ppxscal/embedding_network huggingface dataset:
Orthogonal polynomials, random matrices and the numerical inversion of the Laplace transform of positive functions
Authors: Piero Barone
Venue: Journal of Computational and Applied Mathematics (2003)

A method for the numerical inversion of the Laplace transform of a continuous positive function f(t) is proposed. Random matrices distributed according to a Gibbs law whose energy V(x) is a function of f(t) are considered as well as random polynomials orthogonal with respect to w(x)=e-V(x). The equation relating w(x) to the reproducing kernel and to the condensed density of the roots of the random orthogonal polynomials is exploited. Basic results from the theories of orthogonal polynomials, random matrices and random polynomials are revisited in order to provide a unified and almost self-contained context. The qualitative behavior of the solutions provided by the proposed method is illustrated by numerical examples and discussed by using logarithmic potentials with external fields that give insight into the asymptotic behavior of the condensed density when the number of data points goes to infinity.
Parallel Computing as a Commodity
Authors: David Pearson
Venue:  (1998)

Massively parallel computers have become undisputed champions in the supercomputing arena. The global computer industry, however, is increasingly dominated by consumer machines. In this thesis, we argue that everyday computers must become highly parallel machines in order to sustain the performance gains we have come to expect. For parallel computation to become a commodity, there must be an architecture which can be scaled as easily as memory arrays are now. We also need to establish that parallelism can benefit everyday applications and that operating systems for such machines can provide as comfortable and robust an environment as we have on sequential machines. We introduce an architecture based on cellular automata---meshes of simple, locally-connected processors in either 2 or 3 dimensions. We argue that this architecture is easily scalable, and from a theoretical viewpoint it is essentially as efficient as any other scalable architecture. We show two instances of this architecture, a simple one implemented in silicon and a more complex one implemented through a simulator. To show the viability of this architecture for everyday tasks, we have developed fast parallel algorithms for RSA encryption (using residue number systems and a new method for converting one RNS to another) and for document formatting (using a space-filling curve for data layout to achieve optimal $O(\droot{n})$ running time on a $d$-dimensional mesh). We also describe the design of an operating system for a cellular array based on the notion of the OS as the periphery, rather than the kernel, and show several advantages in security and performance this confers. Finally, we investigate the 3-dimensional dynamic allocation problem faced by such a system. This problem is NP-hard even in its static form, but we describe a simple best-fit allocator that works well in practice.
Automated Formal Verification of Protocols
Authors: D. R. Avresky, S. Vassilaras
Venue: Proceedings of the 6th International Conference on Computer Communications and Networks (1997)

We adopt a formalism to describe protocols that is close to the human way of thinking and can be easily used to perform reachability analysis of the described protocol in a state-transition format. This formalism allows for an execution tree (ET) to be generated from a set of assertions such that all paths from the root to the leaves are well-defined formulas. We then extend the formalism with regards to real-time properties. Finally, we present a software verification tool, Verify, that implements the above features in the analysis of protocols.
Tutorial Notes: Models and Paradims of Interaction
Authors: Peter Wegner
Venue:  (1995)

Interaction machines, defined by extending Turing machines with input actions (read statements), are shown to be more expressive than computable functions, providing a counterexample to the hypothesis of Church and Turing that the intuitive notion of computation corresponds to formal computability by Turing machines. The negative result that interaction cannot be modeled by algorithms leads to positive principles of interactive modeling by interface constraints that support partial descriptions of interactive systems whose complete behavior is inherently unspecifiable. The unspecifiability of complete behavior for interactive systems is a computational analog of Godel incompleteness for the integers. Fortunately the complete behavior of interaction machines is not needed to harness their behavior for practical purposes. Interface descriptions are the primary mechanism used by software designers and application programmers for partially describing systems for the purpose of designing, controlling, predicting, and understanding them. Interface descriptions are an example of "harness constraints" that constrain interactive systems so their behavior can be harnessed for useful purposes. We examine both system constraints like transaction correctness and interface constraints for software design and applications. Sections 1, 2, and 3 provide a conceptual framework and theoretical foundation for interactive models, while sections 4, 5, and 6 apply the framework to distributed systems, software engineering, and artificial intelligence. Section 1 explores the design space of interaction machines, section 2 considers the relation between imperative, declarative, and interactive paradigms of computing, section 3 examines the limitations of logic and formal semantics. In section 4 we examine process models, transaction correctness, time, programming languages, and operating systems from the point of view of interaction. In section 5, we examine life-cycle models, object-based design, use-case models, design patterns, interoperability, and coordination. In section 6, we examine knowledge representation, intelligent agents, planning for dynamical systems, nonmonotonic logic, and "can machines think?". The interaction paradigm provides new ways of approaching each of these application areas, demonstrating the value of interac
Data Schema Design as a Schema Evolution Process
Authors: H. A. Proper
Venue:  (1996)

In an information system a key role is played by the underlying data schema. This article starts out from the view that the entire modelling process of an information system''s data schema can be seen as a schema transformation process. A transformation process that starts out with an initial draft conceptual schema and ends with an internal database schema for some implementation platform. This allows us to describe the transformation process of a database design as an evolution of a schema through a universe of data schemas. Doing so, allows for a better understanding of the actual design process, countering the problem of ''software development under the lamppost''. Even when the information system design is finalised, the data schema can evolve further due to changes in the requirements on the system. We present a universe of data schemas that allows us to describe the underlying data schemas at all stages of their development. This universe of data schemas is used as a case study on how to describe the complete evolution of a data schema with all its relevant aspects. The theory is general enough to cater for more modelling concepts, or different modelling approaches. To actually model the evolution of a data schema, we present a versioning mechanism that allows us to model the evolutions of the elements of data schemas and their interactions, leading to a better understanding of a schema design process as a whole. Finally, we also discuss the relationship between this simple versioning mechanism and general purpose version management systems.
Fast Interrupt Priority Management in Operating System Kernels
Authors: Daniel Stodolsky, J. B Chen, Brian N. Bershad
Venue:  (1993)

In this paper we describe a new, low-overhead technique for manipulating processor interrupt state in an operating system kernel. Both uniprocessor and multiprocessor operating systems protect against uniprocessor deadlock and data corruption by selectively enabling and disabling interrupts during critical sections. This happens frequently during latency-critical activities such as IPC, scheduling, and memory management. Unfortunately, the cycle cost of modifying the interrupt mask has increased by an order of magnitude in recent processor architectures. In this paper we describe it optimistic interrupt protection, a technique which substantially reduces the cost of interrupt masking by optimizing mask manipulation for the common case of no interrupts. We present results for the Mach 3.0 microkernel operating system, although the technique is applicable to other kernel architectures, both micro and monolithic, that rely on interrupts to manage devices.
A Framework for Security on NoC Technologies
Authors: Catherine H. Gebotys, Robert J. Gebotys
Venue: Proceedings of the IEEE Computer Society Annual Symposium on VLSI (ISVLSI'03) (2003)

Multiple heterogeneous processor cores, memory cores andapplication specific IP cores integrated in acommunication network, also known as Networks on chips(NoCs), will handle a large number of applicationsincluding security. Although NoCs offer more resistance tobus probing attacks, power/EM attacks and networksnooping attacks are relevant. For the first time aframework for security on NoC at both the network level(or transport layer) and at the core level (or applicationlayer) is proposed. At the network level, each IP core has asecurity wrapper and a key-keeper core is included in theNoC protecting encrypted private and public keys. Usingthis framework, unencrypted keys are prevented fromleaving the cores and NoC. This is crucial to preventuntrusted software on or off the NoC from gaining accessto keys. At the core level (application layer) the securityframework is illustrated with software modification forresistance against power attacks with extremely lowoverheads in energy. With the emergence of secure IPcores in the market and nanometer technologies, a securityframework for designing NoCs is crucial for supportingfuture wireless internet enabled devices.
Improved Approximation Guarantees for Minimum-Weight k-trees and Prize-collecting Salesmen
Authors: Baruch Awerbuch, Yossi Azar, Avrim Blum, Santosh Vempala
Venue:  (1994)

Consider a salesperson that must sell some quota of brushes in order to win a trip to Hawaii. This salesperson has a map (a weighted graph) in which each city has an attached demand specifying the number of brushes that can be sold in that city. What is the best route to take to sell the quota while traveling the least distance possible? Notice that unlike the standard traveling salesman problem, not only do we need to figure out the order in which to visit the cities, but we must decide the more fundamental question: which cities do we want to visit? In this paper we give the first approximation algorithms with poly-logarithmic performance guarantees for this problem, as well as for the slightly more general PCTSP problem of Balas, and a variation we call the "bank-robber problem" (also called the "orienteering problem" by Golden, Levi, and Vohra). We do this by providing an O(log^2 k) approximation to the k-MST problem which is defined as follows. Given an undirected graph on n nodes with non-negative edge weights and an integer k > n, find the tree of least weight that spans k vertices. (If desired, one may specify in the problem a "root vertex" that must be in the tree as well.) Our result improves on the previous best bound of O(k^0.5) of Ravi et al. and comes quite close to the bound of O(log k) of Garg and Hochbaum for the special case of points in 2-dimensional Euclidean space.
Software Standardization Process In Brazil
Authors: Kival C. Weber, Roberto A. R. Almeida, Danilo Scalet, Vanderlei V. Ortêncio
Venue: Proceedings of the 4th IEEE International Symposium and Forum on Software Engineering Standards (1999)

The international standardization effort on software has contributed for the exceptional development of this sector in the last years. Brazil has been participating in the software standardization process, through ABNT - the Brazilian Association for Technical Standards, as a permanent member of the standardization initiatives of ISO/IEC/JTC1 (ISO/IEC Joint Technical Committee for Information Technology).The activities of SC21:10, ABNT's software subcommittee, since its creation in 1992, in Curitiba, capital of the State of Paraná, and the contributions of these activities to the dissemination of software standards and software quality concepts in Brazil, are reported in this paper. SC21:10 focuses its work in two areas: Software Engineering Standards; and Programming Languages, Operating Systems, and Database Standards.The SC21:10 strategies are focused in two main objectives: the production of Brazilian Standards (NBR) on software and the contribution to the international standardization effort on software.
Engineering CORBA-Based Systems for High Performance
Authors: Wai-Keung Wu, Shikharesh Majumdar
Venue: Proceedings of the 2002 International Conference on Parallel Processing (2002)

Inter-operability in heterogeneous distributed systems is often provided with the help of CORBA compliant middleware. Many Distributed Object Computing Systems, however, are characterized by limited heterogeneity. Such systems often contain a subset of components that are written in the same programming language and run on top of the same platform. We present engineering techniques that exploit such limited heterogeneity in systems for achieving high system performance. With these techniques components implemented using diverse programming languages and/or platform use a CORBA compliant middleware, whereas the similar components can use a "Flyover" that employs a separate path between the client and its server and avoids a number of CORBA overheads. Insights into system behavior and performance gained from results of experiments with synthetic workload running on a network of PC's are presented.
Tighter constant-factor time hierarchies
Authors: Amir M. Ben-Amram
Venue: Information Processing Letters (2003)

For certain computational models, a constant-factor time hierarchy theorem is known, showing that a constant-factor difference in time bounds makes a difference in problem-solving power (unlike the situation with Turing machines). In this paper we apply the classic "translational technique" (padding) to these hierarchies and show that they are tighter than indicated by the previous proofs.
Verification Methods for the Divergent Runs of Clock Systems
Authors: Thomas A. Henzinger, Peter W. Kopke
Venue:  (1995)

We present a methodology for proving temporal properties of the divergent runs of reactive systems with real-valued clocks. A run diverges if time advances beyond any bound. Since the divergent runs of a system may satisfy liveness properties that are not satisfied by some convergent runs, the standard proof rules are incomplete if only divergent runs are considered. First, we develop a sound and complete proof calculus for divergence, which is based on translating clock systems into discrete systems. Then, we show that simpler proofs can be obtained for stronger divergence assumptions, such as unknown epsilon-divergence, which requires that all delays have a minimum duration of some unknown constant epsilon. We classify all real-time systems into an infinite hierarchy, according to how well they admit the translation of eventuality properties into equivalent safety properties.
Structural Operational Semantics for Weak Bisimulations
Authors: Bard Bloom
Venue:  (1993)

In this study, we present rule formats for four main notions of bisimulation with silent moves. Weak bisimulation is a congruence for any process algebra defined by WB cool rules; we have similar results for rooted weak bisimulation (Milner''s ``observational equivalence''''), branching bisimulation, and rooted branching bisimulation. The theorems stating that, say, observational equivalence is an appropriate notion of equality for CCS are corollaries of the results of this paper. We also give sufficient conditions under which equational axiom systems can be generated from operational rules. Indeed, many equational axiom systems appearing in the literature are instances of this general theory.
Recurrent neural networks with small weights implement definite memory machines
Authors: Barbara Hammer, Peter Tiňo
Venue: Neural Computation (2003)

Recent experimental studies indicate that recurrent neural networks initialized with "small" weights are inherently biased toward definite memory machines (Tino, Cernansky, & Benusková, 2002a, 2002b). This article establishes a theoretical counterpart: transition function of recurrent network with small weights and squashing activation function is a contraction. We prove that recurrent networks with contractive transition function can be approximated arbitrarily well on input sequences of unbounded length by a definite memory machine. Conversely, every definite memory machine can be simulated by a recurrent network with contractive transition function. Hence, initialization with small weights induces an architectural bias into learning with recurrent neural networks. This bias might have benefits from the point of view of statistical learning theory: it emphasizes one possible region of the weight space where generalization ability can be formally proved. It is well known that standard recurrent neural networks are not distribution independent learnable in the probably approximately correct (PAC) sense if arbitrary precision and inputs are considered. We prove that recurrent networks with contractive transition function with a fixed contraction parameter fulfill the so-called distribution independent uniform convergence of empirical distances property and hence, unlike general recurrent networks, are distribution independent PAC learnable.
Shared Multiple-Valued Decision Diagrams for Multiple-Output Functions
Authors: Hafiz Md., Hasan Babu, Tsutomu Sasao
Venue: Proceedings of the Twenty Ninth IEEE International Symposium on Multiple-Valued Logic (1999)

In this paper, we propose a method to represent multiple-output functions using shared multiple- valued decision diagrams (SMDDs). We show an algorithm for pairing the input variables of binary decision diagrams (BDDs). We also present the pair sifting that moves pairs of 4-valued input variables to speed up the normal sifting, and to produce compact SMDDs. The size of the SMDD is the total number of non-terminal nodes excluding the nodes for output selection variables. We derive the sizes of SMDDs for general functions and symmetric functions. From experimental results, we conjecture that, for n > 1, the sizes of SMDDs for bit-counting functions (wgt n ) and incrementing functions (inc n ) are n [log2 n] + n - 2[log2n] and 2 n - 1, respectively, where n is the number of binary input variables, and b a c denotes the largest integer not greater than a . We also compare our method with other one. Experimental results show the efficiency of our method.
Accurate Static Branch Prediction by Value Range Propagation
Authors: Jason R.C. Patterson
Venue:  (1995)

The ability to predict at compile time the likelihood of a particular branch being taken provides valuable information for several optimizations, including global instruction scheduling, code layout, function inlining, interprocedural register allocation and many high level optimizations. Previous attempts at static branch prediction have either used simple heuristics, which can be quite inaccurate, or put the burden onto the programmer by using execution profiling data or source code hints. This paper presents a new approach to static branch prediction called value range propagation. This method tracks the weighted value ranges of variables through a program, much like constant propagation. These value ranges may be either numeric or symbolic in nature. Branch prediction is then performed by simply consulting the value range of the appropriate variable. Heuristics are used as a fallback for cases where the value range of the variable cannot be determined statically. In the process, value range propagation subsumes both constant propagation and copy propagation. Experimental results indicate that this approach produces significantly more accurate predictions than the best existing heuristic techniques. The value range propagation method can be implemented over any "factored" dataflow representation with a static single assignment property (such as SSA form or a dependence flow graph where the variables have been renamed to achieve single assignment). Experimental results indicate that the technique maintains the linear runtime behavior of constant propagation experienced in practice.
Professional Web Graphics for Non Designers, 1 edition
Authors: Dave Gibbons, Adrian Roselli, Isaac Forman, Nick Boyce
Venue:  (2002)

:Have you ever wished that you could make your web pages look eye catching and professional, as well as having great functionality? Well, look no further. In this book we take you through the basics of web design, demonstrating effective use of color on sites, visual elements that work, and successful use of text. Then we go on to show how to put these elements together to make a well designed, brilliantly laid out web page.
Using SKaMPI for developing high-performance MPI programs with performance portability
Authors: Ralf H. Reussner
Venue: Future Generation Computer Systems (2003)

The current practice of developing high-performance software for parallel computers includes a tuning phase where the software's performance is optimised for a specific hardware platform. This tuning phase often is costly and results in machine-specific, hence, less portable software. In this paper we present a publicly available database providing performance data for operations of the message-passing-interface (MPI) measured on several different platforms. This allows to design MPI programs for performance and portability in early stages of software development. Considering the performance of MPI operations while designing programmes allows the software developer (a) to select the fastest implementation alternative, (b) to write performance portable software (i.e., software showing high performance on several platforms without platform-specific tuning), if possible, and (c) to quantify the tradeoff between ultimate performance and performance portability for different platforms.
A deadlock detection and recovery algorithm using the formalism of a directed graph matrix
Authors: T. F. Leibfried
Venue: ACM SIGOPS Operating Systems Review (1989)

A new method of detecting and resolving deadlocked processes in an operating system or database system is presented. It is based on matric theoretic principles and effectively automates tasks heretofore only achievable via adjacency list representations. Two algorithms are presented with examples for each.
Educating the Programmer: Notation, Proofs, and the Development of Programs
Authors: David Gries
Venue:  (1980)

The current state of affairs in programming is discussed. The opinion is expressed that effective programming requires more ``mathematical maturity'''' than most programmers have. Further, education in formal logicc, which is used (often informally) to reason about programs and specifications, and in a theory of programming could do much to increase the programmer''s competence. Such education could lead to programming becoming more of a science than just an art. Examples are given throughout to support the opinions presented.