ppxscal/embedding_network huggingface dataset:
A multilevel algorithm for partitioning graphs
Authors: Bruce Hendrickson, Robert Leland
Venue: Proceedings of the 1995 ACM/IEEE conference on Supercomputing (CDROM) (1995)

The graph partitioning problem is that of dividing the vertices of a graph into sets of specified sizes such that few edges cross between sets. This NP-complete problem arises in many important scientific and engineering problems. Prominent examples include the decomposition of data structures for parallel computation, the placement of circuit elements and the ordering of sparse matrix computations. We present a multilevel algorithm for graph partitioning in which the graph is approximated by a sequence of increasingly smaller graphs. The smallest graph is then partitioned using a spectral method, and this partition is propagated back through the hierarchy of graphs. A variant of the Kernighan-Lin algorithm is applied periodically to refine the partition. The entire algorithm can be implemented to execute in time proportional to the size of the original graph. Experiments indicate that, relative to other advanced methods, the multilevel algorithm produces high quality partitions at low cost.
Service and network management in the OAMS open service architecture
Authors: Simon Znaty
Venue: ACM SIGCOMM Computer Communication Review (1996)

New open service architectures are now emerging to ease service construction, management, testing, deployment, and operation, and to hide from the service designer the heterogeneity of the underlying technologies and the complexities introduced by distribution. These architectures should provide all the functionalities for call and connection management, and support management functional areas. To reach these objectives, information models must be defined which provide service and network representations by data. This paper presents the specification, design and implementation of the management architecture of OAMS which is an open service architecture. The proposed architecture is deployed over the distributed processing environment DCE2. It exhibits service, network and element management views by means of information models, in order to manage the end-to-end connectivity requested by telecommunication services.
Parallel and distributed simulation
Authors: Richard M. Fujimoto
Venue: Proceedings of the 27th conference on Winter simulation (1995)

Research and development efforts in the parallel and distributed simulation field over the last 15 years has progressed, largely independently, in two separate camps: the largely academic high performance parallel and distributed (discrete event) simulation (PADS) community, and the DoD-centered distributed interactive simulation (DIS) community. This tutorial gives an overview and comparison of work in these two areas, emphasizing issues related to distributed execution where these fields have the most overlap. Differences in the fundamental assumptions routinely used within each community are contrasted, followed by overviews of work in each community.
A comparison of three user interfaces to relational microcomputer data bases
Authors: Carl Medsker, Margaret Christensen, Il-Yeol Song
Venue: ACM SIGMOD Record (1995)

PAYOFF IDEA. Different styles of user interfaces can dramatically affect data base capabilities. In an environment comprising many different data bases, the goal is to select one data base management system (DBMS) that provides the best selection of design tools, minimizes development times, and enforces relational rules. This article presents a case study performed at the Hospital of the University of Pennsylvania, in which a test data base was developed for implementation with three DBMSs, each with a distinctly different user and programmer interface.
The anomaly of other-directedness: when normally ethical I.S. personnel are unethical
Authors: Susan J. Harrington
Venue: ACM SIGCPR Computer Personnel (1995)

Despite the existence of laws and much publicity surrounding illegal software copying, it is widely believed that software copying is commonplace. Yet reasons why such illegal behavior continues to occur are lacking. This study used a model of ethical decision making as a guide for research and found the individual factor of other-directedness helped explain IS personnel's intentions toward illegal software copying. No such individual factor was related to judgments concerning right and wrong. These findings suggest that highly other-directed IS personnel may behave against their better judgment, especially in cases where they perceive unethical behavior is commonplace. Implications for management and ethics education are discussed.
ALECSYS and the AutonoMouse: Learning to Control a Real Robot by Distributed Classifier Systems
Authors: Marco Dorigo
Venue: Machine Learning (1995)

In this article we investigate the feasibility of using learning classifier systems as a tool for building adaptive control systems for real robots. Their use on real robots imposes efficiency constraints which are addressed by three main tools: parallelism, distributed architecture, and training. Parallelism is useful to speed up computation and to increase the flexibility of the learning system design. Distributed architecture helps in making it possible to decompose the overall task into a set of simpler learning tasks. Finally, training provides guidance to the system while learning, shortening the number of cycles required to learn. These tools and the issues they raise are first studied in simulation, and then the experience gained with simulations is used to implement the learning system on the real robot. Results have shown that with this approach it is possible to let the AutonoMouse, a small real robot, learn to approach a light source under a number of different noise and lesion conditions.
Dynamic cell structure learns perfectly topology preserving map
Authors: Jörg Bruske, Gerald Sommer
Venue: Neural Computation (1995)

Dynamic cell structures (DCS) represent a family of artificial neural architectures suited both for unsupervised and supervised learning. They belong to the recently (Martinetz 1994) introduced class of topology representing networks (TRN) that build perfectly topology preserving feature maps. DCS employ a modified Kohonen learning rule in conjunction with competitive Hebbian learning. The Kohonen type learning rule serves to adjust the synaptic weight vectors while Hebbian learning establishes a dynamic lateral connection structure between the units reflecting the topology of the feature manifold. In case of supervised learning, i.e., function approximation, each neural unit implements a radial basis function, and an additional layer of linear output units adjusts according to a delta-rule. DCS is the first RBF-based approximation scheme attempting to concurrently learn and utilize a perfectly topology preserving map for improved performance. Simulations on a selection of CMU-Benchmarks indicate that the DCS idea applied to the growing cell structure algorithm (Fritzke 1993c) leads to an efficient and elegant algorithm that can beat conventional models on similar tasks.
Balancing processor loads and exploiting data locality in N-body simulations
Authors: Ioana Banicescu, Susan Flynn Hummel
Venue: Proceedings of the 1995 ACM/IEEE conference on Supercomputing (CDROM) (1995)

Although N-body simulation algorithms are amenable to parallelization, performance gains from execution on parallel machines are difficult to obtain due to load imbalances caused by irregular distributions of bodies. In general, there is a tension between balancing processor loads and maintaining locality, as the dynamic re-assignment of work necessitates access to remote data. Fractiling is a dynamic scheduling scheme that simultaneously balances processor loads and maintains locality by exploiting the self-similarity properties of fractals. Fractiling is based on a probabilistic analysis, and thus, accommodates load imbalances caused by predictable phenomena, such as irregular data, and unpredictable phenomena, such as data-access latencies. In experiments on a KSR1, performance of N-body simulation codes were improved by as much as 53% by fractiling. Performance improvements were obtained on uniform and nonuniform distributions of bodies, underscoring the need for a scheduling scheme that accommodates system induced variance. As the fractiling scheme is orthogonal to the N-body algorithm, we could use simple codes that discretize space into equal-size subrectangles (2-d) or subcubes (3-d) as the base algorithms.
The Stanford Digital Library Project
Authors: CORPORATE The Stanford Digital Libraries Group
Venue: Communications of the ACM (1995)

The Stanford Integrated Digital Library Project will develop enabling technologies for an integrated &ldquo;virtual&rdquo; library to provide an array of new services and uniform access to networked information collections. The Integrated Digital Library will create a shared environment linking everything from personal information collections, to collections of conventional libraries, to large data collections shared by scientists.
Built-In Test for Circuits with Scan Based on Reseeding of Multiple-Polynomial Linear Feedback Shift Registers
Authors: Sybille Hellebrand, Janusz Rajski, Steffen Tarnick, Srikanth Venkataraman, Bernard Courtois
Venue: IEEE Transactions on Computers (1995)

In this paper, we propose a new scheme for Built-In Test (BIT) that uses Multiple-polynomial Linear Feedback Shift Registers (MP-LFSR's). The same MP-LFSR that generates random patterns to cover easy to test faults is loaded with seeds to generate deterministic vectors for difficult to test faults. The seeds are obtained by solving systems of linear equations involving the seed variables for the positions where the test cubes have specified values. We demonstrate that MP-LFSR's produce sequences with significantly reduced probability of linear dependence compared to single polynomial LFSR's. We present a general method to determine the probability of encoding as a function of the number of specified bits in the test cube, the length of the LFSR and the number of polynomials. Theoretical analysis and experiments show that the probability of encoding a test cube with $s$ specified bits in an $s$-stage LFSR with 16 polynomials is 1¿10$^{-6}.$ We then present the new BIT scheme that allows for an efficient encoding of the entire test set. Here the seeds are grouped according to the polynomial they use and an implicit polynomial identification reduces the number of extra bits per seed to one bit. The paper also shows methods of processing the entire test set consisting of test cubes with varied number of specified bits. Experimental results show the tradeoffs between test data storage and test application time while maintaining complete fault coverage.Index Terms¿Built-In Test, hardware test pattern generators, input test data compression and decompression, multiple-polynomial LFSR, reseeding, scan design.
A new approach to the minimum cut problem
Authors: David R. Karger, Clifford Stein
Venue: Journal of the ACM (JACM) (1996)

This paper present a new approach to finding minimum cuts in undirected graphs. The fundamental principle is simple: the edges in a graph's minimum cut form an extremely small fraction of the graph's edges. Using this idea, we give a randomized, strongly polynomial algorithm that finds the minimum cut in an arbitrarily weighted undirected graph with high probability. The algorithm runs in O(n2log3n) time, a significant improvement over the previous O&tilde;(mn) time bounds based on maximum flows. It is simple and intuitive and uses no complex data structures. Our algorithm can be parallelized to run in RNC with n2 processors; this gives the first proof that the minimum cut problem can be solved in RNC. The algorithm does more than find a single minimum cut; it finds all of them.With minor modifications, our algorithm solves two other problems of interest. Our algorithm finds all cuts with value within a multiplicative factor of &agr; of the minimum cut's in expected O&tilde;(n2&agr;) time, or in RNC with n2&agr; processors. The problem of finding a minimum multiway cut of graph into r pieces is solved in expected O&tilde;(n2(r-1)) time, or in RNC with n2(r-1) processors. The &ldquo;trace&rdquo; of the algorithm's execution on these two problems forms a new compact data structure for representing all small cuts and all multiway cuts in a graph. This data structure can be efficiently transformed into the more standard cactus representing for minimum cuts.
Predicting document access in large multimedia repositories
Authors: Margaret M. Recker, James E. Pitkow
Venue: ACM Transactions on Computer-Human Interaction (TOCHI) (1996)

Network-accessible multimedia databases, repositories, and libraries are proliferating at a rapid rate. A crucial problem for these repositories remains timely and appropriate document access. In this article, we borrow a model from psychological research on human memory, which has long studied retrieval of memory items based on frequency and recency rates of past item occurrences. Specifically, the model uses frequency and recency rates of prior document accesses to predict future document requests. The model is illustrated by analyzing the log file of document accesses to the Georgia Institute of Technology World Wide Web (WWW) repository, a large multimedia respository exhibiting high access rates. Results show that the model predicts document access rates with a reliable degree of accuracy. We describe extensions to the basic approach that combine the recency and frequency analyses and which incorporate respository structure and document type. These results have implications for the formulation of descriptive user models of information access in large repositories. In addition, we sketch applications in the areas of design of information systems and interfaces and their document-caching algorithms.
Matrix Powers in Finite Precision Arithmetic
Authors: Nicholas J. Higham, Philip A. Knight
Venue: SIAM Journal on Matrix Analysis and Applications (1995)

If $A$ is a square matrix with spectral radius less than 1 then $A^k \to 0$ as $k \to \infty$, but the powers computed in finite precision arithmetic may or may not converge. We derive a sufficient condition for $fl(A^k) \to 0$ as $k\to\infty$ and a bound on $\norm{fl(A^k)}$, both expressed in terms of the Jordan canonical form of $A$. Examples show that the results can be sharp. We show that the sufficient condition can be rephrased in terms of a pseudospectrum of $A$ when $A$ is diagonalizable, under certain assumptions. Our analysis leads to the rule of thumb that convergence or divergence of the computed powers of $A$ can be expected according as the spectral radius computed by any backward stable algorithm is less than or greater than 1.
Rule languages and internal algebras for rule-based optimizers
Authors: Mitch Cherniack, Stanley B. Zdonik
Venue: ACM SIGMOD Record (1996)

Rule-based optimizers and optimizer generators use rules to specify query transformations. Rules act directly on query representations, which typically are based on query algebras. But most algebras complicate rule formulation, and rules over these algebras must often resort to calling to externally defined bodies of code. Code makes rules difficult to formulate, prove correct and reason about, and therefore compromises the effectiveness of rule-based systems.In this paper we present KOLA: a combinator-based algebra designed to simplify rule formulation. KOLA is not a user language, and KOLA's variable-free queries are difficult for humans to read. But KOLA is an effective internal algebra because its combinator-style makes queries manipulable and structurally revealing. As a result, rules over KOLA queries are easily expressed without the need for supplemental code. We illustrate this point, first by showing some transformations that despite their simplicity, require head and body routines when expressed over algebras that include variables. We show that these transformations are expressible without supplemental routines in KOLA. We then show complex transformations of a class of nested queries expressed over KOLA. Nested query optimization, while having been studied before, have seriously challenged the rule-based paradigm.
Combinatorial Algorithm for a Lower Bound on Frame Rigidity
Authors: D. S. Franzblau
Venue: SIAM Journal on Discrete Mathematics (1995)

A classic problem is that of computing the rigidity of a network of rigid bars or, more formally, computing the degrees of freedom of a frame, a graph with a generic straightline embedding in Euclidean space. More recently, in trying to explain the effect of the internal structure of glassy materials on their rigidity, researchers have investigated the relationship between the structure of network models and the number of degrees of freedom. It would thus be valuable to have an efficient, purely combinatorial algorithm to compute the degrees of freedom of an arbitrary frame. For frames in two dimensions, there are several such algorithms, all based on a theorem of Laman. However, despite considerable effort, no one has yet found such an algorithm for frames in three or more dimensions. Here, a new combinatorial approach, similar to ear decomposition, is introduced and shown to give a practical algorithm for computing a nontrivial lower bound on the number of degrees of freedom in three dimensions. Results of computational studies on an important class of network models of glasses are given, suggesting that the resulting bound is close to the exact answer in the cases of interest. The algorithm has been implemented in $O(n)$ space and $O(n^{2})$ time for bounded-degree networks with $n$ vertices and has already provided new results of interest on these networks.
AVCS: the APL version control system
Authors: Nikolai I. Puntikov, Maxim A. Volodin, Alexei A. Kolesnikov
Venue: ACM SIGAPL APL Quote Quad (1995)

This paper described AVCS, which is an APL-oriented version control system devised as a tool to track the history of software projects and to control concurrent access to project components. The basics of version control systems are explained, and specific aspects of applying a version control system methodology to project development in APL environments are considered. Particular attention is given to features which differentiate the approach accepted in AVCS from that of available version control and project management systems. Specification of AVCS's data maintenance, programming and user interface is presented to the extent required in order to explain how the system works. In conclusion, the possible application of AVCS to solving problems of porting APL projects across different environments is outlined.
Message-Optimal Protocols for Fault-Tolerant Broadcasts/Multicasts in Distributed Systems with Crash Failures
Authors: Hong-Yi Tzeng, Kai-Yeung Siu
Venue: IEEE Transactions on Computers (1995)

An essential feature in any fault-tolerant design of distributed systems is a mechanism by which a process can reliably broadcast information to other processes in the presence of failures. This paper studies the message complexity of fault-tolerant broadcast protocols in weakly synchronous and totally asynchronous distributed systems with point-to-point communication links, where the system failures are caused by the processes but the communication links are completely reliable. We focus on the number of messages required of any fault-tolerant protocol in failure-free executions. Our motivation is that one should incur the cost of handling failures only when they actually occur. We present protocols that, in an $n$-process system subject to at most $t$ crash failures where $1 \leq t\,{\char'074}\,(n - 1)$, guarantee the delivery of a message from any process to other nonfaulty processes. In the absence of crash failures, our protocols require $(n + t - 1)$ messages in the weakly synchronous model and $(t + 1)(n - 1 - (t/2))$ messages in the totally asynchronous model. Moreover, we show that in both cases our protocols are optimal with respect to message complexity. The new insights provided in our lower bound proofs also yield graph-theoretic characterizations of all message-optimal reliable broadcast protocols in failure-free executions. Both the upper and lower bound results on broadcast protocols can be generalized to multicast protocols, where a process only needs to deliver a message to a subset of processes in the system.Index Terms¿ Reliable broadcasts/multicasts, distributed computing, network protocols, fault tolerance, message complexity.
A Bayesian Segmentation Methodology for Parametric Image Models
Authors: Steven M. LaValle, Seth A. Hutchinson
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1995)

Region-based image segmentation methods require some criterion for determining when to merge regions. This paper presents a novel approach by introducing a Bayesian probability of homogeneity in a general statistical context. Our approach does not require parameter estimation and is therefore particularly beneficial for cases in which estimation-based methods are most prone to error: when little information is contained in some of the regions and, therefore, parameter estimates are unreliable. We apply this formulation to three distinct parametric model families that have been used in past segmentation schemes: implicit polynomial surfaces, parametric polynomial surfaces, and Gaussian Markov random fields. We present results on a variety of real range and intensity images.
FastMap: a fast algorithm for indexing, data-mining and visualization of traditional and multimedia datasets
Authors: Christos Faloutsos, King-Ip Lin
Venue: Proceedings of the 1995 ACM SIGMOD international conference on Management of data (1995)

A very promising idea for fast searching in traditional and multimedia databases is to map objects into points in k-d space, using k feature-extraction functions, provided by a domain expert [25]. Thus, we can subsequently use highly fine-tuned spatial access methods (SAMs), to answer several types of queries, including the 'Query By Example' type (which translates to a range query); the 'all pairs' query (which translates to a spatial join [8]); the nearest-neighbor or best-match query, etc.However, designing feature extraction functions can be hard. It is relatively easier for a domain expert to assess the similarity/distance of two objects. Given only the distance information though, it is not obvious how to map objects into points.This is exactly the topic of this paper. We describe a fast algorithm to map objects into points in some k-dimensional space (k is user-defined), such that the dis-similarities are preserved. There are two benefits from this mapping: (a) efficient retrieval, in conjunction with a SAM, as discussed before and (b) visualization and data-mining: the objects can now be plotted as points in 2-d or 3-d space, revealing potential clusters, correlations among attributes and other regularities that data-mining is looking for.We introduce an older method from pattern recognition, namely, Multi-Dimensional Scaling (MDS) [51]; although unsuitable for indexing, we use it as yardstick for our method. Then, we propose a much faster algorithm to solve the problem in hand, while in addition it allows for indexing. Experiments on real and synthetic data indeed show that the proposed algorithm is significantly faster than MDS, (being linear, as opposed to quadratic, on the database size N), while it manages to preserve distances and the overall structure of the data-set.
General Optimality Conditions for Constrained Convex Control Problems
Authors: Maitine Bergounioux, Dan Tiba
Venue: SIAM Journal on Control and Optimization (1996)

In this paper we investigate some optimal convex control problems, with mixed constraints on the state and the control. We give a general condition which allows us to set optimality conditions for nonqualified problems (in the Slater sense). Then we give some applications and examples involving generalized bang-bang results.