ppxscal/embedding_network huggingface dataset:
Software Measurement and Formal Methods: A Case Study Centered on TRIO+ Specifications
Authors: Lionel C. Briand, Sandro Morasca
Venue: Proceedings of the 1st International Conference on Formal Engineering Methods (1997)

This paper presents a case study where product measures are defined for a formal specification language (TRIO+) and are validated as quality indicators. To this end, defect and effort data were collected during the development of a monitoring/control system for a power plant. We show that some of the underlying hypotheses of these measures are supported by empirical results and that several measures are significant early indicators of specification change and effort. From a more general perspective, this study exemplifies one important advantage of formal specifications: they are measurable and can thus be better controlled, assessed, and managed than informal ones.
Complexity of Workforce Scheduling in Transfer Lines
Authors: George L. Vairaktarakis, Xiaoqiang Cai
Venue: Journal of Global Optimization (2003)

Consider a production system that consists of m assembly stations arranged in series. All jobs enter the assembly line at station 1 and proceed with subsequent stations in the same order as in a flow shop. Each job spends a fixed amount of time c in each station, known as the production cycle. This production system is synchronous or paced because jobs move one station forward synchronously, every c time units. To ensure that all required work is performed in precisely c periods, the appropriate number of workers is assumed to be known for every task in each station. Hence, each job is specified by an m-tuple of workforce requirements. We are interested in ``level'' workforce schedules where workforce size fluctuations are minimal during the production horizon. In this article we define level workforce scheduling objectives and analyze the complexity status of the associated problems. We find that most of these problems are NP-complete even when m=2.
Python reference manual
Authors: Guido Rossum
Venue:  (1995)

Python is a simple, yet powerful, interpreted programming language that bridges the gap between C and shell programming, and is thus ideally suited for ``throw-away programming'''' and rapid prototyping. Its syntax is put together from constructs borrowed from a variety of other languages; most prominent are influences from ABC, C, Modula-3 and Icon. The Python interpreter is easily extended with new functions and data types implemented in C. Python is also suitable as an extension language for highly customizable C applications such as editors or window managers. Python is available for various operating systems, amongst which several flavors of UNIX (including Linux), the Apple Macintosh O.S., MS-DOS, MS-Windows 3.1, Windows NT, and OS/2. This reference manual describes the syntax and ``core semantics'''' of the language. It is terse, but attempts to be exact and complete. The semantics of non-essential built-in object types and of the built-in functions and modules are described in the Python Library Reference. For an informal introduction to the language, see the Python Tutorial.
A General Purpose Virtual Collaboration Room
Authors: Runhe Huang, Jianhua Ma
Venue: Proceedings of the 5th International Conference on Engineering of Complex Computer Systems (1999)

The general purpose virtual collaboration room (VCR) is an Internet based desktop groupware system that enables a group of remote individuals to flexibly and naturally conduct their collaborative teaching/learning/working without constraints on collaboration types, working styles, group scales, and system platforms. To cope with the complexity, a room metaphor, i.e., emulating a physical room and objects in it, is used as a framework of the system. System implementation becomes no more complex than the case of using one object by identifying associated objects in communication messages between a room server and clients. The VCR provides rich and effective support of awareness of the user, object, space, and their mutual relations. With the use of Java applets for system implementations, users can enter and use a VCR from any standard Java enabled Web browser.
A progress report on the Desperanto research project: software support for distributed processing
Authors: Sandra A. Mamrak, Dennis Leinbaugh, Toby S. Berk
Venue: ACM SIGOPS Operating Systems Review (1983)

The Desperanto research project has been investigating topics in the area of distributed computing systems since the Fall of 1980. The project addresses problems that arise in the design and implementation of software support for general-purpose resource sharing in networks consisting of heterogeneous nodes. Thus it is most closely related to the prototype RSEXEC system [19], the National Software Works project [2], Rochester's Intelligent Gateway [8] and the Livermore Network Communications system [21]. It is influenced less directly by other contemporary systems which address distributed computing and operating system issues in different contexts such as special-purpose distributed applications, homogeneous architectures or shared memory environments [1] [3] [4] [6] [7] [16] [17] [18] [23].Some results have been published to date [9] [10] [11] [12], and other results are currently in the review process [13]. Although it is still premature to publish the details of the solutions to the design problems in journal (or archival) form, this report has been prepared to describe design issues and progress made to date. This is intended as an informal status report for a wide readership.
A Speedup Comparative Study: Three Third Generation DSM Systems
Authors: Mario Donato Marino, Geraldo Lino de Campos
Venue: Proceedings of the Seventh International Conference on Parallel and Distributed Systems: Workshops (2000)

Nautilus is a Multi-threaded Distributed Shared Memory system based on scope consistency. The multithread implementation disallows the use of SIGIO signals and to minimize the context switch of traditional processes. This paper shows the speedups of some benchmarks submitted to Nautilus, being it compared with two other DSMs: TreadMarks and JIAJIA. This speedup comparison includes some benchmarks evaluation for different input sizes for each of them and a study of how the speedup behavior changes by increasing the input sizes. The benchmarks evaluated in this study are: LU (kernel from SPLASH II), Matmul (matrix multiplication) and SOR (from Rice University).
Multimedia synchronization for live presentation using the N-buffer approach
Authors: Chung-Ming Huang, Ruey-Yang Lee
Venue: Proceedings of the 1995 International Conference on Network Protocols (1995)

The demand of bringing multimedia information systems into distributed environments makes multimedia synchronization more difficult. In order to eliminate the side effects which result from delay jitters, we propose a bounded buffer allocation scheme, in which the audio stream adopts the blocking synchronization scheme and the video stream adopts the non-blocking synchronization scheme, for live audio and video presentations in this paper. The forward synchronization schemes are performed to overcome the asynchrony anomalies. Once some anomalies of presentations are detected, a forward re-synchronization scheme is triggered to eliminate the asynchrony anomalies. Neither a global clock nor a feedback mechanism is needed using the proposed method. Based on the proposed method, trade-offs between the presentation qualities and networking resources are mathematically calculated. According to these calculable trade-offs, users can derive their own (acceptable) presentation qualities of live video and live audio media based on their available networking resources
A Method for Solving Certain Graph Recognition and Optimization Problems, with Applications to Perfect Graphs
Authors: Sue H. Whitesides
Venue:  (1982)

A polynomial time membership test and solutions to the minimum coloring and maximum weight clique and stable set problems are given for certain families of graphs. In particular, it is shown that for any arbitrary hereditary family of graphs, these problems can be solved quickly for the entire family whenever they can be solved quickly for the clique cutset free members of the family. If the graphs in the family are perfect, then a similar statement holds for the mimimum weight clique and stable set problems. These results are obtained by applying a polynomial time algorithm for determining whether a graph has a clique cutset. Several questions of Gavril concerning ``clique separable'''' perfect graphs are answered, and a polynomial time recognition algorithm for Gallai''s ``i-triangulated'''' perfect graphs is given. Keywords: graph algorithms, cliques, stable sets, perfect graphs, clique separable graphs, i-triangulated graphs.
Efficient Compositing Methods for the Sort-Last-Sparse Parallel Volume Rendering System on Distributed Memory Multicomputers
Authors: Don-Lin Yang, Jen-Chih Yu, Yeh-Ching Chung
Venue: Proceedings of the 1999 International Conference on Parallel Processing (1999)

In the sort-last-sparse parallel volume rendering system on distributed memory multi-computers, as the number of processors increases, in the rendering phase, we can get a good speedup because each processor renders images locally without communicating with other processors. However, in the compositing phase, a processor has to exchange local images with other processors. When the number of processors is over a threshold, the image compositing time becomes a bottleneck. In this paper, we proposed three compositing methods, the binary-swap with bounding rectangle method, the binary-swap with run-length encoding and static load-balancing method, and the binary-swap with bounding rectangle and run-length encoding method, to efficiently reduce the compositing time in the sort-last-sparse parallel volume rendering system on distributed memory multi-computers. The proposed methods were implemented on an SP2 parallel machine along with the binary-swap compositing method. The experimental results show that the binary-swap with bounding rectangle and run-length encoding method has the best performance among the four methods.
Towards a WAM Model for Lambda Prolog
Authors: Gopalan Nadathur, Bharat Jayaraman
Venue:  (1989)

Issues concerning the implementation of the logic programming language $\lambda$Prolog are investigated. This language extends Prolog by providing for higher-order notions and incorporating a richer set of search primitives. Techniques must therefore be devised for implementing these two new aspects. Extensions to the Warren Abstract Machine (WAM) are proposed in order to deal with the several significant new problems that arise in conjunction with the former aspect. A representation for $\lambda$-terms is outlined that facilitates the examination of their internal structure while simultaneously permitting reductions to be performed easily. Mechanisms are discussed for implementing higher-order unification - an operation that is much more complex than first-order unification - within the backtracking paradigm of Prolog. Instructions for creating $\lambda$-terms and invoking operations within unification are also provided. The nature of compiled code is illustrated through examples, and it is argued that the enhancements to the WAM preserve its behavior over first-order programs. The ideas presented in this paper are the basis of an implementation effort that is currently underway.
How to Encrypt /usr/dict/words in About a Second
Authors: Peter Su, Matt Bishop
Venue:  (1992)

We present an implementation of the Data Encryption Standard on the Connection Machine architecture. The DES encryption algorithm is ideally suited to the Connection Machine because it consists of bit serial operations, and thousands of encryptions can be done in parallel, independently of one another. Thus, our code encrypts passwords about ten times faster than the fastest competition that we know about. In addition, the nature of the Connection Machine''s architecture is such that some of the optimizations that make DES run much faster on conventional architectures have no effect on the performance of the Connection Machine. Our comparison of a simple implementation along with one that uses many optimizations illustrates this fact.
Hierarchical, Adaptive Cache Consistency in a Page Server OODBMS
Authors: Markos Zaharioudakis, Michael J. Carey
Venue: Proceedings of the 17th International Conference on Distributed Computing Systems (ICDCS '97) (1997)

Due to its simplicity and communication efficiency, many client-server object-oriented database systems are based on the basic page server architecture -- pages serve as their smallest unit of data transfer, client caching, and concurrency control. In an earlier paper, we showed how to extend this architecture to permit object-level callback locking, and we showed through simulations that significant performance gains can be expected. In the current paper, we report on our experiences from implementing this approach in the context of the SHORE system, which supports a generalized peer-servers architecture. In addition to discussing some of the stickier implementation details, we also explain how our callback algorithm was extended to support the hierarchical locking approach used in SHORE. Finally, we present performance measurements obtained by running SHORE on an IBM SP2 machine.
The token-bank leaky bucket mechanism for group connections in ATM networks
Authors: Sheng-Lin Wu, W.-S. E. Chen
Venue: Proceedings of the 1996 International Conference on Network Protocols (ICNP '96) (1996)

A well accepted policing mechanism for ATM networks is the leaky bucket mechanism. The original leaky bucket has been shown to be effective for traffic with a constant bit rate, but reacts poorly to bursty traffic. Although there are some other policing mechanisms in the literature that provide improvements over the original leaky bucket, most of them enforce the negotiated parameters for individual source traffic and do not fully utilize the statistical multiplexing of multiple connections. As a result, the bandwidth utilisation is low. Even though some source policing mechanisms have been proposed for group connections, they either fail to explore statistical multiplexing fully or do not provide a scheme to protect well-behaved sources from malicious ones in the group. We propose a new source policing mechanism, called the token-bank leaky bucket, for group connections in ATM networks. The mechanism explores the statistical multiplexing of multiple connections in the group and allows the unused bandwidth to be effectively shared by the connections that need it. In addition, it sets a limit of excessive data cells a source can send in a cycle in order to protect well-behaved sources against malicious sources. It is shown by simulations to have a lower violation probability and better bandwidth utilization even for small group connections when compared to the original leaky bucket with a similar configuration.
Linear representation of Buekenhout--Metz unitals
Authors: Olga Polverino
Venue: Discrete Mathematics (2003)

In the linear representation of the desarguesian plane PG(2,q2) in PG(5,q), the classical unital (the hermitian curve) is represented by an elliptic quadric ruled by lines of a normal spread. In this paper, we prove that a Buekenhout-Metz unital u in PG(2,q2), arising from an elliptic quadric, is represented in PG(5,q) by an algebraic hypersurface of degree four minus the complement of a line in a three-dimensional subspace. Also, such a hypersurface is reducible if and only if u is classical.
A Framework for Adaptive Routing in Multicomputer Networks
Authors: John Y. Ngai
Venue:  (1989)

Message-passing concurrent computers, also known as multicomputers, such as the Caltech Cosmic Cube [47] and its commercial descendents, consist of many computing nodes that interact with each other by sending and receiving messages over communication channels between the nodes. The communication networks of the second-generation machines, such as the Symult Series 2010 and the Intel iPSC2 [2], employ an oblivious wormhole-routing technique that guarantees deadlock freedom. The network performance of this highly evolved oblivious technique has reached a limit of being capable of delivering, under random traffic, a stable maximum sustained throughput of ~~45 to 50% of the limit set by the network bisection bandwidth, while maintaining acceptable network latency. This thesis examines the possibility of performing adaptive routing as an approach to further improving upon the performance and reliability of these networks. In an adaptive multipath routing scheme, message trajectories are no longer deterministic, but are continuously perturbed by local message loading. Message packets will tend to follow their shortest-distance routes to destinations in normal traffic loading, but can be detoured to longer but less-loaded routes as local congestion occurs. A simple adaptive cut-through packet-switching framework is described, and a number of fundamental issues concerning the theoretical feasibility of the adaptive approach are studied. Freedom of communication deadlock is achieved by following a coherent channel protocol and by applying voluntary misrouting as needed. Packet deliveries are assured by resolving channel-access conflicts according to a priority assignment. Fairness of network access is assured either by sending round-trip packets or by having each node follow a local injection-synchronization protocol. The performance behavior of the proposed adaptive cut-through framework is studied with stochastic modeling and analysis, as well as through extensive simulation experiments for the 2D and 3D rectilinear networks. Theoretical bounds on various average network-performance metrics are derived for these rectilinear networks. These bounds provide a standard frame of reference for interpreting the performance results. In addition to the potential gain in network performance, the adaptive approach offers the potential for exploiting the inherent path redundancy found in richly connected networks in order to perform fault-tolerant routing. Two convexity-related notions are introduced to characterize the conditions under which our adaptive routing formulation is adequate to provide fault-tolerant routing, with minimal change in routing hardware, The effectiveness of these notions is studied through extensive simulations, The 2D octagonal-mesh network is suggested; this displays excellent fault-tolerant potential under the adaptive routing framework. Both performance and reliability behaviors of the octagonal mesh are studied in detail. A number of
Patterns and Aspects for Use Cases: Reuse Techniques for Use Case Descriptions
Authors: Motoshi Saeki
Venue: Proceedings of the 4th International Conference on Requirements Engineering (ICRE'00) (2000)

In this paper, we discuss two types of reusable components for use case descriptions; use case patterns (templates) and aspect patterns.
Planning and Acting in Partially Observable Stochastic Domains
Authors: Leslie P Kaelbling, Michael L. Littman, Anthony R. Cassandra
Venue:  (1996)

In this paper, we bring techniques from operations research to bear on the problem of choosing optimal actions in partially observable stochastic domains. We begin by introducing the theory of Markov decision processes (MDPs) and partially observable MDPs (POMDPs). We then outline a novel algorithm for solving POMDPs off line and show how, in some cases, a finite-memory controller can be extracted from the solution to a POMDP. We conclude with a discussion of the complexity of finding exact solutions to POMDPs and of some possibilities for finding approximate solutions.
Towards a 'Safe' Use of Design Patterns to Improve OO Software Testability
Authors: Benoit Baudry, Yves Le Sunyé, Jean-Marc Jézéquel
Venue: Proceedings of the 12th International Symposium on Software Reliability Engineering (2001)

Design-for-testability is a very important issue in software engineering.It becomes crucial inthe case of OO designs where control flows are generally not hierarchical, but are diffuse and distributed over the whole architecture.We introduce the concept of a "testing conflict" when potentially concurrent client/supplier relationships between the same classes along different paths exist in a system.Such conflicts may be hard to test, especially when dynamic binding and polymorphism are involved.We describe the conflicts using topological classconfiguration diagrams.An overall architecture is represented as a combination of the initial design and several patterns.We focus on the design patterns as coherent subsets in the architecture, and we explain how their use can provide a way for limiting the complexity oftesting for conflicts, and of confining their effects to the classes involved in the pattern.
Model Checking Strategies for Linear Hybrid Systems
Authors: Thomas A. Henzinger, Pei Ho
Venue:  (1994)

Linear hybrid systems are dynamical systems whose variables change both discretely and continuously along piecewise linear trajectories; they are useful for modeling digital real-time programs that are embedded in analog environments. Model checking is an algorithmic technique for anlayzing finitestate systems that has recently been extended to certain infinite-state systems, including linear hybrid systems. The method has been implemented in HyTech (The Cornell Hybrid Technology Tool), a symbolic model checker for linear hybrid systems. We report on a new implementation and several experiments with HyTech. The core of HyTech is a semidecision procedure that, given a linear hybrid automaton describing a system and a temporal formula describing a requirement, computes the so-called target region-the linear set of system states that satisfy the requirement. Unfortunately, the verification procedure may not return the target region using a reasonable amount of time and space, or it may not terminate in principle. Thus we have reimplemented the model checker using more efficient data structures that represent linear state sets geometrically, as unions of convex polyhedra, and we have experimented with several strategies that are designed to improve the performance of the model checker further: we (1) simultaneously compute the target region from different directions, (2) encode data as finite-state control, (3) approximate the target region by dropping constraints, and (4) iteratively refine the approximation until sufficient precision is obtained. Interestingly, symbolic model checking (fixpoint computation by iteration) and the polyhedral approximation strategies (3) can be viewed as the abstract interpretation of linear hybrid systems.
Managing Software Evolution with a Formalized Abstraction Hierarchy
Authors: Timo Aaltonen, Tommi Mikkonen
Venue: Proceedings of the Eighth International Conference on Engineering of Complex Computer Systems (2002)

Complex computer systems are seldom made fromscratch but they contain significant amounts of legacy code,which then is under continuous pressure for evolution.Therefore, a need for a rigorous method for managing evolutionin this setting is evident. In this paper we proposea management method for reactive and distributed systems.The method is based on creating a formal abstraction hierarchyto model the system with abstractions that exceedthose that are used as implementation facilities. This hierarchyis then used to assess the cost of a modification byassociating the modification to appropriate abstractions inthe hierarchy and by determining the abstractions that needto be revisited to retain the hierarchy consistent.