ppxscal/embedding_network huggingface dataset:
A naming convention for classes in Ada 9X
Authors: J.-P. Rosen
Venue: ACM SIGAda Ada Letters (1995)

This paper discusses a problem encountered when using generics for faceted OOP in Ada 9X, and proposes a general naming scheme for classes that provides a convenient and readable solution to this problem.
An empirical comparison of a hypertext-based systems analysis case with conventional cases and role playing
Authors: Julie E. Kendall, Kenneth E. Kendall Richard L. Baskerville, Raymond J. Barnes
Venue: ACM SIGMIS Database (1996)

Systems analysis and design is a practical discipline, difficult to teach realistically with conventional methods. HyperCase is an interactive program that presents an organization called Maple Ridge Engineering in a highly graphical environment for use on a microcomputer. Use of hypertext allows students to navigate through the organization, doing interviews, and examining diagrams in the order they prefer, rather than in the prescribed, linear fashion found in conventional cases.The effectiveness of HyperCase versus conventional cases and role playing in helping students reach six different levels of educational objectives was assessed in an experiment with 22 students. Those using HyperCase performed as well or better on the examination questions than those using standard approaches. In the second part of the study, results from an affective student questionnaire completed by the original 22 students, plus 97 others, revealed that they were overwhelmingly positive in their reaction to this new approach. Little difference in the reactions among experienced and inexperienced computer users was found. Based on our empirical findings, we conclude that students felt their experience with HyperCase was an important departure from the traditional systems analysis and design class.
Efficiency of algorithms for programming beginners
Authors: David Ginat
Venue: ACM SIGCSE Bulletin (1996)

Introductory computer science courses often present the concept of algorithm efficiency in a rather late stage, through searching and sorting problems. We believe that the concept of efficiency can be presented much earlier. In this paper we present a novel approach in which efficiency of algorithms is presented early, gradually and intuitively. We link our approach to cognitive consequences of programming instruction and illustrate it with three problems.We implemented our approach with 10th and 11th grade high-school students. In the paper, we describe our experience with posing the three problems to the students. Student solutions varied considerably, reflecting different levels of insight into the problems. The various solutions led to fruitful class discussions, thus widening the students' repertoire of templates, and enhancing student realization as to the importance of analysis and planning.
Modechart: A Specification Language for Real-Time Systems
Authors: Farnam Jahanian, Aloysius K. Mok
Venue: IEEE Transactions on Software Engineering (1994)

Present a specification language for real-time systems called Modechart. The semantics of Modechart is given in terms of real-time logic (RTL), which is especially amenable to reasoning about the absolute (real-time clock) timing of events. The semantics of Modechart has an important property that the translation of a Modechart specification into RTL formulas results in a hierarchical organization of the resulting RTL assertions. This gives us significant leverage in reasoning about properties of a system by allowing us to filter out assertions that concern lower levels of abstraction. Some results about desirable properties of Modechart specifications are given. A graphical implementation of Modechart has been completed.
Approximate mean value analysis algorithms for queuing networks: existence, uniqueness, and convergence results
Authors: K. R. Pattipati, M. M. Kostreva, J. L. Teele
Venue: Journal of the ACM (JACM) (1990)

This paper is concerned with the properties of nonlinear equations associated with the Scheweitzer-Bard (S-B) approximate mean value analysis (MVA) heuristic for closed product-form queuing networks. Three forms of nonlinear S-B approximate MVA equations in multiclass networks are distinguished: Schweitzer, minimal, and the nearly decoupled forms. The approximate MVA equations have enabled us to: (a) derive bounds on the approximate throughput; (b) prove the existence and uniqueness of the S-B throughput solution, and the convergence of the S-B approximation algorithm for a wide class of monotonic, single-class networks; (c) establish the existence of the S-B solution for multiclass, monotonic networks; and (d) prove the asymptotic (i.e., as the number of customers of each class tends to &infin;) uniqueness of the S-B throughput solution, and (e) the convergence of the gradient projection and the primal-dual algorithms to solve the asymptotic versions of the minimal, the Schweitzer, and the nearly decoupled forms of MVA equations for multiclass networks with single server and infinite server nodes. The convergence is established by showing that the approximate MVA equations are the gradient vector of a convex function, and by using results from convex programming and the convex duality theory.
Feedback Laws for Nonlinear Distributed Control Problems via Trotter-Type Product Formulae
Authors: Catalin Popa
Venue: SIAM Journal on Control and Optimization (1995)

A feedback law expressed by means of a Trotter product formula approximation of the dynamic programming equation, and which provides approximately optimal controls, is established for the control systems governed by a certain class of variational inequalities of parabolic type. To this purpose, two general Lie-Trotter formulas for the dynamic programming equation are proposed, and corresponding convergence results (generalizing previous results of the author) are proved. The framework also includes the control systems described by the parabolic obstacle problem as well as those governed by semilinear parabolic equations.
A visual retrieval environment for hypermedia information systems
Authors: Dario Lucarella, Antonella Zanzi
Venue: ACM Transactions on Information Systems (TOIS) (1996)

We present a graph-based object model that may be used as a uniform framework for direct manipulation of multimedia information. After an introduction motivating the need for abstraction and structuring mechanisms in hypermedia systems, we introduce the data model and the notion of perspective, a form of data abstraction that acts as a user interface to the system, providing control over the visibility of the objects and their properties. A perspective is defined to include an intension and an extension. The intension is defined in terms of a pattern, a subgraph of the schema graph, and the extension is the set of pattern-matching instances. Perspectives, as well as database schema and instances, are graph structures that can be manipulated in various ways. The resulting uniform approach is well suited to a visual interface. A visual interface for complex information systems provides high semantic power, thus exploiting the semantic expressibility of the underlying data model, while maintaining ease of interaction with the system. In this way, we reach the goal of decreasing cognitive load on the user, with the additional advantage of always maintaining the same interaction style. We present a visual retrieval environment that effectively combines filtering, browsing, and navigation to provide an integrated view of the retrieval problem. Design and implementation issues are outlined for MORE (Multimedia Object Retrieval Environment), a prototype system relying on the proposed model. The focus is on the main user interface functionalities, and actual interaction sessions are presented including schema creation, information loading, and information retrieval.
Stack caching for interpreters
Authors: M. Anton Ertl
Venue: ACM SIGPLAN Notices (1995)

An interpreter can spend a significant part of its execution time on accessing arguments of virtual machine instructions. This paper explores two methods to reduce this overhead for virtual stack machines by caching top-of-stack values in (real machine) registers. The dynamic method is based on having, for every possible state of the cache, one specialized version of the whole interpreter; the execution of an instruction usually changes the state of the cache and the next instruction is executed in the version corresponding to the new state. In the static method a state machine that keeps track of the cache state is added to the compiler. Common instructions exist in specialized versions for several states, but it is not necessary to have a version of every instruction for every cache state. Stack manipulation instructions are optimized away.
Software development using domain-specific software architectures: CDRl A011&mdash;a curriculum module in the SEI style
Authors: Richard N. Taylor, Will Tracz, Lou Coglianese
Venue: ACM SIGSOFT Software Engineering Notes (1995)

The objective of software development using domain-specific software architectures (DSSA) is reduction in time and cost of producing specific application systems within a supported domain, along with increased product quality, improved manageability, and positioning for acquisition of future business. Key aspects of the approach include software reuse based on parameterization of generic components and interconnection of components within a canonical solution framework. Viability of the approach depends on identification and deep understanding of a selected domain of applications. The DSSA approach, to be effectively applied, requires a variety of support tools, including repository mechanisms, prototyping facilities, and analysis tools. This curriculum module describes the DSSA approach, representative examples, supporting tools, and processes.
Using computer simulation to reengineer traditional stove-piped army staffs for information operations in the 21st century
Authors: Michael L. McGinnis, Robert G. Phelan,  Jr.
Venue: Proceedings of the 27th conference on Winter simulation (1995)

Recently, the US Army has been confronted by a wider range of military and peace-keeping operations. The future success of the Army on tomorrow's battlefields depends, in part, on how effectively our forces are able to fight and win the information war. We present a computer simulation approach being developed for the Army Digitization Office (ADO) for reengineering the current stove-piped organization of tactical Army staffs into staffs organized for information operations in the 21st century.
Using the SLEDGE package on Sturm-Liouville problems having nonempty essential spectra
Authors: Michael S. P. Eastham, Charles T. Fulton, Steven Pruess
Venue: ACM Transactions on Mathematical Software (TOMS) (1996)

We describe the performance of the Sturm-Liouville software package SLEDGE on a variety of problems having continuous spectra. The code's output is shown to be in good accord with a wide range of known theoretical results.
Analysis of Costate Discretizations in Parameter Estimation for Linear Evolution Equations
Authors: C. R. Vogel, J. G. Wade
Venue: SIAM Journal on Control and Optimization (1995)

A widely used approach to parameter identification is the output least-squares formulation. Numerical methods for solving the resulting minimization problem almost invariably require the computation of the gradient of the output least-squares functional. When the identification problem involves time-dependent distributed parameter systems (or approximations thereof), numerical evaluation of the gradient can be extremely time consuming. The costate method can greatly reduce the cost of computing these gradients. However, questions have been raised concerning the accuracy and convergence of costate approximations, even when the numerical methods being used are known to converge rapidly on the forward problem. In this paper it is shown that the use of time-marching schemes that yield high-order accuracy on the forward problem does not necessarily lead to high-order accurate costate approximations. In fact, in some cases these approximations do not converge at all. However, under certain circumstances, rapidly converging gradient approximations do result because of rapid weak-star-type convergence of the costate approximations. These issues are treated both theoretically and numerically.
Stability of Linear Equations Solvers in Interior-Point Methods
Authors: Stephen J. Wright
Venue: SIAM Journal on Matrix Analysis and Applications (1995)

Primal-dual interior-point methods for linear complementarity and linear programming problems solve a linear system of equations to obtain a modified Newton step at each iteration. These linear systems become increasingly ill-conditioned in the later stages of the algorithm, but the computed steps are often sufficiently accurate to be useful. We use error analysis techniques tailored to the special structure of these linear systems to explain this observation and examine how theoretically superlinear convergence of a path-following algorithm is affected by the roundoff errors.
Input/output characteristics of scalable parallel applications
Authors: Phyllis E. Crandall, Ruth A. Aydt, Andrew A. Chien, Daniel A. Reed
Venue: Proceedings of the 1995 ACM/IEEE conference on Supercomputing (CDROM) (1995)

Rapid increases in computing and communication performance are exacerbating the long-standing problem of performance-limited input/output. Indeed, for many otherwise scalable parallel applications. input/output is emerging as a major performance bottleneck. The design of scalable input/output systems depends critically on the input/output requirements and access patterns for this emerging class of large-scale parallel applications. However, hard data on the behavior of such applications is only now becoming available. In this paper, we describe the input-output requirements of three scalable parallel applications (electron scattering, terrain rendering, and quantum chemistry, on the Intel Paragon XP/S. As part of an ongoing parallel input/output characterization effort, we used instrumented versions of the application codes to capture and analyze input/output volume, request size distributions, and temporal request structure. Because complete traces of individual application input/output requests were captured, in-depth, off-line analyses were possible. In addition, we conducted informal interviews of the application developers to understand the relation between the codes' current and desired input/output structure. The results of our studies show a wide variety of temporal and spatial access patterns, including highly read-intensive and write-intensive phases, extremely large and extremely small request sizes, and both sequential and highly irregular access patterns. We conclude with a discussion of the broad spectrum of access patterns and their profound implications for parallel file caching and prefetching schemes.
Image processing as an exemplar of parallelism applied to graphics
Authors: Harry F. Smith, Patrick Plusnick, Mark Sarojak, William Seitz
Venue: ACM SIGCSE Bulletin (1996)

In surveying the possible applications of parallel computing, computer graphics is singularly attractive. This is because many computer graphics algorithms are so computationally intensive and yet also inherently very parallel in nature. The primary objective of an NSF grant to the University of North Carolina at Wilmington was to establish parallel computing in the undergraduate curriculum. A secondary objective was to address the issue of parallelism for computer graphics; however, curricular constraints made this difficult to do. Our response to this difficulty was twofold. For one, we focused on image processing as a more accessible, but very significant, alternative to ordinary computer graphics. Also, as a means of enabling deeper student involvement, we were able to supplement the original equipment grant (ILI) with one for supporting student research (REU).
Embedding Classical Communication Topologies in the Scalable OPAM Architecture
Authors: Amnon Barak, Eugen Schenfeld
Venue: IEEE Transactions on Parallel and Distributed Systems (1996)

This paper presents novel embeddings of various classical topologies into the OPAM multicomputer. OPAM consists of a large number of processors that are connected by a two level, crossbar based interconnection network. The network combines a large, optical circuit-switched crossbar (reconfigurable network), with many small, packet-switching crossbars. The needed embedding is very different than the classical approaches. The goal in our case is to minimize routing decisions, so that communication requests can be satisfied by passing through two small crossbars. We show how to map parallel programs to this architecture using graph contraction notations. The family of parallel programs that we consider consists of multiple processes and communication links that are represented by connected, regular graphs such as rings, trees, two dimensional grids, cube connected cycles and hypercubes. In each case we show how to partition the vertex set of the program's graph to subsets, and how to assign each subset a cluster of processors in order to realize the topology of the given problem. In some of the cases we also prove that our partition and assignment algorithms are optimal.
A syntactic analysis method of long Japanese sentences based on the detection of conjunctive structures
Authors: Sadao Kurohashi, Makoto Nagao
Venue: Computational Linguistics (1994)

This paper presents a syntactic analysis method that first detects conjunctive structures in a sentence by checking parallelism of two series of words and then analyzes the dependency structure of the sentence with the help of the information about the conjunctive structures. Analysis of long sentences is one of the most difficult problems in natural language processing. The main reason for this difficulty is the structural ambiguity that is common for conjunctive structures that appear in long sentences. Human beings can recognize conjunctive structures because of a certain, but sometimes subtle, similarity that exists between conjuncts. Therefore, we have developed an algorithm for calculating a similarity measure between two arbitrary series of words from the left and the right of a conjunction and selecting the two most similar series of words that can reasonably be considered as composing a conjunctive structure. This is realized using a dynamic programming technique. A long sentence can be reduced into a shorter form by recognizing conjunctive structures. Consequently, the total dependency structure of a sentence can be obtained by relatively simple head-dependent rules. A serious problem concerning conjunctive structures, besides the ambiguity of their scopes, is the ellipsis of some of their components. Through our dependency analysis process, we can find the ellipses and recover the omitted components. We report the results of analyzing 150 Japanese sentences to illustrate the effectiveness of this method.
Simulation driven resource allocation in ATM networks
Authors: Abdullah M. Alqaed, C. Hwa Chang
Venue: ACM SIGSIM Simulation Digest (1994)

Asynchronous Transfer Mode (ATM) traffic is characterized by a wide variety of traffic source classes. Each class of traffic has differing effects on the buffer and link capacity resources of the network. This results in a high level of complexity in predicting resource allocations for each source. The network must be managed in real-time in order to avoid congestion which tends to collapse its utilization. Network congestion requires admission control which in turn must require a measure of resource requirements from a randomly variable source. In this paper we proposed a frequency-domain probability density function convolution method for predicting the resource requirements of a source based on its input characteristics. A taxonomy and classification of sources based on measurable characteristics is also proposed. The classes of sources are simulated and the resulting requirements are compared to the prediction. A feedback mechanism is described which can result in a highly accurate and very efficient table lookup method for realtime resource allocation in ATM multiplexing switches.
Untying the Gordian knot: agreement in J
Authors: Martin Neitzel
Venue: Proceedings of the international conference on Applied programming languages (1995)

The &ldquo;Dictionary of J&rdquo; is not written for the faint of heart. Its numerous self-references make it very difficult to tackle. The author thinks that section II.B, &ldquo;Verbs&rdquo;, is one of the keys for getting a confident grip of the language. This paper basically just repeats this section using a tutorial style, some historical background, and several pictures. Hopefully, it will enable people with analytical minds to find their own way through the Dictionary. It closes with a discussion of possible language changes in the context of II.B
A worst case of circularity test algorithms for attribute grammars
Authors: Pei-Chi Wu, Feng-Jian Wang
Venue: ACM Transactions on Programming Languages and Systems (TOPLAS) (1995)

Although the circularity test problem for attribute grammars (AGs) has been proven to be intrinsically exponential, to date, a worst case for the existing circularity test algorithms has yet to be presented. This note presents a worst-case AG in which the number of incomparable dependency graphs induced at the root is exponential. The worst case can help to clarify the complexity of the problem.
An analytic study of dynamic hardware and software cache coherence strategies
Authors: Harjinder S. Sandhu, Kenneth C. Sevcik
Venue: Proceedings of the 1995 ACM SIGMETRICS joint international conference on Measurement and modeling of computer systems (1995)

Dynamic software cache coherence strategies use information about program sharing behaviour to manage caches at run-time and at a granularity defined by the application. The program-level information is obtained through annotations placed into the application by the user or the compiler. The coherence protocols may range from simple static algorithms to dynamic algorithms that use run-time data structures similar to the directories used in hardware strategies. In this paper, we present an analytic study of five dynamic software cache coherence algorithms and compare these to a representative hardware coherence strategy. The analytic model is constructed using four input parameters --- write probability, locality, granularity, and system size --- and solved by analysis of a Markov chain. We show that the fundamental tradeoffs between the different hardware and software strategies are captured in this model. The results of the study show that hardware schemes perform better for fine-grained data structures for much of the parameter space that we study. However, for coarse-grained data structures, various software algorithms are dominant over most of the parameter space. Further, hardware strategies are found to be more susceptible to the effects of contention, and also perform worse for the asymmetric workload that we study.
Approximate Analysis of Reader/Writer Queues
Authors: Theodore Johnson
Venue: IEEE Transactions on Software Engineering (1995)

We analyze the performance of queues that serve readers and writers. Readers are served concurrently, while writers require exclusive service. We approximately analyze a first-come-first-serve (FCFS) reader/writer queue, and derive simple formulae for computing waiting times and capacity under the assumption of Poisson arrivals and exponential service. We extend the analysis to handle a one-writer queue, and a queue that includes write-intention locks. The simple analyses that we present can be used as rules-of-thumb for designing concurrent systems.