ppxscal/embedding_network huggingface dataset:
The Performance of Parity Placements in Disk Arrays
Authors: Edward K. Lee, Randy H. Katz
Venue: IEEE Transactions on Computers (1993)

Due to recent advances in central processing unit (CPU) and memory system performance, input/output (I/O) systems are increasingly limiting the performance of modern computer systems. Redundant arrays of inexpensive disks (RAID) have been proposed to meet the impending I/O crisis. RAIDs substitute many small inexpensive disks for a few large expensive disks to provide higher performance, smaller footprints, and lower power consumption at a lower cost than the large expensive disks they replace. RAIDs provide high availability by using parity encoding of data to survive disk failures. It is shown that the way parity is distributed in a RAID has significant consequences for performance. The performances of eight different parity placements are investigated using simulation.
Authentication in the Taos operating system
Authors: Edward Wobber, Martín Abadi, Michael Burrows, Butler Lampson
Venue: ACM SIGOPS Operating Systems Review (1993)

We describe a design and implementation of security for a distributed system. In our system, applications access security services through a narrow interface. This interface provides a notion of identity that includes simple principals, groups, roles, and delegations. A new operating system component manages principals, credentials, and secure channels. It checks credentials according to the formal rules of a logic of authentication. Our implementation is efficient enough to support a substantial user community.
Towards tractable algebras for bags
Authors: Stéphane Grumbach, Tova Milo
Venue: Proceedings of the twelfth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems (1993)

Bags, i.e. sets with duplicates, are often used to implement relations in database systems. In this paper we study the expressive power of algebras for manipulating bags. The algebra we present is a simple extension of the nested relation algebra. Our aim is to investigate how the use of bags in the language extends its expressive power, and increases its complexity. We consider two main issues, namely (i) the relationship between the depth of bag nesting and the expressive power, and (ii) the relationship between the algebraic operations, and their complexity and expressive power. We show that the bag algebra is more expressive than the nested relation algebra (at all levels of nesting), and that the difference may be subtle. We establish a hierarchy based on the structure of algebra expressions. This hierarchy is shown to be highly related to the properties of the powerset operator.
An alternating fixpoint tailored to magic programs
Authors: Shinichi Morishita
Venue: Proceedings of the twelfth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems (1993)

We study applying the magic-sets transformation technique to Datalog programs with negation that may not have 2-valued well-founded models. In this general setting we encounter the problem that the well-founded model of the original program does not always agree with the well-founded model of the magic program derived by commonly used left-to-right sips on the query. In order to fix this disagreement we present a novel method that is obtained by slightly and naturally tailoring Van Gelder's alternating fixpoint technique [16] to a magic program.
On the power of algebras with recursion
Authors: Catriel Beeri, Tova Milo
Venue: Proceedings of the 1993 ACM SIGMOD international conference on Management of data (1993)

We consider the relationship between the deductive and the functional/algebraic query language paradigms. Previous works considered this subject for a non-recursive algebra, or an algebra with a fixed point operation, and the corresponding class of deductive queries is that defined by stratified programs. We consider here algebraic languages extended by general recursive definitions. We also consider languages that allow non-restricted use of negation. It turns out that recursion and negation in the algebraic paradigm need to be studied together. The semantics used for the comparison is the valid semantics, although other well-known declarative semantics can also be used to derive similar results. We show that the class of queries expressed by general deduction with negation can be captured using algebra with recursive definitions.
Wait-Free Consensus Using Asynchronous Hardware
Authors: Benny Chor, Amos Israeli, Ming Li
Venue: SIAM Journal on Computing (1994)

This paper studies the wait-free consensus problem in the asynchronous shared memory model. In this model, processors communicate by shared registers that allow atomic read and write operations (but do not support atomic test-and-set). It is known that the wait-free consensus problem cannot be solved by deterministic protocols. A randomized solution is presented. This protocol is simple, constructive, tolerates up to $n-1$ processors crashes (where $n$ is the number of processors), and its expected run-time is $O(n^2)$.
NetCash: a design for practical electronic currency on the Internet
Authors: Gennady Medvinsky, Clifford Neuman
Venue: Proceedings of the 1st ACM conference on Computer and communications security (1993)

Licensing is a topic of increasing importance for software publishers and users. More and more, the magnitude of financial transfers between these two partners are determined by some electronic licensing service being part of the system on which the licensed software is running. In order to ease the use and management of such licensing schemes and to enable economic software usage in enterprise-wide computer systems through flexible and fair billing structures, various organizations are working on formulating requirements, defining architectures, and building standard interfaces for so called license brokerage systems. The trustworthiness of these services is essential because large amounts of money can depend on them. Most of these licensing services are currently operating independently of access control and rely on proprietary and unpublished security algorithms. This paper proposes an extension of access control to integrate licensing called Stateful Access Control and it addresses some aspects of virus protection.
For neural networks, function determines form
Authors: Francesca Albertini, Eduardo D. Sontag
Venue: Neural Networks (1993)

This article shows that the weights of continuous-time feedback neural networks are uniquely identifiable from input/output measurements. Under weak genericky assumptions, the following is true: Assume given two nets, whose neurons all have the same nonlinear activation function a; if the two nets have equal behaviors as ''black boxes'' then necessarily they must have the same number of neurons and-except at most for sign reversals at each node-the same weights. Moreover, even if the activations are not a priori known to coincide, they are shown to be also essentially determined from the external measurements.
Time Warp simulation in time constrained systems
Authors: Kaushik Ghosh, Richard M. Fujimoto, Karsten Schwan
Venue: ACM SIGSIM Simulation Digest (1993)

The suitability of the Time Warp mechanism to perform simulations with real-time constraints is examined. A model for Time Warp is developed that accounts for overheads such as state saving, state restoration, and sending and transmitting positive and negative messages. A criterion called R-schedulability is defined to indicate whether or not computations can meet real-time deadlines. It is shown that if false events (events that will be rolled back or cancelled later) are generated, and there are no committed events with timestamps equal to those of the false events, Time Warp cannot meet the R-schedulability criterion. Further, if aggressive cancellation is used, scheduling guarantees still cannot be made even in the absence of such false events. However, Time Warp using lazy cancellation is shown to be R-schedulable provided such false events do not exist. Finally, based on these results, bounds on the execution time of a Time Warp simulation are derived.
Uniprep&mdash;preparing a C/C++ compiler for Unicode
Authors: Martin J. Dürst
Venue: ACM SIGPLAN Notices (1994)

A new way to ease the transition of programs and programmers to multilingual 16-bit character sets is presented. A filter, called uniprep, is inserted between the C/C++ macro preprocessor and the compiler itself. It substitutes wide-character constants and strings by appropriately converted and casted traditional constants.
Semantic data modeling of hypermedia associations
Authors: John L. Schnase, John J. Leggett, David L. Hicks, Ron L. Szabo
Venue: ACM Transactions on Information Systems (TOIS) (1993)

Many important issues in the design and implementation of hypermedia system functionality focus on the way interobject connections are represented, manipulated, and stored. A prototypic system called HB1 is being designed to meet the storage needs of next-generation hypermedia system architectures. HB1 is referred to as a hyperbase management system (HBMS) because it supports, not only the storage and manipulation of information, but the storage and manipulation of the connectivity data that link information together to form hypermedia. Among HB1's distinctions is its use of a semantic network database system to manage physical storage. Here, basic semantic modeling concepts as they apply to hypermedia systems are reviewed, and experiences using a semantic database system in HB1 are discussed. Semantic data models attempt to provide more powerful mechanisms for structuring objects than are provided by traditional approaches. In HB1, it was necessary to abstract interobject connectivity, behaviors, and information for hypermedia. Building on top of a semantic database system facilitated such a separation and made the structural aspects of hypermedia conveniently accessible to manipulation. This becomes particularly important in the implementation of structure-related operations such as structural queries. Our experience suggests that an integrated semantic object-oriented database paradigm appears to be superior to purely relational, semantic, or object-oriented methodologies for representing the structurally complex interrelationships that arise in hypermedia.
Context-based synchronization: an approach beyond semantics for concurrency control
Authors: Man H. Wong, Divyakant Agrawal
Venue: Proceedings of the twelfth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems (1993)

The expressiveness of various object-oriented languages is investigated with respect to their ability to create new objects. We focus on database method schemas (dms), a model capturing the data manipulation capabilities of a large class of deterministic methods in object-oriented databases. The results clarify the impact of various language constructs on object creation. Several new constructs based on expanded notions of deep equality are introduced. In particular, we provide a tractable construct which yields a language complete with respect to object creation. The new construct is also relevant to query complexity. For example, it allows expressing in polynomial time some queries, like counting, requiring exponential space in dms alone.
A dynamic processor allocation policy for multiprogrammed shared-memory multiprocessors
Authors: Cathy McCann, Raj Vaswani, John Zahorjan
Venue: ACM Transactions on Computer Systems (TOCS) (1993)

We propose and evaluate empirically the performance of a dynamic processor-scheduling policy for multiprogrammed shared-memory multiprocessors. The policy is dynamic in that it reallocates processors from one parallel job to another based on the currently realized parallelism of those jobs. The policy is suitable for implementation in production systems in that: &mdash;It interacts well with very efficient user-level thread packages, leaving to them many low-level thread operations that do not require kernel intervention. &mdash;It deals with thread blocking due to user I/O and page faults. &mdash;It ensures fairness in delivering resources to jobs. &mdash;Its performance, measured in terms of average job response time, is superior to that of previously proposed schedulers, including those implemented in existing systems. It provides good performance to very short, sequential (e.g., interactive) requests. We have evaluated our scheduler and compared it to alternatives using a set of prototype implementations running on a Sequent Symmetry multiprocessor. Using a number of parallel applications with distinct qualitative behaviors, we have both evaluated the policies according to the major criterion of overall performance and examined a number of more general policy issues, including the advantage of &ldquo;space sharing&rdquo; over &ldquo;time sharing&rdquo; the processors of a multiprocessor, and the importance of cooperation between the kernel and the application in reallocating processors between jobs. We have also compared the policies according to other criteia important in real implementations, in particular, fairness and respone time to short, sequential requests. We conclude that a combination of performance and implementation considerations makes a compelling case for our dynamic scheduling policy.
Commercial products for CSCW: a panel report from CSCW'92
Authors: Kristina A. Lindholm
Venue: ACM SIGCHI Bulletin (1993)

If we had to pick one phrase to sum up the discussion that took place at the CSCW commercial products panel it would be "change takes time" --- change not only in technology but also in the way people behave. All of the panelists remarked that the nature of CSCW products requires change --- in technology, in how people work and in how people think. All of this requires time. We have to be realistic when assessing how long it takes for CSCW products to catch on in the commercial market. Change is happening, it is just happening slowly and on many different levels.
Computer-based systems: a discussion of their application to managerial decision-support
Authors: Francis A. Wilson, John N. Wilson, Anne M. Smith
Venue: Proceedings of the 1993 conference on Computer personnel research (1993)

Much of the current work into developing computer-based systems (CBS) as aids for managerial decision-making within organizations, still explains system failures as a psychological or organizational problem, i.e. a problem of inadequate &ldquo;acceptance&rdquo; of the CBS by the intended user. From this, the conclusion is drawn that &ldquo;more&rdquo; behavioural science research on user psychology can save the CBS-managerial decision-support concept. However, the underlying design ideal of CBS and the assumption of rational decision-making within organizations remains unquestioned. Any moves to question this ideal generally rest upon the issues of tool design in terms of providing alternative modes of information presentation in response to psychological &ldquo;user types&rdquo; and problem categories. This paper questions the ideals of rational managerial decision-making and the resulting paradigm of computer system support. It suggests that for effective support, the normative content (the political and moral foundations) of system design must be subject to critical appraisal to secure social rationality for use of CBS within organizational activities.
Using a Prolog meta-programming approach for a blackboard application
Authors: David G. Schwartz, Leon S. Sterling
Venue: ACM SIGAPP Applied Computing Review (1993)

Substantial integration and control issues arise when developing distributed, heterogeneous blackboard-based systems. We present the design and implementation of a Prolog-based blackboard system for the simulation of portfolio management tasks. The design addresses control and integration issues with an approach based on meta-level architectures and logic problems. A common interface capturing important meta-level knowledge about individual knowledge sources, i.e. the blackboard system components, is described. The interface is structured and can easily accomodate existing knowledge sources. Adaptive control is achieved by a set of control knowledge sources acting at both the object and meta levels. The goal of the application is to provide an environment in which independently developed subsystems used by a portfolio manager can be integrated and controlled without necessitating major modifications to the original code.
Providing end-to-end statistical performance guarantees with bounding interval dependent stochastic models
Authors: Hui Zhang, Edward W. Knightly
Venue: ACM SIGMETRICS Performance Evaluation Review (1994)

This paper demonstrates a new, efficient, and general approach for providing end-to-end performance guarantees in integrated services networks. This is achieved by modeling a traffic source with a family of bounding interval-dependent (BIND) random variables and by using a rate-controlled service discipline inside the network. The traffic model stochastically bounds the number of bits sent over time intervals of different length. The model captures different source behavior over different time scales by making the bounding distribution an explicit function of the interval length. The service discipline, RCSP, has the priority queueing mechanisms necessary to provide performance guarantees in integrated services networks. In addition, RCSP provides the means for efficiently extending the results from a single switch to a network of arbitrary topology. These techniques are derived analytically and then demonstrated with numerical examples.
Functional specification of time-sensitive communicating systems
Authors: Manfred Broy
Venue: ACM Transactions on Software Engineering and Methodology (TOSEM) (1993)

A formal model and a logical framework for the functional specification of time-sensitive communicating systems and their interacting components are outlined. The specification method is modular with respect to sequential composition, parallel composition, and communication feedback. Nondeterminism is included by underspecification. The application of the specification method to timed communicating functions is demonstrated. Abstractions from time are studied. In particular, a rational is given for the chosen concepts of the functional specification technique. The relationship between system models based on nondeterminism and system models based on explicit time notions is investigated. Forms of reasoning are considered. The alternating bit protocol is used as a running example.
High-speed switch scheduling for local-area networks
Authors: Thomas E. Anderson, Susan S. Owicki, James B. Saxe, Charles P. Thacker
Venue: ACM Transactions on Computer Systems (TOCS) (1993)

Current technology trends make it possible to build communication networks that can support high-performance distributed computing. This paper describes issues in the design of a prototype switch for an arbitrary topology point-to-point network with link speeds of up to 1 Gbit/s. The switch deals in fixed-length ATM-style cells, which it can process at a rate of 37 million cells per second. It provides high bandwidth and low latency for datagram traffic. In addition, it supports real-time traffic by providing bandwidth reservations with guaranteed latency bounds. The key to the switch's operation is a technique called parallel iterative matching, which can quickly identify a set of conflict-free cells for transmission in a time slot. Bandwidth reservations are accommodated in the switch by building a fixed schedule for transporting cells from reserved flows across the switch; parallel iterative matching can fill unused slots with datagram traffic. Finally, we note that parallel iterative matching may not allocate bandwidth fairly among flows of datagram traffic. We describe a technique called statistical matching, which can be used to ensure fairness at the switch and to support applications with rapidly changing needs for guaranteed bandwidth.
The OO software development process (abstract)
Authors: Dennis de Champeaux
Venue: ACM SIGPLAN OOPS Messenger (1993)

A 92 Vancouver, British Columbia, Canada 5 - 10 October 1992 Addendum to the Proceedings Panel Report- The 00 Software Development Process Report by: Dennis de Champeaux HP-Labs Members of the panel Dermis de Champeaux, HP-Lab, moderator Bob Balzer, Information Sciences Institute Dave Bulman, Pragmatics Kathleen Culver-Lozo, AT T Bell Laboratories Ivar Jacobson, Objectory Stephen J. Mellor, Project Technology Pankaj Garg, HP-Lab, co-organizer of the panel Aim of the panel Improving development processes is a key issue for the software community in general. The literature gives us some guidance with respect to major activities of the development process. The waterfall, spiral and fountain model all agree upon distinctions such as: requirements capture, analysis, design, implementation, testing, maintenance. They also agree in that they do not provide a finer granularity of the inside activities of analysis and design. We postulate that this omission is a key inhibitor to a more widespread acceptance of the 00 paradigm by project managers. They do not know how to plan a non-trivial 00 software development project. The purpose of this panel was to take the first steps towards developing such process models. More 5-10 October 1992 -61- specifically the panelists have been asked to address the following questions (among others): . Can you envision a generic OOA/ OOD development process? If so what are the major steps and deliverables of these steps. If not, why not? l If a software development organization had to choose between either doing a paradigm shift to 00, or improving its rating on the SE1 maturity scale what would you recommend? What are the relationships between the two? Qualify, if necessary, the answer with respect to an extant maturity level. It turned out that these, and the other questions, were quite hard for the panellists. Hence, we envision a follow on panel in the future where these topics will be raised again. In addition to this panel, I organized in 1992, workshops on 00 process: one at ECOOP and one also at OOPSLA. All the events had in common that the presenterslpanelists had hardly anything to say about process. The most tangible contributions were modest extensions of the standard macro process: requirements capture, analysis, design, implementation, test, maintenance, enhanced, of course, by the recommendation to iterate. Addendum to the Proceedings Hence, although the panel had lively exchanges, I refrain from giving the details because I do not feel that the state of the art was advanced. Instead I would like to point the reader to a report that proposes some details on the 00 analysis and design process: Dennis de Champeaux, Towards an 00 SW Development Process, HP-Labs Tech Report HPL-92-149, November 1992. [The contributors Doug Lea, Penelope Faure, and Mohammed Fayad could not be listed as authors for legal reasons.] For a copy contact: HP-Labs/ Technical Publications Dept./ 1501 Page Mill Rd Palo Alto, CA 94304 (415) 857 4573 OOPSLA92 -62 - Vancouver, British Columbia
Perturbation Analysis of a Condition Number for Linear Systems
Authors: Zhi-Quan Luo, Paul Tseng
Venue: SIAM Journal on Matrix Analysis and Applications (1994)

In 1952, A. J. Hoffman [J. Res. Natl. Bur. Standards, 49 (1952), pp. 263-2651] published a bound on the distance from any point to the solution set of a linear system. This bound subsequently has found applications in the sensitivity analysis of linear/integer programs and the convergence analysis of descent methods for linearly constrained minimization. A certain constant in Hoffman's bound may be interpreted as a condition number for the linear system and, in this paper, the authors give simple necessary and sufficient conditions for the constant to be uniformly bounded under perturbations on the problem data. Also, these conditions are related to a uniform boundedness condition on the vertex solutions proposed by J.-S. Pang.