ppxscal/embedding_network huggingface dataset:
Rectangle-packing-based module placement
Authors: Hiroshi Murata, Kunihiro Fujiyoshi, Shigetoshi Nakatake, Yoji Kajitani
Venue: Proceedings of the 1995 IEEE/ACM international conference on Computer-aided design (1995)

The first and the most critical stage in VLSI layout design is the placement, the background of which is the rectangle packing problem: Given many rectangular modules of arbitrary size, place them without overlapping on a layer in the smallest bounding rectangle. Since the variety of the packing is infinite (two- dimensionally continuous) many, the key issue for successful optimization is in the introduction of a P-admissible solution space, which is a finite set of solutions at least one of which is optimal. This paper proposes such a solution space where each packing is represented by a pair of module name sequences. Searching this space by simulated annealing, hundreds of modules could be successfully packed as demonstrated. Combining a conventional wiring method, the biggest MCNC benchmark ami49 is challenged.
Performance evaluation of the PowerPC 620 microarchitecture
Authors: Trung A. Diep, Christopher Nelson, John Paul Shen
Venue: ACM SIGARCH Computer Architecture News (1995)

The PowerPC 620 trade; microprocessor is the most recent and performance leading member of the PowerPC trade; family. The 64-bit PowerPC 620 microprocessor employs a two-phase branch prediction scheme, dynamic renaming for all the register files, distributed multi-entry reservation stations, true out-of-order execution by six execution units, and a completion buffer for ensuring precise exceptions. This paper presents an instruction-level performance evaluation of the 620 microarchitecture. A performance simulator is developed using the VMW (Visualization-based Microarchitecture Workbench) retargetable framework. The VMW-based simulator accurately models the microarchitecture down to the machine cycle level. Extensive trace-driven simulation is performed using the SPEC92 benchmarks. Detailed quantitative analyses of the effectiveness of all key microarchitecture features are presented.
SCIRun: a scientific programming environment for computational steering
Authors: Steven G. Parker, Christopher R. Johnson
Venue: Proceedings of the 1995 ACM/IEEE conference on Supercomputing (CDROM) (1995)

We present the design, implementation and application of SCIRun, a scientific programming environment that allows the interactive construction, debugging and steering of large scale scientific computations. Using this "computational workbench," a scientist can design and modify simulations interactively via a dataflow programming model. SCIRun enables scientists to design and modify models and automatically change parameters and boundary conditions as well as the mesh discretization level needed for an accurate numerical solution. As opposed to the typical "off-line" simulation mode - in which the scientist manually sets input parameters, computes results, visualizes the results via a separate visualization package, then starts again at the beginning - SCIRun "closes the loop" and allows interactive steering of the design and computation phases of the simulation. To make the dataflow programming paradigm applicable to large scientific problems, we have identified ways to avoid the excessive memory use inherent in standard dataflow implementations, and have implemented fine-grained dataflow in order to further promote computational efficiency. In this paper, we describe applications of the SCIRun system to several problems in computational medicine. In addition, an we have included an interactive demo program in the form of an application of SCIRun system to a small electrostatic field problem.
The complexity of logic-based abduction
Authors: Thomas Eiter, Georg Gottlob
Venue: Journal of the ACM (JACM) (1995)

Abduction is an important form of nonmonotonic reasoning allowing one to find explanations for certain symptoms or manifestations. When the application domain is described by a logical theory, we speak about logic-based abduction. Candidates for abductive explanations are usually subjected to minimality criteria such as subset-minimality, minimal cardinality, minimal weight, or minimality under prioritization of individual hypotheses. This paper presents a comprehensive complexity analysis of relevant decision and search problems related to abduction on propositional theories. Our results indicate that abduction is harder than deduction. In particular, we show that with the most basic forms of abduction the relevant decision problems are complete for complexity classes at the second level of the polynomial hierarchy, while the use of prioritization raises the complexity to the third level in certain cases.
Improving data locality with loop transformations
Authors: Kathryn S. McKinley, Steve Carr, Chau-Wen Tseng
Venue: ACM Transactions on Programming Languages and Systems (TOPLAS) (1996)

In the past decade, processor speed has become significantly faster than memory speed. Small, fast cache memories are designed to overcome this discrepancy, but they are only effective when programs exhibit data locality. In the this article, we present compiler optimizations to improve data locality based on a simple yet accurate cost model. The model computes both temporal and spatial reuse of cache lines to find desirable loop organizations. The cost model drives the application of compound transformations consisting of loop permutation, loop fusion, loop distribution, and loop reversal. To validate our optimization strategy, we implemented our algorithms and ran experiments on a large collection of scientific programs and kernels. Experiments illustrate that for kernels our model and algorithm can select and achieve the best loop structure for a nest. For over 30 complete applications, we executed the original and transformed versions and simulated cache hit rates. We collected statistics about the inherent characteristics of these programs and our ability to improve their data locality. To our knowledge, these studies are the first of such breadth and depth. We found performance improvements were difficult to achieve bacause benchmark programs typically have high hit rates even for small data caches; however, our optimizations significanty improved several programs.
On configuring a single disk continuous media server
Authors: Shahram Ghandeharizadeh, Seon Ho Kim, Cyrus Shahabi
Venue: ACM SIGMETRICS Performance Evaluation Review (1995)

The past decade has witnessed a proliferation of repositories that store and retrieve continuous media data types, e.g., audio and video objects. These repositories are expected to play a major role in several emerging applications, e.g., library information systems, educational applications, entertainment industry, etc. To support the display of a video object, the system partitions each object into fixed size blocks. All blocks of an object reside permanently on the disk drive. When displaying an object, the system stages the blocks of the object into memory one at a time for immediate display. In the presence of multiple displays referencing different objects, the bandwidth of the disk drive is multiplexed among requests, introducing disk seeks. Disk seeks reduce the useful utilization of the disk bandwidth and result in a lower number of simultaneous displays (throughput).This paper characterizes the impact of disk seeks on the throughput of the system. It describes REBECA as a mechanism that maximizes the throughput of the system by minimizing the time attributed to each incurred seek. A limitation of REBECA is that it increases the latency observed by each request. We quantify this throughput vs latency tradeoff of REBECA and, develop an efficient technique that computes its configuration parameters to realize the performance requirements (desired latency and throughput) of an application.
Efficient fair queueing using deficit round robin
Authors: M. Shreedhar, George Varghese
Venue: ACM SIGCOMM Computer Communication Review (1995)

Fair queuing is a technique that allows each flow passing through a network device to have a fair share of network resources. Previous schemes for fair queuing that achieved nearly perfect fairness were expensive to implement: specifically, the work required to process a packet in these schemes was O(log(n)), where n is the number of active flows. This is expensive at high speeds. On the other hand, cheaper approximations of fair queuing that have been reported in the literature exhibit unfair behavior. In this paper, we describe a new approximation of fair queuing, that we call Deficit Round Robin. Our scheme achieves nearly perfect fairness in terms of throughput, requires only O(1) work to process a packet, and is simple enough to implement in hardware. Deficit Round Robin is also applicable to other scheduling problems where servicing cannot be broken up into smaller units, and to distributed queues.
A Syntactic Theory of Software Architecture
Authors: Thomas R. Dean, James R. Cordy
Venue: IEEE Transactions on Software Engineering (1995)

In this paper we introduce a general, extensible diagrammatic syntax for expressing software architectures based on typed nodes and connections and formalized using set theory. The syntax provides a notion of abstraction corresponding to the concept of a subsystem, and exploits this notion in a general mechanism for pattern matching over architectures. We demonstrate these ideas using a small example architecture language with a limited number of types of nodes and connectors, and a small taxonomy of architectures characterized as sets of patterns in the language.
Designs and Codes: An update
Authors: E. F. Assmus,  Jr.
Venue: Designs, Codes and Cryptography (1996)

Since the publication in 1992 of ``Designs and their Codes" significant progress has been made in the general area of codes coming from designs. This article reviews this progress and presents some of the results &mdash; including confirmation of certain conjectures made and answers to some of the questions raised in the book.
A Nonlinear Mixed Finite Eelement Method for a Degenerate Parabolic Equation Arising in Flow in Porous Media
Authors: Todd Arbogast, Mary F. Wheeler, Nai-Ying Zhang
Venue: SIAM Journal on Numerical Analysis (1996)

We study a model nonlinear, degenerate, advection-diffusion equation having application in petroleum reservoir and groundwater aquifer simulation. The main difficulty is that the true solution is typically lacking in regularity; therefore, we consider the problem from the point of view of optimal approximation. Through time integration, we develop a mixed variational form that respects the known minimal regularity, and then we develop and analyze two versions of a mixed finite element approximation, a simpler semidiscrete (time-continuous) version and a fully discrete version. Our error bounds are optimal in the sense that all but one of the bounding terms reduce to standard approximation error. The exceptional term is a nonstandard approximation error term. We also consider our new formulation for the nondegenerate problem, showing the usual optimal $L_2$-error bounds; moreover, superconvergence is obtained under special circumstances.
Institutional impacts on decision support system research
Authors: Clyde W. Holsapple, Wenhong Luo
Venue: ACM SIGMIS Database (1995)

This research extends a recent study that ranked the contributions of doctoral MIS institutions to decision support system research. That ranking was based on the frequency with which work of an institution's faculty has been cited in reference lists of a large set of DSS journal articles appearing over a 20-year period. We contend that this frequency measure of an institution's contribution is only one way of measuring its impact on decision support system research. Another impact measure involves the potency of an institution's contributions. Here, we develop an institutional ranking based on this alternative impact measure. Results of the frequency and potency rankings are then combined into an overall impact index for assessing relative contributions. Finally, we normalize the impact rankings with respect to faculty size.
A Well-Behaved Enumeration of Star Graphs
Authors: Nader Bagherzadeh, Martin Dowd, Shahram Latifi
Venue: IEEE Transactions on Parallel and Distributed Systems (1995)

An enumeration of star graphs is given which has many useful properties. For example an arbitrary prefix or suffix is connected; indeed the diameter is $O(n)$. As a consequence, there is an $O(n)$ interval broadcast algorithm. Prefixes which have $t(n-1)!$ vertices for some $t$ are especially well-behaved. The topology of, embeddings in, and algorithms for these graphs are considered, making use of the enumeration.Index Terms¿Interconnection network, star graph, incomplete star graph, interval broadcast, Hamiltonian cycles.
An Active Testing Model for Tracking Roads in Satellite Images
Authors: Donald Geman, Bruno Jedynak
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1996)

We present a new approach for tracking roads from satellite images, and thereby illustrate a general computational strategy ("active testing") for tracking 1D structures and other recognition tasks in computer vision. Our approach is related to recent work in active vision on "where to look next" and motivated by the "divide-and-conquer" strategy of parlor games such as "Twenty Questions." We choose "tests" (matched filters for short road segments) one at a time in order to remove as much uncertainty as possible about the "true hypothesis" (road position) given the results of the previous tests. The tests are chosen on-line based on a statistical model for the joint distribution of tests and hypotheses. The problem of minimizing uncertainty (measured by entropy) is formulated in simple and explicit analytical terms. To execute this entropy testing rule we then alternate between data collection and optimization: At each iteration new image data are examined and a new entropy minimization problem is solved (exactly), resulting in a new image location to inspect, and so forth. We report experiments using panchromatic SPOT satellite imagery with a ground resolution of ten meters: Given a starting point and starting direction, we are able to rapidly track highways in southern France over distances on the order of one hundred kilometers without manual intervention.
Learning from a Population of Hypotheses
Authors: Michael Kearns, H. Sebastian Seung
Venue: Machine Learning (1995)

We introduce a new formal model in which a learning algorithm must combine a collection of potentially poor but statistically independent hypothesis functions in order to approximate an unknown target function arbitrarily well. Our motivation includes the question of how to make optimal use of multiple independent runs of a mediocre learning algorithm, as well as settings in which the many hypotheses are obtained by a distributed population of identical learning agents.
Fast Legendre--Fenchel Transform and Applications to Hamilton--Jacobi Equations and Conservation Laws
Authors: Lucilla Corrias
Venue: SIAM Journal on Numerical Analysis (1996)

We are interested in the study of a fast algorithm introduced by Brenier computing the discrete Legendre--Fenchel transform of a real function. We present convergence results and show how the order of convergence grows with the regularity of the function to be transformed. Applications to Hamilton--Jacobi equations for front propagation problems and conservation laws are presented.
K12 and the web
Authors: Susan A. Mengel
Venue: ACM SIGICE Bulletin (1995)

K12 resources on and uses of the internet are becoming plentiful. Previously many home pages on the World Wide Web (WWW) were only text, but now students have created colorful graphics and even movies for the Web. The excitement of the students is contagious and, as a result, many schools have allowed part of their home pages to be designed by the students themselves. This paper discusses how students are gaining access to the internet and how educators are enabling that access to happen.
Fragmentation considered harmful
Authors: Christopher A. Kent, Jeffrey C. Mogul
Venue: ACM SIGCOMM Computer Communication Review (1995)

Internetworks can be built from many different kinds of networks, with varying limits on maximum packet size. Throughput is usually maximized when the largest possible packet is sent; unfortunately, some routes can carry only very small packets. The IP protocol allows a gateway to fragment a packet if it is too large to be transmitted. Fragmentation is at best a necessary evil; it can lead to poor performance or complete communication failure. There are a variety of ways to reduce the likelihood of fragmentation; some can be incorporated into existing IP implementations without changes in protocol specifications. Others require new protocols, or modifications to existing protocols.
A Family of Fault-Tolerant Routing Protocols for Direct Multiprocessor Networks
Authors: Patrick T. Gaughan, Sudhakar Yalamanchili
Venue: IEEE Transactions on Parallel and Distributed Systems (1995)

Our goal is to reconcile the conflicting demands of performance and fault-tolerance in interprocessor communication. To this end, we propose a pipelined communication mechanism¿pipelined circuit-switching (PCS)¿which is a variant of the well known wormhole routing (WR) mechanism. PCS relaxes some of the routing constraints imposed by WR and as a result enables routing behavior that cannot otherwise be realized. This paper presents a new class of adaptive routing algorithms¿misrouting backtracking with $m$ misroutes (MB-$m$). This class of routing algorithms is made possible by PCS. We provide an analysis of the performance and static fault-tolerant properties of MB-$m$. The results of an experimental evaluation of PCS and MB-3 are also presented. This methodology provides performance approaching that of WR, while realizing a level of resilience to static faults that is difficult to achieve with WR.
Teaching computer science: experience from four continents
Authors: Mats Daniels, Judith Gal-Ezer, Ian Sanders, G. Joy Teague
Venue: ACM SIGCSE Bulletin (1996)

In this paper we compare and contrast computer science curricula in four universities in four different countries (and continents): Australia; Israel; South Africa and Sweden. Uppsala University in Sweden is a European university founded in 1477 with a long history of tradition. The University of Witwatersrand in South Africa and Deakin University in Australia evolved from 'Schools of Mines' (technical schools) in 1922 and 1977 respectively and have their roots in the British academic system. The Open University of Israel, established in 1974 by the Ministry of Education, began teaching in 1976. As new universities, Deakin University and the Open University of Israel sought to fill needs not met by existing universities, so both have concentrated on distance learning (off-campus) programs. For similar reasons, Deakin University and the Open University of Israel also provide special non-degree short courses and programs. We refer to undergraduate and graduate studies and consider degree requirements, methods of delivery, assessment, and costs. We also briefly mention such issues as programming languages and the development and evolution of programs of study and of individual courses in the four universities.
Management and utilization of knowledge for the automatic improvement of workflow performance
Authors: Trent Jaeger, Atul Prakash
Venue: Proceedings of conference on Organizational computing systems (1995)

We present a framework that enables reengineers to build a base of performance improvement knowledge that can be used to automatically improve workflow performance. Automatic improvement of workflow performance involves modification of a business information system such that the predicted performance of its business workflows satisfies a performance goal. The number of possible modification options is very large, so a significant body of knowledge is needed to choose among them. We demonstrate, using a simple example, the requirements for the types of knowledge necessary in a automatic improvement framework. We define a knowledge model for representing these types of knowledge. We use the model to provide the framework with a body of domain-independent performance improvement knowledge. We then describe how the framework enables reengineers to provide additional performance improvement knowledge to the model and how the framework utilizes that knowledge to automatically improve workflow performance to meet the performance goal.
Exotica: a project on advanced transaction management and workflow systems
Authors: C. Mohan, D. Agrawal, G. Alonso, A. El Abbadi, R. Guenthoer, M. Kamath
Venue: ACM SIGOIS Bulletin (1995)

This paper is an overview of the Exotica project, currently in progress at the IBM Almaden Research Center. The project aims at exploring several research areas from advanced transaction management concepts to client/server architectures and mobile computing within the context of business processes and workflow management. The ultimate goal is to incorporate these ideas into IBM's products and prototypes. The project involves IBM groups in Almaden (U.S.A.), Hursley (U.K.), Boeblingen (Germany), and Vienna (Austria). In this paper we briefly describe two IBM products, FlowMark, a workflow management system, and MQSeries, a messaging system, as the environments in which we are focusing our research. We also discuss some of our results in the areas of availability, replication, distribution, and advanced transaction models, as well as describe our future research directions. 10
The Serial Transitive Closure Problem for Trees
Authors: Maria Luisa Bonet, Samuel R. Buss
Venue: SIAM Journal on Computing (1995)

The serial transitive closure problem is the problem of, given a directed graph $G$ and a list of edges, called closure edges, which are in the transitive closure of the graph, to generate all the closure edges from edges in $G$. A nearly linear upper bound is given on the number of steps in optimal solutions to the serial transitive closure problem for the case of graphs which are trees. "Nearly linear" means $O(n\cdot \alpha(n))$ where $\alpha$ is the inverse Ackermann function. This upper bound is optimal to within a constant factor.
Data Security Equals Graph Connectivity
Authors: Ming-Yang Kao
Venue: SIAM Journal on Discrete Mathematics (1996)

To protect sensitive information in a cross-tabulated table, it is a common practice to suppress some of the cells in the table. This paper investigates four levels of data security of a two-dimensional table concerning the effectiveness of this practice. These four levels of data security protect the information contained in, respectively, individual cells, individual rows and columns, several rows or columns as a whole, and a table as a whole. The paper presents efficient algorithms and NP-completeness results for testing and achieving these four levels of data security. All these complexity results are obtained by means of fundamental equivalences between the four levels of data security of a table and four types of connectivity of a graph constructed from that table.
Computational geometry column 28
Authors: Joseph O'Rourke
Venue: ACM SIGACT News (1996)

The Web directory of Computational Geometry Software is described.