff between query response time and the size of the index. When indexing a large corpus, such as the web, the size of the index is an important consideration. In this case it would be ideal to produce an index that is substantially smaller than the text. In this work we prove a linear lower bound on the size of any index that reports the location (if any) of a substring in the text in time proportional to the length of the pattern. In other words, an index supporting linear-time substring searches requires about as much space as the original text. Here &ldquo;time&rdquo; is measured in the number of bit probes to the text; an arbitrary amount of computation may be done on an arbitrary amount of the index. Our lower bound applies to inverted word indices as well.
Probabilistic agent programs
Authors: Jürgen Dix, Mirco Nanni, V. S. Subrahmanian
Venue: ACM Transactions on Computational Logic (TOCL) (2000)

Agents are small programs that autonomously take actions based on changes in their environment or &ldquo;state&rdquo;. Over the last few years, there has been an increasing number of efforts to build agents that can interact and/or collaborate with other agents. In one of these efforts Eiter et al. [1999] have shown how agents may be built on top of legacy code. However, their framework assumes that agent states are completely determined, and there is no uncertainty in an agent's state. Thus, their framework allows an agent developer to specify how his agents will react when the agent is 100% sure about what is true/false in the world state. In this paper, we propose the concept of a probabilistic agent program and show how, given an arbitrary program written in any imperative language, we may build a declarative &ldquo;probabilistic&rdquo; agent program on top of it which supports decision making in the presence of uncertainty. We provide two alternative semantics for probabilitic programs. We provide sound and complete algorithms to compute the semantics of positive agent programs.
Algorithms for computing the volume and other integral properties of solids. I. known methods and open issues
Authors: Yong Tsui Lee, Aristides A. G. Requicha
Venue: Communications of the ACM (1982)

The volume, moments of inertia, and similar properties of solids are defined by triple (volumetric) integrals over subsets of three-dimensional Euclidean space. The automatic computation of such integral properties for geometrically complex solids is important in CAD/CAM, robotics, and other fields and raises interesting mathematical and computational problems that have received little attention from numerical analysts and computer scientists. This paper summarizes the known methods for calculating integral properties of solids that may be geometrically complex and identifies some significant gaps in our current knowledge.
Intelligent object-based image retrieval suing cluster-driven personal preference learning
Authors: Kyong-Mi Lee, W. Nick Street
Venue: Proceedings of the 24th annual international ACM SIGIR conference on Research and development in information retrieval (2001)

This paper introduces a personalization method for image retrieval based on the learning of personal preferences. The proposed system indexes objects based on shape and groups them into a set of clusters, or prototypes. Our personalization method refines corresponding prototypes from objects provided by the user in the foreground, and simultaneously adapts the database index in the background.
Optimizing static calendar queues
Authors: K. Bruce Erickson, Richard E. Ladner, Anthony Lamarca
Venue: ACM Transactions on Modeling and Computer Simulation (TOMACS) (2000)

The calendar queue is an important implementation of a priority queue that is particularly useful in discrete event simulators. We investigate the performance of the static calendar queue that maintains N active events. The main contribution of this article is to prove that, under reasonable assumptions and with the proper parameter settings, the calendar queue data structure will have constant (independent of N) expected time per event processed. A simple formula is derived to approximate the expected time per event. The formula can be used to set the parameters of the calendar queue to achieve optimal or near optimal performance. In addition, a technique is given to calibrate a specific calendar queue implementation so that the formula can be applied in a practical setting.
Improving dynamic voltage scaling algorithms with PACE
Authors: Jacob R. Lorch, Alan Jay Smith
Venue: ACM SIGMETRICS Performance Evaluation Review (2001)

This paper addresses algorithms for dynamically varying (scaling) CPU speed and voltage in order to save energy. Such scaling is useful and effective when it is immaterial when a task completes, as long as it meets some deadline. We show how to modify any scaling algorithm to keep performance the same but minimize expected energy consumption. We refer to our approach as PACE (Processor Acceleration to Conserve Energy) since the resulting schedule increases speed as the task progresses. Since PACE depends on the probability distribution of the task's work requirement, we present methods for estimating this distribution and evaluate these methods on a variety of real workloads. We also show how to approximate the optimal schedule with one that changes speed a limited number of times. Using PACE causes very little additional overhead, and yields substantial reductions in CPU energy consumption. Simulations using real workloads show it reduces the CPU energy consumption of previously published algorithms by up to 49.5%, with an average of 20.6%, without any effect on performance.
A technique for isolating differences between files
Authors: Paul Heckel
Venue: Communications of the ACM (1978)

A simple algorithm is described for isolating the differences between two files. One application is the comparing of two versions of a source program or other file in order to display all differences. The algorithm isolates differences in a way that corresponds closely to our intuitive notion of difference, is easy to implement, and is computationally efficient, with time linear in the file length. For most applications the algorithm isolates differences similar to those isolated by the longest common subsequence. Another application of this algorithm merges files containing independently generated changes into a single file. The algorithm can also be used to generate efficient encodings of a file in the form of the differences between itself and a given &ldquo;datum&rdquo; file, permitting reconstruction of the original file from the diference and datum files.
A computer method for radiation treatment planning
Authors: William Siler, John S. Laughlin
Venue: Communications of the ACM (1962)

Automatic computation methods were first developed and applied to the problem of radiation therapy treatment planning by the Physics staff at Memorial Hospital and Sloan-Kettering Institute in 1954 and reported in 1955 [1]. The field of radiation from a single port was stored as a matrix in a library of punched cards, and a sorter and accounting machine were used to combine various fields for rotation, cycling and multi-port therapy. This system was in continuous routine use from then until 1961, when the equipment was replaced by a Bendix G15-D digital computer. Subsequent work by Sterling [2] followed essentially the same method of describing the radiation field as used by the Physics staff at Memorial Hospital [1], except that more powerful equipment has been used. An analytic expression for the dose distribution produced by rotation had been previously applied successfully in 1951 to treatment planning with high-energy X-rays [3].
A Low-Power CAM Design for LZ Data Compression
Authors: Kun-Jin Lin, Cheng-Wen Wu
Venue: IEEE Transactions on Computers (2000)

Low-power and high-performance data compressors play an increasingly important role in the portable mobile computing and wireless communication markets. Among lossless data compression algorithms for hardware implementation, LZ77 is one of the most widely used. For real-time communication, some hardware LZ compressors/decompressors have been proposed in the past. Content addressable memory (CAM) is widely considered as the most efficient architecture for pattern matching required by the LZ77 compression process. In this paper, we propose a low-power CAM-based LZ77 data compressor. By shutting down the power for unnecessary comparisons between the CAM words and the input symbol, the proposed CAM architecture consumes much lower power than the conventional ones without noticeable performance penalty. Moreover, using the proposed conditional comparison mechanism and the novel CAM cell with the NAND-type matching logic, on average we have close to two orders of improvement on power consumption, i.e., a reduction of more than 98 percent for 8-bit words. Speed is sacrificed if we use the NAND-type matching logic, but the NAND-type logic and the NOR-type logic can be combined to provide the best solution that balances power and delay. Our approach also can be applied to general-purpose CAMs which use the valid bits, so far as the proposed design techniques are adopted.
Roots of Independence Polynomials of Well Covered Graphs
Authors: J. I. Brown, K. Dilcher, R. J. Nowakowski
Venue: Journal of Algebraic Combinatorics: An International Journal (2000)

Let G be a well covered graph, that is, all maximal independent sets of G have the same cardinality, and let i_k denote the number of independent sets of cardinality k in G. We investigate the roots of the independence polynomial i(G, x) &equals; &sum; i_kx^k. In particular, we show that if G is a well covered graph with independence number &beta;, then all the roots of i(G, x) lie in in the disk &verbar;z&verbar; &le; &beta; (this is far from true if the condition of being well covered is omitted). Moreover, there is a family of well covered graphs (for each &beta;) for which the independence polynomials have a root arbitrarily close to &minus;&beta;.
The restriction language for computer grammars of natural language
Authors: Naomi Sager, Ralph Grishman
Venue: Communications of the ACM (1975)

Over the past few years, a number of systems for the computer analysis of natural language sentences have been based on augmented context-free grammars: a context-free grammar which defines a set of parse trees for a sentence, plus a group of restrictions to which a tree must conform in order to be a valid sentence analysis. As the coverage of the grammar is increased, an efficient representation becomes essential for further development. This paper presents a programming language designed specifically for the compact and perspicuous statement of restrictions of a natural language grammar. It is based on ten years' experience parsing text sentences with the comprehensive English grammar of the N.Y.U. Linguistic String Project, and embodies in its syntax and routines the relations which were found to be useful and adequate for computerized natural language analysis. The language is used in the current implementation of the Linguistic String Parser.
File organization: the consecutive retrieval property
Authors: Sakti P. Ghosh
Venue: Communications of the ACM (1972)

The consecutive retrieval property is an important relation between a query set and record set. Its existence enables the design of an information retrieval system with a minimal search time and no redundant storage. Some important theorems on the consecutive retrieval property are proved in this paper. Conditions under which the consecutive retrieval property exists and remain invariant have been established. An outline for designing an information retrieval system based on the consecutive retrieval property is also discussed.
The challenges of delivering content on the Internet
Authors: Tom Leighton
Venue: Proceedings of the twentieth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems (2001)

In this talk, we will give an overview of how content is distributed on the internet, with an emphasis on the approach being used by Akamai. We will describe some of the technical challenges involved in operating a network of thousands of content servers across multiple geographies on behalf of thousands of customers. The talk will be introductory in nature and should be accessible to a broad audience.
Hybrid system for multi-language and multi-environment generation of numerical codes
Authors: Joze Korelc
Venue: Proceedings of the 2001 international symposium on Symbolic and algebraic computation (2001)

The paper presents a hybrid system for automatic generation of numerical procedures for various finite element environments from the same symbolic description. The system consists of two major components. The Mathematica package AceGen is used for the automatic derivation of formulae needed in numerical procedures. An approach, implemented in AceGen, avoids the usual problem of uncontrollable growth of expressions by combining several techniques: symbolic and algebraic capabilities of Mathematica, automatic differentiation technique, automatic code generation, simultaneous optimization of expressions and theorem proving by a stochastic evaluation of the expressions. The Computational Templates package is a collection of prearranged modules for the creation of the finite element templates that enables the generation of multi-language and multi-environment finite element codes.
All-Pairs Almost Shortest Paths
Authors: Dorit Dor, Shay Halperin, Uri Zwick
Venue: SIAM Journal on Computing (2000)

Let G=(V,E) be an unweighted undirected graph on n vertices. A simple argument shows that computing all distances in G with an additive one-sided error of at most 1 is as hard as Boolean matrix multiplication. Building on recent work of Aingworth et al. [SIAM J. Comput., 28 (1999), pp. 1167--1181], we describe an $\Ot(\min\{n^{3/2}m^{1/2},n^{7/3}\})$-time algorithm APASP2 for computing all distances in G with an additive one-sided error of at most 2. Algorithm APASP2 is simple, easy to implement, and faster than the fastest known matrix-multiplication algorithm. Furthermore, for every even k>2, we describe an ${\tilde{O}}(\min\{n^{2-{2}/{(k+2)}}m^{{2}/{(k+2)}}, n^{2+{2}/{(3k-2)}}\})$-time algorithm APASPk for computing all distances in G with an additive one-sided error of at most k. We also give an ${\tilde{O}}(n^2)$-time algorithm ${\bf APASP}_\infty$ for producing stretch 3 estimated distances in an unweighted and undirected graph on n vertices. No constant stretch factor was previously achieved in ${\tilde{O}}(n^2)$ time.We say that a weighted graph F=(V,E') k-emulates an unweighted graph G=(V,E) if for every $u,v\in V$ we have $\delta_G(u,v)\le \delta_F(u,v)\le \delta_G(u,v)+k$. We show that every unweighted graph on n vertices has a 2-emulator with ${\tilde{O}}(n^{3/2})$ edges and a 4-emulator with ${\tilde{O}}(n^{4/3})$ edges. These results are asymptotically tight.Finally, we show that any weighted undirected graph on n vertices has a 3-spanner with ${\tilde{O}}(n^{3/2})$ edges and that such a 3-spanner can be built in ${\tilde{O}}(mn^{1/2})$ time. We also describe an ${\tilde{O}}(n(m^{2/3}+n))$-time algorithm for estimating all distances in a weighted undirected graph on n vertices with a stretch factor of at most 3.
Adaptive Control for Semilinear Stochastic Systems
Authors: T. E. Duncan, B. Maslowski, B. Pasik-Duncan
Venue: SIAM Journal on Control and Optimization (2000)

An adaptive, ergodic cost stochastic control problem for a partially known, semilinear, stochastic system in an infinite dimensional space is formulated and solved. The solutions of the Hamilton--Jacobi--Bellman equations for the discounted cost and the ergodic cost stochastic control problems require some special interpretations because they do not typically exist in the usual sense. The solutions of the parameter dependent ergodic Hamilton--Jacobi--Bellman equations are obtained from some corresponding discounted cost control problems as the discount rate tends to zero. The solutions of the ergodic Hamilton--Jacobi--Bellman equations are shown to depend continuously on the parameter. A certainty equivalence adaptive control is given that is based on the optimal controls from the solutions of the ergodic Hamilton--Jacobi--Bellman equations and a strongly consistent family of estimates of the unknown parameter. This adaptive control is shown to achieve the optimal ergodic cost for the known system.
Thoth, a portable real-time operating system
Authors: David R. Cheriton, Michael A. Malcolm, Lawrence S. Melen, Gary R. Sager
Venue: Communications of the ACM (1979)

Thoth is a real-time operating system which is designed to be portable over a large set of machines. It is currently running on two minicomputers with quite different architectures. Both the system and application programs which use it are written in a high-level language. Because the system is implemented by the same software on different hardware, it has the same interface to user programs. Hence, application programs which use Thoth are highly portable. Thoth encourages structuring programs as networks of communicating processes by providing efficient interprocess communication primitives.
The Design and Application of a Retargetable Peephole Optimizer
Authors: Jack W. Davidson, Christopher W. Fraser
Venue: ACM Transactions on Programming Languages and Systems (TOPLAS) (1980)

Peephole optimizers improve object code by replacing certain sequences of instructions with better sequences. This paper describes PO, a peephole optimizer that uses a symbolic machine description to simulate pairs of adjacent instructions, replacing them, where possible, with an equivalent single instruction. As a result of this organization, PO is machine independent and can be described formally and concisely: when PO is finished, no instruction, and no pair of adjacent instructions, can be replaced with a cheaper single instruction that has the same effect. This thoroughness allows PO to relieve code generators of much case analysis; for example, they might produce only load/add-register sequences and rely on PO to, where possible, discard them in favor or add-memory, add-immediate, or increment instructions. Experiments indicate that naive code generators can give good code if used with PO.