ppxscal/embedding_network huggingface dataset:
Numerical Approximations for Hereditary Systems with Input and OutputDelays: Convergence Results and Convergence Rates
Authors: A. Manitius, H. T. Tran
Venue: SIAM Journal on Control and Optimization (1994)

In this paper, the averaging approximation scheme for linear retarded functional differential equations with delays in control and observation is considered in the context of the state space theory developed by Pritchard and Salamon [SIAM J. Control Optim., 25 (1987), pp.~121--144]. Using known results from linear semigroup theory, convergence and estimate of convergence rate of the approximating semigroups are established. These extend results due to Banks and Burns [SIAM J. Control Optim., 16 (1978), pp.~169--208] and Lasiecka and Manitius [SIAM J. Numer. Anal., 25 (1988), pp.~883--907] on hereditary systems with delays in state, to the case when delays in control and observation are included. The main difference from the case when delays in input and output are excluded is that unbounded input and output operators must be dealt with in the abstract formulation. Moreover, in the presence of the unboundedness of the input and output operators, new convergence results of the state solutions and the output are also obtained.
Genetic algorithm based approach for designing computer network topology
Authors: Anup Kumar, Rakesh M. Pathak, M. C. Gupta
Venue: Proceedings of the 1993 ACM conference on Computer science (1993)

One of the important features of computer networks is the potential for high reliability. The reliability of a network depends on many parameters such as connectivity, degree of each node, and average distance between any pair of nodes. The main focus of the problem considered in this paper is to design reliable computer network topologies. A generalized framework based on Genetic Algorithm is developed which is applicable to wide range of network design problems. Several topology design problems are solved to demonstrate the generality of this solution approach. The results obtained from genetic algorithm based solution approach are compared with the optimal solutions to illustrate the effectiveness of the proposed approach.
Database research at AT T Bell Laboratories
Authors: H. V. Jagadish
Venue: ACM SIGMOD Record (1993)

Bell Laboratories is the Research and Development arm of AT T. There is today tremendous support for database research in Bell Labs and in AT T. This is expected to continue since database technology is recognized as being central not just to Teradata, NCR, and AT T's computing business but to its core communication business as well. What you see described below is a survey of the current state of a young and growing research effort in the database area. You should expect to see a stronger &ldquo;resume&rdquo; a few years down the road. Research at AT T Bell Labs is never directed from above, towards specific projects or objectives. Individual researchers select their areas of research based on a combination of factors that include individual skill and interest, other on-going activity and potential for collaboration, and the likelihood of intellectual or monetary impact. While research activity can range from the highly theoretical to the completely applied, it is expected that most research be performed within the framework of some larger objective; and this framework is typically provided by a prototype system. In addition to the core set of people here full-time, often there are visitors. You will see the names of many of these in the publications listed. For instance, most recently Oded Shmueli from the Technion spent a year with us. Currently, Avi Silberschatz is visiting from Austin.
Visual interaction design special interest area: notes from INTERCHI
Authors: Maria G. Wadlow
Venue: ACM SIGCHI Bulletin (1993)

Many of us weren't able to attend this year's conference in Amsterdam, myself included. So, for this column, Andy Cargile has volunteered to act as our INTERCHI '93 correspondent and give us a feel for this year's conference from a visual designer's perspective. Andy has done a fabulous job of blending facts and impressions to help recreate for us something of the experience that was INTERCHI '93.
Single logical view over enterprise-wide distributed databases
Authors: Andrew E. Wade
Venue: Proceedings of the 1993 ACM SIGMOD international conference on Management of data (1993)

Two trends in today's corporate world demand distribution: downsizing from centralized mainframe single database environments; and wider integration, connecting finance, engineering, manufacturing information systems for enterprise-wide modeling and operations optimization. The resulting environment consists of multiple databases, at the group level, department level, and corporate level, with the need to manage dependencies among data in all of them. The solution is full distribution, providing a single logical view to objects anywhere, from anywhere. Users see a logical model of objects connected to objects, with atomic transactions and propagating methods, even if composite objects are split among multiple databases, each under separate administrative control, on multiple, heterogeneous platforms, operating systems, and network protocols. Support for production environments includes multiple schemas, which may be shared among databases, private, or encrypted, dynamic addition of schemas, and schema evolution. Finally, the logical view must remain valid, and applications must continue to work, as the mapping to the physical environment changes, moving objects and databases to new platforms.
Incremental program testing using program dependence graphs
Authors: Samuel Bates, Susan Horwitz
Venue: Proceedings of the 20th ACM SIGPLAN-SIGACT symposium on Principles of programming languages (1993)

Program dependence graphs have been proposed for use in optimizing, vectorizing, and parallelizing compilers, and for program integration. This paper proposes their use as the basis for incremental program testing when using test data adequacy criteria. Test data adequacy is commonly used to provide some confidence that a particular test suite does a reasonable job of testing a program. Incremental program testing using test data adequacy criteria addresses the problem of testing a modified program given an adequate test suite for the original program. Ideally, one would like to create an adequate test suite for the modified program that reuses as many files from the old test suite as possible. Furthermore, one would like to know, for every file that is in both the old and the new test suites, whether the program components exercised by that file have been affected by the program modification; if no components have been affected, then it is not necessary to rerun the program using that file. In this paper we define adequacy criteria based on the program dependence graph, and propose techniques based on program slicing to identify components of the modified program that can be tested using files from the old test suite, and components that have been affected by the modification. This information can be used to reduce the time required to create new test files, and to avoid unproductive retesting of unaffected components. Although exact identification of the components listed above is, in general, undecidable, we demonstrate that our techniques provide safe approximations.
Queries-R-Links: graphical markup for text navigation
Authors: Gene Golovchinsky, Mark Chignell
Venue: Proceedings of the INTERACT '93 and CHI '93 conference on Human factors in computing systems (1993)

In this paper we introduce a style of interaction (interactive querying) that combines features of hypertext with Boolean querying, using direct markup of text to launch queries. We describe two experiments that compare the relative ease of expressing Boolean queries as text versus a graphical equivalent. The results of these experiments show that the expression of queries in the graphical format is no more difficult than the textual equivalent. We then describe the Queries-R-Links system that we have developed at the University of Toronto. Queries-R-Links uses the graphical markup method to launch Boolean queries interactively using direct markup of text. This work represents significant progress towards information exploration systems that combine the useful features of information retrieval querying and hypertext browsing.
IT in legal practice: research in progress
Authors: Leo van der Wees, Marleen Huysman
Venue: Proceedings of the 1994 computer personnel research conference on Reinventing IS : managing information technology in changing organizations: managing information technology in changing organizations (1994)

Information technology (IT) offers possibilities for legal practitioners not only as an aid in administrative processes but also for legal tasks. The former have been gradually automated particularly in larger firms but automation regarding the latter is still uncommon. Nevertheless, law firms could take advantage of their late start.A research project initiated by the Centre for Computers and Law of the Erasmus University Rotterdam will examine the application of IT to law firms. The project stresses the specific organizational aspects that need to be taken into account when dealing with the implementation of IT.The project addresses three research questions: the current state of law firms regarding their use of IT; what triggers or does not trigger law firms to make use of IT; how can IT be implemented within law firms without making the mistakes made by other businesses in which the implementation has been a failure.This research may well be of importance to the Dutch Bar as it has set the goal that all law firms must have reached a certain level of automation before the end of this century.
A note on inheritance and state machines
Authors: John D. McGregor, Douglas M. Dyer
Venue: ACM SIGSOFT Software Engineering Notes (1993)

The inheritance relationships in an object-oriented program have been shown to be a natural structure for facilitating reuse in a number of areas such as test cases. This note reports on a technique for incrementally building the state machine for a class from the state machines of its base classes. Using a style of state diagram similar to object charts provides a graphical means of displaying the resulting state machine. This incremental technique allows more complex machines to be built with less effort.
Using the run-time sizes of data structures to guide parallel-thread creation
Authors: Lorenz Huelsbergen, James R. Larus, Alexander Aiken
Venue: Proceedings of the 1994 ACM conference on LISP and functional programming (1994)

Dynamic granularity estimation is a new technique for automatically identifying expressions in functional languages for parallel evaluation. Expressions with little computation relative to thread-creation costs should evaluate sequentially for maximum performance. Static identification of such threads is however difficult. Therefore, dynamic granularity estimation has compile-time and run-time components: Abstract interpretation statically identifies functions whose complexity depends on data structure sizes; the run-time system maintains approximations to these sizes. Compiler-inserted checks consult this size information to make thread creation decisions dynamically.We describe dynamic granularity estimation for a list-based functional language. Extension to general recursive data structures and imperative operations is possible. Performance measurements of dynamic granularity estimation in a parallel ML implementation on a shared-memory machine demonstrate the possibility of large reductions (>20%) in execution time.
Automatic system file generator
Authors: Federico Vazquez, Guy Hanacek
Venue: ACM SIGSOFT Software Engineering Notes (1993)

The Advanced Automation System is a large complex system for Air Traffic Control used by the Federal Aviation Administration and its development is expected to last several years. Data Structure Design will change throughout the development cycle during these years. The Automatic System File Generator (ASFG) is designed to ease the effect of this continuous change in design in the area of Data Analysis. ASFG allows the creation of system files from thousands of message types whose structure is in continuous modification and revision.The basic purpose of the ASFG is to allow the input of any kind of message type files and convert them to system files for use by the Report System that is implemented with the Statistical Package for the Social Sciences (SPSS).
A concurrent copying garbage collector for languages that distinguish (im)mutable data
Authors: Lorenz Huelsbergen, James R. Larus
Venue: ACM SIGPLAN Notices (1993)

This paper describes the design and implementation of a concurrent compacting garbage collector for languages that distinguish mutable data from immutable data (e.g., ML) as well for languages that manipulate only immutable data (e.g., pure functional languages such as Haskell). The collector runs on shared-memory parallel computers and requires minimal mutator/collector synchronization. No special hardware or operating system support is required. Our concurrent collector derives from sequential semi-space copying collectors. The collector requires that a heap object includes forwarding pointer in addition to its data fields. An access to an immutable object can be satisfied either by the original or the forwarded copy of the object. A mutable object is always accessed through the forwarded copy, if one exists. Measurements of this collector in a Standard ML compiler on a shared-memory computer indicate that it eliminates perceptible garbage-collection pauses by reclaiming storage in parallel with the computation proper. All observed pause times are less than 20 milliseconds. We describe extensions for the concurrent collection of multiple mutator threads and refinements to our design that can improve its efficiency.
The Arnoldi Method for Normal Matrices
Authors: Thomas Huckle
Venue: SIAM Journal on Matrix Analysis and Applications (1994)

For large Hermitian matrices the preconditioned conjugate gradient algorithm and the Lanczos algorithm are the most important methods for solving linear systems and for computing eigenvalues. There are various generalizations to the nonsymmetric case based on the Arnoldi method or on the nonsymmetric Lanczos algorithm, e.g., generalized minimal residual ((GMRES), residual minimization in a Krylov space) and conjugate gradient squared ((CGS), a biorthogonalization algorithm adapted from the biconjugate gradient method) for linear equations and the incomplete orthogonalization method and the look-ahead Lanczos algorithm for computing eigenvalues. The aim of this paper is to analyse the Arnoldi method applied to a normal matrix. It is shown that for a normal matrix $A$, the Arnoldi projection $H_p$ is a normal upper Hessenberg matrix if and only if $A$ is (l)-normal. Only in this case, $H_p$ is tridiagonal and the Arnoldi method has the same properties as in the Hermitian case.
Reintroducing APL for teaching univariate and multivariate statistics
Authors: Steve Hunka
Venue: ACM SIGAPL APL Quote Quad (1994)

In teaching univariate and multivariate statistical analysis with an emphasis on the general linear model to graduate students in the social sciences, APL provides an excellent vehicle by which the concepts and operations of matrix algebra can be illustrated and explored. Functions written in APL to carry out the computations of the statistical models which provide for display of intermediate results allow students to check the adequacy of the final results and to confirm numerically the characteristics of the various models. When the objectives of a course are to provide for a basic understanding of the linear models, the use of APL is considered superior to the use of most commercial statistical packages.
Software environments for computer aided education
Authors: V. Gueraud, J. P. Cagnat, J. P. David, J. P. Pernin
Venue: ACM SIGCSE Bulletin (1994)

In the first part, we describe an example of an hypermedia tool for education, the Arcade laboratory. It illustrates our ideas about how to offer complementary resources to both teacher and student.In the second part, we analyze two kinds of production environment. The first one (Smalltalk) is based on the object-oriented approach: it reduces production work by making it easy to reuse predefined components, but it requires a good programming ability. The second one uses hypermedia software (HyperCard, ToolBook): it lets users produce small applications, even with a very minimal programming ability.In the last part, we describe our approach to improve both kinds of environment. Our final objective is to provide teachers with simple tools to adapt existing applications, or even to create new ones, so that they may easily integrate computer aided education in their daily practices.
The growth of software skill: a longitudinal look at learning performance
Authors: Erik Nilsen, HeeSen Jong, Judith S. Olson, Kevin Biolsi, Henry Rueter, Sharon Mutter
Venue: Proceedings of the INTERACT '93 and CHI '93 conference on Human factors in computing systems (1993)

This research follows a group of users over time (16 months) as they progress from novice towards expert in their use of Lotus 1-2-3. Quantitative and qualitative measures of performance are compared with expert users having over three years of experience. The results indicate that the motor aspects of performance are relatively stable over time, while improvement in the cognitive components of the skill are dependent on aspects of the menu structure and how many things must be retrieved from memory, among other things. These results imply extensions to the Keystroke Level Model of skilled performance as well as suggest ways to design the user interfaces so as to speed the acquisition of expertise.
Improving mentoring for women in computer science fields (abstract)
Authors: Anita Borg, J. Paul Myers,  Jr.
Venue: Proceedings of the 1993 ACM conference on Computer science (1993)

Can having a mentor influence the likelihood that a woman will succeed in establishing a career in computer science? A number of studies and reports suggest that an effective mentoring relationship can, indeed, make a difference in attracting women to academic and industrial careers in computer science and then keeping them in the field. In this panel, we will concentrate on practical issues such as training potential mentors in the requisite skills, matching proteges with mentors, incorporating or expanding a mentoring program within an institution, and special considerations for men mentoring women.
Isomorphism of Conflict Graphs in Multistage Interconnection Networks and its Application to Optimal Routing
Authors: Nabanita Das, Bhargab B. Bhattacharya, Jayasree Dattagupta
Venue: IEEE Transactions on Computers (1993)

A study on the isomorphism of conflict graphs in multistage interconnection networks (MINs) and its applications is outlined. A concept called group-transformation is introduced for the baseline network, which induces an equivalence partition on the set of all permutations. All members belonging to the same equivalence class have isomorphic conflict graphs. Thus, determination of conflict resolution of one permutation results in determination of conflict resolution of all other equivalent members. The BPCL (bit-permute-closure) class of permutations is defined, for which the conflict resolution problem can be settled in linear time by an earlier algorithm developed only for the BPC (bit-permute-complement) permutations. It is proved that for an N*N MIN, mod BPCL mod
Extensible file systems in spring
Authors: Yousef A. Khalidi, Michael N. Nelson
Venue: Proceedings of the fourteenth ACM symposium on Operating systems principles (1994)

In this paper we describe an architecture for extensible file systems. The architecture enables the extension of file system functionality by composing (or stacking) new file systems on top of existing file systems. A file system that is stacked on top of an existing file system can access the existing file system's files via a well-defined naming interface and can share the same underlying file data in a coherent manner. We describe extending file systems in the context of the Spring operating system. Composing file systems in Spring is facilitated by basic Spring features such as its virtual memory architecture, its strongly-typed well-defined interfaces, its location-independent object invocation mechanism, and its flexible naming architecture. File systems in Spring can reside in the kernel, in user-mode, or on remote machines, and composing them can be done in a very flexible manner.
EWHCI '93 (East-West international conference on Human-Computer Interaction): conference report, Moscow, Russia, August 3&ndash;7
Authors: Keith Instone, Allen Cypher, Claus Unger
Venue: ACM SIGCHI Bulletin (1994)

The third annual East-West Human-Computer Interaction conference was held in Moscow in early August, 1993. The first meeting of this kind was a single-track symposium held just before the collapse of the USSR in 1991; the second used the East-West name and was held in St. Petersburg in 1992. The conference took place at the International Centre for Scientific and Technical Information (ICSTI), ICSTI, led by Juri Gornostaev, served as the Russian organizers of the conference. The western organization was chaired by Austin Henderson, with Len Bass and Claus Unger serving as the technical program chairs.
Experience with fine-grain synchronization in MIMD machines for preconditioned conjugate gradient
Authors: Donald Yeung, Anant Agarwal
Venue: ACM SIGPLAN Notices (1993)

This paper discusses our experience with fine-grain synchronization for a variant of the preconditioned conjugate gradient method. This algorithm represents a large class of algorithms that have been widely used but traditionally difficult to implement efficiently on vector and parallel machines. Through a series of experiments conducted using a simulator of a distributed shared-memory multiprocessor, this paper addresses two major questions related to fine-grain synchronization in the context of this application. First, what is the overall impact of fine-grain synchronization on performance? Second, what are the individual contributions of the following three mechanisms typically provided to support fine-grain synchronization: language-level support, full-empty bits for compact storage and communication of synchronization state, and efficient processor operations on the state bits? Our expereiments indicate that fine-grain synchronization improves overall performancey by a factor of 3.7 on 16 processors using the largest problem size we could simulate; we project that significant performance advantage will be sustained for larger problem sizes. We also show that the bulk of the performance advantage for this application can be attributed to exposing increased parallelism through language-level expression of fine-grain synchronization. A smaller fraction relies on a compact implementation of synchronization state, while an even smaller fraction results from efficient full-empty bit operations.
Static slicing in the presence of goto statements
Authors: Jong-Deok Choi, Jeanne Ferrante
Venue: ACM Transactions on Programming Languages and Systems (TOPLAS) (1994)

A static program slice is an extract of a program which can help our understanding of the behavior of the program; it has been proposed for use in debugging, optimization, parallelization, and integration of programs. This article considers two types of static slices: executable and nonexecutable. Efficient and well-founded methods have been developed to construct executable slices for programs without goto statements; it would be tempting to assume these methods would apply as well in programs with arbitrary goto statements. We show why previous methods do not work in this more general setting, and describe our solutions that correctly and efficiently compute executable slices for programs even with arbitrary goto statements. Our conclusion is that goto statements can be accommodated in generating executable static slices.