ppxscal/embedding_network huggingface dataset:
Safe type checking in a statically-typed object-oriented programming language
Authors: Kim B. Bruce
Venue: Proceedings of the 20th ACM SIGPLAN-SIGACT symposium on Principles of programming languages (1993)

In this paper we introduce a statically-typed, functional, object-oriented programming language, TOOPL, which supports classes, objects, methods, instance variable, subtypes, and inheritance. It has proved to be surprisingly difficult to design statically-typed object-oriented languages which are nearly as expressive as Smalltalk and yet have no holes in their typing systems. A particular problem with statically type checking object-oriented languages is determining whether a method provided in a superclass will continue to type check when inherited in a subclass. This program is solved in our language by providing type checking rules which guarantee that a method which type checks as part of a class will type check correctly in all legal subclasses in which it is inherited. This feature enables library providers to provide only the interfaces of classes with executables and still allow users to safely create subclasses. The design of TOOPL has been guided by an analysis of the semantics of the language, which is given in terms of a sufficiently rich model of the F-bounded second-order lambda calculus. This semantics supported the language design by providing a means of proving that the type-checking rules for the language are sound, ensuring that well-typed terms produce objects of the appropriate type. In particular, in a well-typed program it is impossible to send a message to an object which lacks a corresponding method.
Evaluating the use of pre-simulation in VLSI circuit partitioning
Authors: Roger D. Chamberlain, Cheryl D. Henderson
Venue: Proceedings of the eighth workshop on Parallel and distributed simulation (1994)

One of the significant difficulties in partitioning logic circuits for distributed simulation is the lack of a priori knowledge concerning the evaluation frequency of individual circuit elements. A number of researchers have resorted to pre-simulation to estimate these evaluation frequencies. In this paper we empirically investigate the wisdom of relying on pre-simulation results, and evaluate the degree to which early evaluation frequencies predict later evaluation frequencies. The results show that, for simulations that use random input vectors, pre-simulation has clear merit in predicting circuit element evaluation frequency. This supports the use of pre-simulation as an input to circuit partitioning algorithms.
The transitive closure of control dependence: the iterated join
Authors: Michael Weiss
Venue: ACM Letters on Programming Languages and Systems (LOPLAS) (1992)

We characterize the transitive closure of the control dependence relation and give an application to the theory of control fow guards. We relate our result to characterizations by Beck et al., by Sarkar, and by Cytron et al., and strengthen a result of the latter concerning dominance frontiers and join sets.
Solution to complex queueing systems: a spreadsheet approach
Authors: Surendra M. Gupta, Fikri Karaesmen
Venue: ACM SIGMETRICS Performance Evaluation Review (1994)

In this paper, some very useful and applicable ideas are presented to facilitate solving complex problems in Queueing Theory. It is demonstrated how a spreadsheet can be used to solve problems which many practitioners find very intimidating. To this end an algorithm is presented which is particularly designed for easy implementation in a spreadsheet. A template is provided illustrating the implementation of the algorithm. The use of the template is demonstrated in various queueing applications.
Report of the 1993 workshop on rapid prototyping of microelectronic systems for universities
Authors: Phil Allen, Franc Brglez, Hal Carter, Robert Caverly, Jerry Dillion, Albert Lo, Ron Lomax, John Oldfield, Cesar Pina, T. J. Wilkinson
Venue: ACM SIGARCH Computer Architecture News (1994)

Under sponsorship of the National Science Foundation, eleven participants from universities and industry and seven individuals from the NSF met during October 18-19, 1993, to assess the unique needs educators have for rapid prototyping of microelectronic systems and to suggest potential solutions for continuously improving the state-of-the-art in U.S. universities. The following vision statement was adopted: Educate students who can use the paradigm of design, simulate, design-for-test, build and test (as opposed to just design, build and test) to create microelectronic systems, not just integrated circuits tiCs), of sufficient quality that the global competitiveness of U.S. industry will be continued and enhanced. From this statement a number of findings and recommendations were made. Some of these include: (1) Student projects should be simulated thoroughly prior to submission to MOSIS for fabrication. (2) The use of Field-Programmable Gate Arrays (FPGAs) to support logic design and systems-oriented courses should be encouraged. (3) Fabrication services provided by MOSIS should be used largely for designs in which some portion has been performed manually. (4) NSF support for advanced classes should be broadened to include not only IC fabrication via MOSIS but also the acquistion of prototyping boards or multi-chip modules (MCMs) (5) Remote access via the Internet to expensive testers and prototyping systems should be made available. (6) MOSIS should add the following services: BiCMOS process, microelectro-mechanical post-processing, optoelectronic device fabrication and MCM prototyping. (7) A national clearinghouse should be supported to provide ready access by the educational community to existing and rapidly emerging resources that are presently dispersed. (8) Conferences, faculty enhancement short courses and newsletters should be supported to encourage widespread exchange of information.
On Asymmetric Invalidation with Partial Tests
Authors: Vijay Raghavan
Venue: IEEE Transactions on Computers (1993)

R. Gupta and I.V. Ramakrishnan (1987) proposed a general model for fault diagnosis that uniformly handles intermittent faults, masking, and partial testing. In this model, the diagnosability problem is open if asymmetric invalidation is used, although a polynomial time algorithm was once incorrectly claimed. It is shown that the problem is really co-NP complete. An efficient diagnosis algorithm for this model is presented.
Original Contribution: Local conditions for phase transitions in neural networks with variable connection strengths
Authors: Frank E. McFadden, Yun Peng, James A. Reggia
Venue: Neural Networks (1993)

Qualitative changes in the behavior of a neural network may occur when parameters cross critical boundaries. These phase transitions may be triggered either by learning or by the intrinsic dynamics of the network, and must be understood in order to guarantee that the behavior of the model will be meaningful. This is particularly important for models with connection strengths that are permitted to vary rapidly. Such models, which have been applied to a variety of problems in computer science, neuroscience, and cognitive science, may display transitions from phases characterized by bounded total activation to phases during which total activation may grow explosively. It has been observed, however, that even when total network activation remains bounded, individual node activations can grow without limit. In this paper, local conditions for boundedness and divergence are derived, in the form of a balance between each node's decay vs the gain it imparts to the rest of the system. These conditions do not require that the connection matrix be symmetric. These results extend the range of models whose phase transitions are understood and, therefore, expand the choices of well-behaved models that may be selected for applications.
A polymorphic calculus for views and object sharing (extended abstract)
Authors: Atsushi Ohori, Keishi Tajima
Venue: Proceedings of the thirteenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems (1994)

We present a typed polymorphic calculus that supports a general mechanism for view definition and object sharing among classes. In this calculus, a class can contain inclusion specifications of objects from other classes. Each such specification consists of a predicate determining the subset of objects to be included and a viewing function under which those included objects are manipulated. Both predicates and viewing functions can be any type consistent programs definable in the polymorphic calculus. Inclusion specifications among classes can be cyclic, allowing mutually recursive class definitions. These features achieve flexible view definitions and wide range of class organizations in a compact and elegant way. Moreover, the calculus provides a suitable set of operations for views and classes so that the programmer can manipulate views and classes just the same way as one deals with ordinary records and sets.The proposed calculus uniformly integrates views and classes in a polymorphic type system of a database programming language similar to Machiavelli. The calculus has a type inference algorithm that relieves the programmer from complicated type declarations of views and classes. The polymorphic type system of the calculus is also shown to be sound, which guarantees complete static check of type consistency of programs involving classes and views. Through these properties, the programmer can enjoy full advantages of polymorphism and type inference when writing object-oriented database programs.
A technique for tracing memory leaks in C++
Authors: Steven J. Beaty
Venue: ACM SIGPLAN OOPS Messenger (1994)

Dynamic memory usage in C++ can lead to unrecovered allocations. A method of overloading the builtin new and delete functions is introduced that can ameliorate this problem.
Concurrent compacting garbage collection of a persistent heap
Authors: James O'Toole, Scott Nettles, David Gifford
Venue: ACM SIGOPS Operating Systems Review (1993)

We describe a replicating garbage collector for a persistent heap. The garbage collector cooperates with a transaction manager to provide safe and efficient transactional storage management. Clients read and write the heap in primary memory and can commit or abort their write operations. When write operations are committed they are preserved in stable storage and survive system failures. Clients can freely access the heap during garbage collection because the collector concurrently builds a compact replica of the heap. A log captures client write operations and is used to support both the transaction manager and the replicating garbage collector.Our implementation is the first to provide concurrent and compacting garbage collection of a persistent heap. Measurements show that concurrent replicating collection produces significantly shorter pause times than stop-and-copy collection. For small transactions, throughput is limited by the logging bandwidth of the underlying log manager. The results suggest that replicating garbage collection offers a flexible and efficient way to provide automatic storage management in transaction systems, object-oriented databases and persistent programming environments.
Determining the shortest process migration paths for program compilation using a dynamic programming approach
Authors: K. C. Wong
Venue: ACM SIGOPS Operating Systems Review (1993)

Programs written in multiple, partially disjoint versions of a high-level language may have to migrate for program compilation in the environment in which the versions are distributed. The decisions made during program compilation concerning which node is to be selected from the possible ones supporting those disjoint features constitute a process migration path. The shortest paths which minimize the time spent in process migration can be determined using a dynamic programming approach. The approach is versatile in that it determines some of the shortest paths in a branch-and-bound way and determines all of the shortest paths in a non-brute force way by pruning those branches at the turning points that version expansion is not necessary.
Management guidelines for PC security
Authors: Troy E. Anderson
Venue: ACM SIGICE Bulletin (1994)

In the last several years, the number of personal computers (PCs) in offices worldwide has skyrocketed. In fact, some businesses now have PC bases in the thousands, a fact which makes company security officers' jobs a nightmare. Much of the existing literature addresses security in general, or security in large mainframe environments. The goal of this paper is to present potential security problems for stand-alone and networked PCs, and to offer guidelines to prevent or avoid these threats to PC security.
Strictness optimization for graph reduction machines (why id might not be strict)
Authors: Marcel Beemster
Venue: ACM Transactions on Programming Languages and Systems (TOPLAS) (1994)

Strictness optimizations in the implementation of lazy functional languages are not always valid. In nonoptimized graph reduction, evaluation always takes place at the request of case analysis or a primitive operation. Hence, the result of a reduction is always a data value and never a function. This implies that in an implementation no argument satisfaction check is required. But in the presence of strict arguments, &ldquo;premature&rdquo; reduction may take place outside the scope of a case or primitive operation. This causes problems in graph reducers that use an aggressive take. Two solutions are presented, one based on a run-time argument satisfaction check, the other on a weakened strictness analyzer. Experimental results are used to compare the two solutions and show that the cost of the aggressive take can be arbitrarily high for specific programs. The experimental results enable a trade-off to be made by the reduction machine designer.
Model checking and abstraction
Authors: Edmund M. Clarke, Orna Grumberg, David E. Long
Venue: ACM Transactions on Programming Languages and Systems (TOPLAS) (1994)

We describe a method for using abstraction to reduce the complexity of temporal-logic model checking. Using techniques similar to those involved in abstract interpretation, we construct an abstract model of a program without ever examining the corresponding unabstracted model. We show how this abstract model can be used to verify properties of the original program. We have implemented a system based on these techniques, and we demonstrate their practicality using a number of examples, including a program representing a pipelined ALU circuit with over 101300 states.
&ldquo;Excellent&rdquo; systems analysts: key audience perceptions
Authors: M. Gordon Hunter
Venue: ACM SIGCPR Computer Personnel (1994)

Within the context of the desire to address the concerns of the software crisis, a research project was initiated to identify the skills and personal characteristics of "excellent" systems analysts. The project included 53 participants from 2 companies representing 5 groups or Audiences of individuals who interact with systems analysts. The data, gathered using Kelly's RepGrid technique, represent Audience perceptions of what constitutes an "excellent" systems analyst. Overall, the more important aspects, or Themes, which emerged from the data include communicate, attitude, knowledge, investigate, and experience. These common themes are referred to as "universals". The detailed interpretations of these aspects, as determined from the research data, varied amongst the Audiences and seem to reflect Audience objectives. For instance, User Audiences emphasized content related aspects, such as knowledge. Systems analyst and their supervisors, however, tended to differentiate on process related aspects, such as investigate. Each Audience and each corporation involved in this project had its own interpretation of the relative importance of what constitutes an "excellent" systems analyst. Thus, the importance of each "universal" has a "local" relative value.
Modeling Correlation in Software Recovery Blocks
Authors: Lorrie A. Tomek, Jogesh K. Muppala, Kishor S. Trivedi
Venue: IEEE Transactions on Software Engineering (1993)

The authors examine the problem of accurately modeling the software fault-tolerance technique based on recovery blocks. Analysis of some systems have investigated the correlation between software modules, which may be due to a portion of the functional specification that is common to all software modules, or to the inherent hardness of some problems. Three types of dependence which can be captured using measurements are considered. These are correlation between software modules for a single input, correlation between successive acceptance tests on correct module outputs and incorrect module outputs, and correlation between subsequent inputs. The authors' technique is quite general and can be applied to other types of correlation. In accounting for dependence, they use the intensity distribution introduced by D.E. Eckhardt and L.D. Lee (1985). A method of generating the intensity distribution that is based on the pairwise correlation between modules is discussed. This method is contrasted with the assumption of independent modules as well as the use of the beta-binomial density introduced by V.F. Nicola and A. Goyai (1990). The effects of dependencies were studied using a Stochastic Reward Network (SRN) that incorporates all of the above dependencies and a modeling tool called Stochastic Petri Net Package (SPNP).
An optimal algorithm for the (&le; k)-levels, with applications to separation and transversal problems
Authors: Hazel Everett, Jean-Marc Robert, Marc van Kreveld
Venue: Proceedings of the ninth annual symposium on Computational geometry (1993)

This paper gives an optimal Onlogn+nk time algorithm for constructing the levels 1,&hellip;,k in an arrangement of n lines in the plane. This algorithm is extended to compute these levels in an arrangement of n unbounded x-monotone polygonal convex chains, of which each pair intersects at most a constant number of times. These algorithms can be used to solve the following separation and transversal problems. For a set n blue points and an set of n red points, find a line that separates the two sets in such a way that the sum, m, of the number of red points above the line and the number of blue points below the line is minimized. Such an optimal line can be found in Onmlogm+nlogn time. For a set of nline segments in the plane, find a line that intersects the maximum number of the line segments. Such an optimal line can be found in Onmlogm+nlogn time for vertical segments and in Onmlogm+nlog 2nan expected time for arbitrary line segments, where m denotes the number of line segments not intersected by the optimal line.
Change at ONR, and many funding announcements elsewhere
Authors: Marianne Winslett
Venue: ACM SIGMOD Record (1993)

In this issue, we describe recent changes at the US Office of Naval Research, and then cover a dozen recent announcements of funding in the US for postdocs, sabbaticals, summer jobs, equipment, and research grants&mdash;just about anything you might need&mdash;from DARPA, the Army, the Air Force, NSF, NIST, and the National Center for Automated Information Research. We also list the newly funded NSF Grand Challenge proposals.
The role of stakeholders' expectations in predicting information systems implementation outcomes
Authors: Aline F. de Abreu, David W. Conrath
Venue: Proceedings of the 1993 conference on Computer personnel research (1993)

An integrative model of IS implementation success is presented. The model focuses on stakeholders' expectations as predictors of IS implementation outcomes, and on the organization's competence in designing and implementing the system. The proposed framework is derived from the literature on IS implementation, especially those studies that explain and/or predict the outcomes of such a process. The framework attempts to integrate the existing research streams: factor studies, process studies and expectancy studies. The model uses a multiperspective approach by taking into consideration stakeholders' different views of these processes.
Education is the future of APL
Authors: Howard A. Peelle, Alexandr Skomorokhov
Venue: ACM SIGAPL APL Quote Quad (1993)

A critical challenge confronts the APL community: How to ensure a positive future for APL. While problems persist and effective actions remain to be taken, solutions can be found in education.Besides APL's acknowledged strengths and potential for growth (well-known to this audience), various deterrents are reviewed. Important educational issues are identified, and a summary report is given of the "APL in Education" workshop (held during APL92) where issues were discussed, goals clarified, strategies proposed, and action plans generated. The APL community is charged with carrying out the plans and disseminating results both internally (via APL Quote Quad, Vector, APL News, etc.) as well as internationally to prospective APL users.
Probabilistic Bounds on the Extremal Eigenvalues and Condition Number by the Lanczos Algorithm
Authors: J. Kuczynski, H. Wozniakowski
Venue: SIAM Journal on Matrix Analysis and Applications (1994)

The authors analyze the Lanczos algorithm with a random start for approximating the extremal eigenvalues of a symmetric positive definite matrix. They present some bounds on the Lebesgue measure (probability) of the sets of these starting vectors for which the Lanczos algorithm gives at the $k$th step satisfactory approximations to the largest and smallest eigenvalues. Combining these bounds gets similar estimates for the condition number of a matrix.
Alternating-Sign Matrices and Domino Tilings (Part II)
Authors: Noam Elkies, Greg Kuperberg, Michael Larsen, James Propp
Venue: Journal of Algebraic Combinatorics: An International Journal (1992)

We continue the study of the family of planar regions dubbed Aztec diamonds in our earlier article and study the ways in which these regions can be tiled by dominoes. Two more proofs of the main formula are given. The first uses the representation theory of GL(n). The second is more combinatorial and produces a generating function that gives not only the number of domino tilings of the Aztec diamond of order n but also information about the orientation of the dominoes (vertical versus horizontal) and the accessibility of one tiling from another by means of local modifications. Lastly, we explore a connection between the combinatorial objects studied in this paper and the square-ice model studied by Lieb.