ppxscal/embedding_network huggingface dataset:
Competitive multicast routing
Authors: Baruch Awerbuch, Yossi Azar
Venue: Wireless Networks (1995)

In this paper, we introduce and solve the multicast routing problem for virtual circuit environment without making any assumptions about the communication patterns, or about the network topology. By multicast we refer to the case were one source transmits to several destination the same information. Also, we allow arbitrary interleaving of subscription patterns for different multicast groups, i.e. the destinations for each group arrive at an arbitrary order and may be interleaved with destinations of other groups. Our goal is to make route selection so as to minimize congestion of the bottleneck link. This is the first analytical treatment for this problem in its full generality. The main contribution of this paper is an online competitive routing strategy that has an O(\log n \log ) d competitive factor where n is the size of the network and d \leq n is the maximum size of a multicast group.
Recursive Filters for Optical Flow
Authors: David J. Fleet, Keith Langley
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1995)

Working toward efficient (real-time) implementations of optical flow methods, we have applied simple recursive filters to achieve temporal smoothing and differentiation of image intensity, and to compute 2d flow from component velocity constraints using spatiotemporal least-squares minimization. Accuracy in simulation is similar to that obtained in the study by Barron et al. [3], while requiring much less storage, less computation, and shorter delays.
Predicting RF coverage in large environments using ray-beam tracing and partitioning tree represented geometry
Authors: A. Rajkumar, B. F. Naylor, F. Feisullin, L. Rogers
Venue: Wireless Networks (1996)

We present a system for efficient prediction of RF power distribution in site specific environments using a variation of ray tracing, which we called ray-beam tracing. The simulation results were validated against measured data for a number of large environments with good statistical correlation between the two. We represent geometric environments in full 3D which facilitates rooftop deployment along with any other 3D locations. We use broadcast mode of propagation, whose cost increases more slowly with an increase in the number of receiving bins. The scheme works well both for indoor and outdoor environments. Simple ray tracing has a major disadvantage in that adjacent rays from a transmitter diverge greatly after large path lengths due to multiple reflections, such that arbitrarily large geometric entities could fall in between these rays. This results in a sampling error problem. The error increases arbitrarily as the incident angle approaches $90^\circ $. The problem is addressed by introducing the notion of beams while retaining the simplicity of rays for intersection calculations. A beam is adaptively split into child beams to limit the error. A major challenge for computational efficiency is to quickly determine the closest ray-surface intersection. We achieve this by using partitioning trees which allows representation of arbitrarily oriented polygonal environments. We also use partitioning trees for our full 3D interactive visualization along with interactive placement of transmitters, receiving bins, and querying of power.
Sharing memory robustly in message-passing systems
Authors: Hagit Attiya, Amotz Bar-Noy, Danny Dolev
Venue: Journal of the ACM (JACM) (1995)

Emulators that translate algorithms from the shared-memory model to two different message-passing models are presented. Both are achieved by implementing a wait-free, atomic, single-writer multi-reader register in unreliable, asynchronous networks. The two message-passing models considered are a complete network with processor failures and an arbitrary network with dynamic link failures.These results make it possible to view the shared-memory model as a higher-level language for designing algorithms in asynchronous distributed systems. Any wait-free algorithm based on atomic, single-writer multi-reader registers can be automatically emulated in message-passing systems, provided that at least a majority of the processors are not faulty and remain connected. The overhead introduced by these emulations is polynomial in the number of processors in the system.Immediate new results are obtained by applying the emulators to known shared-memory algorithms. These include, among others, protocols to solve the following problems in the message-passing model in the presence of processor or link failures: multi-writer multi-reader registers, concurrent time-stamp systems, l-exclusion, atomic snapshots, randomized consensus, and implementation of data structures.
Shape from Texture Using Local Spectral Moments
Authors: Boaz J. Super, Alan C. Bovik
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1995)

We present a non-feature-based solution to the problem of computing the shape of curved surfaces from texture information. First, the use of local spatial-frequency spectra and their moments to describe texture is discussed and motivated. A new, more accurate method for measuring the local spatial-frequency moments of an image texture using Gabor elementary functions and their derivatives is presented. Also described is a technique for separating shading from texture information, which makes the shape-from-texture algorithm robust to the shading effects found in real imagery. Second, a detailed model for the projection of local spectra and spectral moments of any surface reflectance patterns (not just textures) is developed. Third, the conditions under which the projection model can be solved for the orientation of the surface at each point are explored. Unlike earlier non-feature-based, curved surface shape-from-texture approaches, the assumption that the surface texture is isotropic is not required; surface texture homogeneity can be assumed instead. The algorithm¿s ability to operate on anisotropic and non-deterministic textures, and on both smooth- and rough-textured surfaces, is demonstrated.
Rule-based versus structure-based models for explaining and generating expert behavior
Authors: Vasant Dhar, Harry E. Pople
Venue: Communications of the ACM (1987)

Flexible representations are required in order to understand and generate expert behavior. Although production rules with quantifiers can encode experiential knowledge, they often have assumptions implicit in them, making them brittle in problem scenarios where these assumptions do not hold. Qualitative models achieve flexibility by representing the domain entities and their interrelationships explicitly. However, in problem domains where assumptions underlying such models change periodically, it is necessary to be able to synthesize and maintain qualitative models in response to the changing assumptions. In this paper we argue for a representation that contains partial model components that are synthesized into qualitative models containing entities and relationships relevant to the domain. The model components can be replaced and rearranged in response to changes in the task environment. We have found this "model constructor" to be useful in synthesizing models that explain and generate expert behavior, and have explored its ability to support decision making in the problem domain of business resource planning, where reasoning is based on models that evolve in response to changing external conditions or internal policies.
A new algorithm for the design of stable higher order single loop sigma delta analog-to-digital converters
Authors: S. R. Kadivar, D. Schmitt-Landsiedel, H. Klar
Venue: Proceedings of the 1995 IEEE/ACM international conference on Computer-aided design (1995)

Abstract: This paper presents a new algorithm to attain optimized network scaling in single loop, 1 bit Sigma Delta Analog 1d Digital Converters (SD ADC) of order three or more. The algorithm is based on a novel mathematical description of stability and performance criteria of the SD ADC and on the application of nonlinear interactive optimization techniques. The feasibility of the new algorithm has been confirmed in practical implementations. The method brings new insight on the correlation between system stability, performance, system order and the choice of the network scaling. Our method is extendible to cascaded SD as well as SD based on filter topologies.
Reforming telecommunications law
Authors: Fred W. Weingarten
Venue: Communications of the ACM (1995)

The heroic effort to rewrite the nation's 60-year-old telecommunications law failed in September when Sen. Fritz Hollings (D-S.C.), chair of the Senate Commerce Committee, gave up trying to bring his vehicle for reform, Bill S-1822, to the floor for a vote before adjournment.
A linear-time algorithm for computing the memory access sequence in data-parallel programs
Authors: Ken Kennedy, Nenad Nedeljkovic, Ajay Sethi
Venue: Proceedings of the fifth ACM SIGPLAN symposium on Principles and practice of parallel programming (1995)

Data-parallel languages, such as High Performance Fortran, are widely regarded as a promising means for writing portable programs for distributed-memory machines. Novel features of these languages call for the development of new techniques in both compilers and run-time systems. In this paper, we present an improved algorithm for finding the local memory access sequence in computations involving regular sections of arrays with cyclic(k) distributions. After establishing the fact that regular section indices correspond to elements of an integer lattice, we show how to find a lattice basis that allows for simple and fast enumeration of memory accesses. The complexity of our algorithm is shown to be lower than that of the previous solution for the same problem. In addition, the experimental results demonstrate the efficiency of our method in practice.
System partitioning to maximize sleep time
Authors: Amir H. Farrahi, Majid Sarrafzadeh
Venue: Proceedings of the 1995 IEEE/ACM international conference on Computer-aided design (1995)

Abstract: Partitioning of a system to maximize exploitable sleep time for low-power synthesis is discussed. The motivation is to deactivate the memory refresh circuitry, apply power down or disable the clock signals during the inactive periods of operation of circuit elements, and thus minimize the power consumption. Since it is impractical to have a separate set of control signals for each circuit element (otherwise, the control itself would consume a lot of power), it is advisable to partition a circuit based on the activity patterns of its elements so that the partitions can be switched into sleep mode for long periods of time. In this paper, we formulate this partitioning problem and show that it is NP-hard. We present Geo-Part, a geometric partitioning heuristic for this problem. An efficient implementation of Geo-Part using segment tree data structure is discussed. Experimental results are encouraging.
The complexity gap
Authors: L. B. S. Raccoon
Venue: ACM SIGSOFT Software Engineering Notes (1995)

The Complexity Gap defines a new way to think about software development. We have all heard that developers need to be more productive and to work harder. But what does this mean exactly? The Complexity Gap defines a structure in which to explore concepts of process and productivity and to show how these concepts relate to conventional software development issues of tools and training.Software development is complex. This paper expands on the principles of the Chaos model that suggest that the top-level user requirements and bottom-level hacking are connected through many intermediate levels, and that every level of software development affects quality and productivity to the same degree. In The Chaos Model and the Chaos Life Cycle, I make these points.To clarify the possibilities and limitations of software development, I compare software development to assembly-line work. In the software engineering community, we compare software development to assembly lines for a variety of reasons. Some managers want to acquire the same sense of control over software development as factory managers have over assembly lines. Other managers want to apply assembly-line techniques, such as Statistical Quality Control, to software development. I use both the definition of the Complexity Gap and the assembly-line analogy to suggest ways to improve the software development process.
Symbolic array dataflow analysis for array privatization and program parallelization
Authors: Junjie Gu, Zhiyuan Li, Gyungho Lee
Venue: Proceedings of the 1995 ACM/IEEE conference on Supercomputing (CDROM) (1995)

Array dataflow information plays an important role for successful automatic parallelization of Fortran programs. This paper proposes a powerful symbolic array dataflow analysis to support array privatization and loop parallelization for programs with arbitrary control flow graphs and acyclic call graphs. Our scheme summarizes array access information using guarded array regions and propagates such regions over a Hierarchical Supergraph (HSG). The use of guards allows us to use the information in IF conditions to sharpen the array dataflow analysis and thereby to handle difficult cases which elude other existing techniques. The guarded array regions retain the simplicity of set operations for regular array regions in common cases, and they enhance regular array regions in complicated cases by using guards to handle complex symbolic expressions and array shapes. Scalar values that appear in array subscripts and loop limits are substituted on the fly during the array information propagation, which disambiguates the symbolic values precisely for set operations. We present efficient algorithms that implement our scheme. Initial experiments of applying our analysis to Perfect Benchmarks show promising results of improved array privatization.
Applying Bayesian networks to information retrieval
Authors: Robert Fung
Venue: Communications of the ACM (1995)

Information retrieval (IR) is the identification of documents or other units of information in a collection that are relevant to a particular information need. An information need is a set of questions to which someone would like to find an answer. Here are some examples of IR tasks: finding articles in the New York Times that discuss the Iran-Contra affair; searching the recent postings in a Usenet newsgroup for references to a particular model of personal computer; finding the entries referring to butterflies in an online CD-ROM encyclopedia.
Heavy Traffic Analysis of a Controlled Multiclass Queueing Network via Weak Convergence Methods
Authors: Harold J. Kushner, L. Felipe Martins
Venue: SIAM Journal on Control and Optimization (1996)

The workload formulation due to Harrison and coworkers of multiclass queueing networks has been fundamental to its analysis. Until recently, there was no actual theory which started with the physical queue and showed that under heavy traffic conditions, the optimal costs could be approximated by those for an optimization problem using the ``limit'' workload equations. Recently, this was done via viscosity solution methods by Martins, Shreve, and Soner for one important class. For this same class of problems (and including the cases not treated there), we use weak convergence methods to show that the sequence of optimal costs for the original network converges to the optimal cost for the workload limit problem. The proof is simpler and allows weaker (and non-Markovian) conditions. It uses current techniques in weak convergence analysis. It seems to be the first analysis of such multiclass ``workload'' problems by weak convergence methods. The general structure of the development seems applicable to the analysis of more complex systems.
Efficient orthonormality testing for synthesis with pass-transistor selectors
Authors: Michel Berkelaar, Lukas P. P. P. van Ginneken
Venue: Proceedings of the 1995 IEEE/ACM international conference on Computer-aided design (1995)

This paper presents the mapping problem for pass transistor selector mapping, which has not been addressed before. Pass transistor synthesis is potentially important for semi- or full-custom design techniques, which are increasingly attracting attention. Pass transistors have the advantage that fewer transistors are needed, and that circuits with high fanin and small delay can be constructed. Technology mapping approaches in the existing literature cannot handle these selectors, due to the restriction of 1-hot encoding of the control signals. We present a new algorithm to address this problem, which is based on the novel idea of a general Boolean Oracle. Our oracle is based on ATPG techniques, and compared to BDDs, the oracle has the advantage that failure to complete only affects optimization locally, and does not hinder optimization elsewhere in the logic. A limitation of BDDs is that it is difficult to complete the algorithm if a BDD grows too large. The experimental results show up to 82% improvement in transistor count for the MCNC combinatorial multi-level examples.
Algorithm 742: L2CXFT: a Fortran subroutine for least-squares data fitting with nonnegative second divided differences
Authors: I. C. Demetriou
Venue: ACM Transactions on Mathematical Software (TOMS) (1995)

A Fortran subroutine applies the method of Demetriou and Powell [1991] to restore convexity in n measurements of a convex function contaminated by random errors. The method minimizes the sum of the squares of the errors, subject to nonnegativity of second divided differences, in two phases. First, an approximation close to the optimum is derived in O(n) operations. Then, this approximation is used as the starting point of a dual-feasible quadratic programming algorithm that completes the calculation of the optimum. The constraints allow B-splines to be used, which reduce the problem to an equivalent one with fewer variables where the knots of the splines are determined automatically from the data points due to the constraint equations. The subroutine benefits from this reduction, since common submatrices that occur during the calculation are updated suitably. Iterative refinement improves the accuracy of some calculations when round-off errors accumulate. The subroutine has been applied to a variety of data having substantial differences and has performed fast and stably even for small data spacing, large n, and single-precision arithmetic. Driver programs and examples with output are provided to demonstrate the use of the subroutine.
A framework for supporting data integration using the materialized and virtual approaches
Authors: Richard Hull, Gang Zhou
Venue: ACM SIGMOD Record (1996)

This paper presents a framework for data integration currently under development in the Squirrel project. The framework is based on a special class of mediators, called Squirrel integration mediators. These mediators can support the traditional virtual and materialized approaches, and also hybrids of them.In the Squirrel mediators, a relation in the integrated view can be supported as (a) fully materialized, (b) fully virtual, or (c) partially materialized (i.e., with some attributes materialized and other attributes virtual). In general, (partially) materialized relations of the integrated view are maintained by incremental updates from the source databases. Squirrel mediators provide two approaches for doing this: (1) materialize all needed auxiliary data, so that data sources do not have to be queried when processing the incremental updates; or (2) leave some or all of the auxiliary data virtual, and query selected source databases when processing incremental updates.The paper presents formal notions of consistency and "freshness" for integrated views defined over multiple autonomous source databases. It is shown that Squirrel mediators satisfy these properties.
The ACM electronic publishing plan
Authors: Peter J. Denning, Bernard Rous
Venue: Communications of the ACM (1995)

For the past three years, the ACM Publications Board has been developing its vision for the future of publication in the electronic age and a program to achieve it. I am pleased to present that plan here. We envisage a diminishing role for print journals and exciting new programs around an ACM digital library. The plan raises important policy questions regarding the treatment of copyright. Our interim answers to these policy questions are discussed in two additional documents&mdash;the ACM Interim Copyright Policies and the ACM Author's Guide to the Interim Copyright Policies. Our overall intention is to move aggressively into electronic publishing and to preserve the traditional openness of ACM publications in the new media. Authors and readers should find these policies at least as hospitable as the traditional ones.
A Polylogarithmic Bound for an Iterative Substructuring Method for Spectral Elements in Three Dimensions
Authors: Luca F. Pavarino, Olof B. Widlund
Venue: SIAM Journal on Numerical Analysis (1996)

Iterative substructuring methods form an important family of domain decomposition algorithms for elliptic finite element problems. A $p$-version finite element method based on continuous, piecewise $Q_p$ functions is considered for second-order elliptic problems in three dimensions; this special method can also be viewed as a conforming spectral element method. An iterative method is designed for which the condition number of the relevant operator grows only in proportion to $(1+\log p)^2 .$ This bound is independent of jumps in the coefficient of the elliptic problem across the interfaces between the subregions. Numerical results are also reported which support the theory.
A hybrid analytical/simulation modeling approach for planning mass tactical airborne operations
Authors: David D. Briggs, Mansooreh Mollaghasemi, José A. Sepúlveda
Venue: Proceedings of the 27th conference on Winter simulation (1995)

A hybrid analytical/simulation model is developed to plan for mass tactical airborne operations. This automated tool enables the user to properly load aircraft according to the mission and user specifications, so that the minimum amount of time is required to seize all assigned objectives. The first portion is a mathematical model that once solved provides the optimal manifest under "perfect conditions". This analytical model is represented by a transportation network, and optimized using a transportation algorithm. The results of this solution are input to an integrated simulation model that introduces the inherent variability. The simulation returns the expected, best, and worst arrival times, and the build up of power over time. This hybrid approach allows a very large problem to be solved efficiently with a great deal of time savings.
Comparison of Raw and Internet protocols in a HIPPI/ATM/SONET based gigabit network
Authors: Raj K. Singh, Stephen G. Tell, Shaun J. Bharrat
Venue: ACM SIGCOMM Computer Communication Review (1996)

We compare implementation of Raw and Internet protocols (TCP, UDP) on a programmable HIPPI host-interface called the Network Interface Unit. The network interface unit connects Pixel-Planes 5, a message-based graphics multicomputer, to a wide area gigabit network called VISTAnet. The BISDN network consists of a SONET cross-connect switch and an ATM switch. We discuss the tradeoffs between protocols for our target application and present a comparison of end-to-end throughput based on empirical measurements.