Suspension Terms as a Means for Meta-coordination in the μLog Coordination Framework

In this paper we introduce the concept of suspension terms as a reification of the suspension of coordination operations in the Log framework. Each time a coordination operation suspends, a corresponding suspension term is created. By creating primitives that can manipulate the suspension terms, we are able to introduce coordination primitives at the meta-level (e.g., dealing with success, failure, suspension). This is called meta-coordination. In this paper, we introduce the new primitives, give a formal definition of their basic semantics, and argue their expressiveness. The paper is concluded with an argumentation why first order suspension terms suffice and how higher order suspension terms can be replaced by lower order suspension terms.     

A computer checked algebraic verification of a distributed summation algorithm

We present an algebraic verification of Segalls propagation of information with feedback algorithm and we report on the verification of the proof using the PVS system. This algorithm serves as a nice benchmark for verification exercises (see [2, 8, 17]). The verification is based on the methodology presented in [7] and demonstrates its suitability to deliver mechanically verifiable correctness proofs of highly nondeterministic distributed algorithms.The research of the second author was supported by Human Capital Mobility (HCM). The research of the third author was supported by the Netherlands Organization for Scientific Research (NWO) under contract SION 612-33-006.Received October 1988 by J. RushbyRevised July 2004Accepted September 2004 by C. B. Jones     

Compositional checking of satisfaction

We present a compositional method for deciding whether a process satisfies an assertion. Assertions are formulas in a modal -calculus, and processes are drawn from a very general process algebra inspired by CCS and CSP. Well-known operators from CCS, CSP, and other process algebras appear as derived operators. The method iscompositional in the structure of processes and works purely on the syntax of processes. It consists of applying a sequence ofreductions, each of which only takes into account the top-level operator of the process. A reduction transforms a satisfaction problem for a composite process into equivalent satisfaction problems for the immediate subcomponents. Using process variables, systems with underfined subcomponents can be defined, and given an overall requirement to the system,necessary and sufficient conditions on these subcomponents can be found. Hence the process variables make it possible to specify and reason about what are often referred to ascontexts, environments, andpartial implementations. Since reductions are algorithms that work on syntax, they can be considered as forming a bridge between traditional noncompositional model checking and compositional proof systems.     

From Pre-Historic to Post-Modern Symbolic Model Checking

Symbolic model checking, which enables the automatic verification of large systems, proceeds by calculating expressions that represent state sets. Traditionally, symbolic model-checking tools are based on backward state traversal; their basic operation is the function pre, which, given a set of states, returns the set of all predecessor states. This is because specifiers usually employ formalisms with future-time modalities, which are naturally evaluated by iterating applications of pre. It has been shown experimentally that symbolic model checking can perform significantly better if it is based, instead, on forward state traversal; in this case, the basic operation is the function post, which, given a set of states, returns the set of all successor states. This is because forward state traversal can ensure that only parts of the state space that are reachable from an initial state and relevant for the satisfaction or violation of the specification are explored; that is, errors can be detected as soon as possible.In this paper, we investigate which specifications can be checked by symbolic forward state traversal. We formulate the problems of symbolic backward and forward model checking by means of two -calculi. The pre- calculus is based on the pre operation, and the post- calculus is based on the post operation. These two -calculi induce query logics, which augment fixpoint expressions with a boolean emptiness query. Using query logics, we are able to relate and compare the symbolic backward and forward approaches. In particular, we prove that all -regular (linear-time) specifications can be expressed as post- queries, and therefore checked using symbolic forward state traversal. On the other hand, we show that there are simple branching-time specifications that cannot be checked in this way.     

Electro-osmotically controllable multi-flow microreactor

An adjustable diffusion-based microfluidic reactor is presented here, which is based on electro-osmotic guiding of reagent samples. The device consists of a laminar flow chamber with two separate reagent inlets. The position and the width of the two sample streams in the flow chamber can be controlled individually by changing the flow ratio of three parallel guiding buffer streams. Since electro-osmotic flow (EOF) is used for pumping, no external pumps or other moving parts are needed. The region where the diffusive profiles of the two sample streams overlap is used for the reactions. This overlapping region can be manipulated in a predictable way by adjusting the voltages required to generate the respective electro-osmotic flow. Reaction dynamics inside the microreactor is illustrated with a reactant pair of a fluorescent calcium tracer and a calcium chloride solution. An analytical model, which is an analogue of electrical circuits to EOF, was developed and embedded into the LabView control software, allowing real-time control of the microreactor. This paper describes the simulation, fabrication and experimental characterisation of the device.     

A functional programming approach to the specification and verification of concurrent systems

Networks of communicating processes can be viewed as networks of stream transformers and programmed in a lazy functional language. Thus the correctness of concurrent systems can be reduced to the correctness of functional programs. In this paper such correctness is proved formally in the-calculus extended with recursion equations for functional programs. The-calculus is chosen since it allows the definition of properties by least fixed points (induction) as well as by greatest fixed points (coinduction), and since greatest fixed points are useful for formalising properties, such as fairness, of infinitely proceeding programs. Moreover, non-deterministic processes are represented as incompletely specified deterministic processes, that is, as properties of stream transformers. This method is illustrated by proving the correctness of the alternating bit protocol.     

End-to-end communications management using TMN “X” interfaces

The ongoing integration of LANs and WANs to support global communications and businesses and the emergence of integrated broadband communication services has created an increased demand for cooperation between customers, network and service providers to achieve end-to-end service management. Such a cooperation between autonomous authorities, each defining their own administrative management domains, requires the application of an open standardized framework to facilitate and regulate interworking. Such a framework is given by the ITU-T recommendations on TMN, where the so-called X interface is of particular importance for inter-domain management. In this paper, we explain the role of the TMN X interface within an inter-domain TMN architecture supporting end-to-end communications management. We identify the important issues that need to be addressed for the definition and realization of TMN X interfaces and report about our practical experiences with the implementation of TMN X interfaces in the PREPARE project.     

A methodology for designing proof rules for fair parallel programs

We propose a methodology for designing sound and complete proof systems for proving progress properties of parallel programs under various fairness assumptions. Our methodology begins with a branching time temporal logic formula (CTL^*) formula that expresses progress under a fairness assumption. The next step obtains an equivalent fixpoint characterization of this CTL^* formula in the-calculus. The final step uses the fixpoint characterizations to extract proof systems for proving progress under the fairness constraint. The methodology guarantees that the proof rules so obtained are sound and relatively complete in the sense of Cook.     

On the Relationship Between BDI Logics and Standard Logics of Concurrency

The behavior of an agent is mainly governed by the specific way in which it handles the rational balance between information and deliberation. Rao and Georgeff's BDI theory is most popular among the formalisms capturing this very balance. This formalism has been proposed as a language for specifying agents in an abstract manner or, alternatively, for verifying various properties of agents implemented in some other programming language. In mainstream computer science, there are formalisms designed for a purpose similar to the BDI theory; not specifically aiming at agents, but at concurrency in general. These formalisms are known as logics of concurrent programs. In this paper these two frameworks are compared with each other for the first time. The result shows that the basic BDI theory, BDI_CTL*, can be captured within a standard logic of concurrency. The logic which is relevant here is Kozen's propositional -calculus. -calculus turns out to be even strictly stronger in expressive power than BDI_CTL* while enjoying a computational complexity which is not higher than that of BD_CTL*'s small fragment CTL. This correspondence puts us in a position to provide the first axiomatization of Rao and Georgeff's full theory. Immediate consequences for the computational complexity of BDI theory are also explored, both for theorem proving and model checking.     

Global culture, local cultures and the internet: The Thai example

This paper addresses the questions of whether and, if so, how and to what extent the Internet brings about homogenisation of local cultures in the world. It examines a particular case, that of Thai culture, through an investigation and interpretation of a Usenet newsgroup, soc.culture.thai. Two threads of discussion in the newsgroup are selected. One deals with criticisms of the Thai government and political leaders, and the other focuses on whether the Thai language should be a medium, or perhaps the only medium, of communication in the newsgroup. It is found that, instead of erasing local cultural boundaries, creating a worldwide monolithic culture, the Internet reduplicates the existing cultural boundaries. What the Internet does, on the contrary, is to create an umbrella cosmopolitan culture which is necessary for communication among people from disparate cultures. That culture, however, is devoid of thick backgrounds, in Michael Walzer's sense.     

AI & Society and society

This article looks at the broadest implications of public acceptance of AI. A distinction is drawn between conscious belief in a technology, and organic belief where the technology is incorporated into an unconscious world model. The extent to which we feel threatened by AI's apparent denial of spirit is considered, along with a discussion of how people react to this threat. It is proposed that organic acceptance of AI models would lead to a rebirth of popular spiritual concepts as paradoxical as the New Age ideas that have their roots in the theories of physics. Finally the relevance of this speculation is discussed in terms of how it could impinge upon public acceptability of AI technology.     

Analysis of the ∈-Expansion in Turbulence Theory: Approximate Renormalization Group for Diffusion of a Passive Scalar in a Random Velocity Field

The validity of the -expansion in the turbulence problem is discussed using the example of diffusion of a passive scalar in a random velocity field. A generalization of Wilson's rule for calculating a diagram of arbitrary order is introduced. The resulting perturbation series, while having zero radius of convergence, is summed exactly yielding amplitudes which differ from those obtained to lowest order in the -expansion by only a few percent. The properties of the expansion are analyzed in detail and it is shown that various subsets of diagrams, while differing by an infinite number of terms, give close results in the vicinity of the fixed point. This indicates nontrivial compensation of high-order interactions in turbulence. The irrelevance of high-order couplings is demonstrated for arbitrary values of . The quality the approximation is tested by comparison with numerical experiments on diffusion of a passive scalar in a band-limited random velocity field in the limit of infinite Peclet number.     

Searching minimax game trees under memory space constraint

Games such as CHESS, GO and OTHELLO can be represented by minimax game trees. Among various search procedures to solve such game trees,- and SSS^* are perhaps most well known. Although it is proved that SSS^* explores only a subset of the nodes explored by-, - is commonly believed to be faster in real applications, since it requires very little memory space and hence its storage management cost is low. Contrary to this folklore, however, this paper reports, using the OTHELLO game as an example, that SSS^* is much faster than-. It is also demonstrated that SSS^* can be modified to make the required memory space controllable to some extent, while retaining the high efficiency of the original SSS^*.This research was partially supported by the Ministry of Education, Science and Culture of Japan, under a Scientific Grant-in-Aid.     

A Typology of Translation Problems for Eurotra Translation Machines

This paper presents a detailed study of Eurotra Machine Translation engines, namely the mainstream Eurotra software known as the E-Framework, and two unofficial spin-offs – the C,A,T and Relaxed Compositionality translator notations – with regard to how these systems handle hard cases, and in particular their ability to handle combinations of such problems. In the C,A,T translator notation, some cases of complex transfer are wild, meaning roughly that they interact badly when presented with other complex cases in the same sentence. The effect of this is that each combination of a wild case and another complex case needs ad hoc treatment. The E-Framework is the same as the C,A,T notation in this respect. In general, the E-Framework is equivalent to the C,A,T notation for the task of transfer. The Relaxed Compositionality translator notation is able to handle each wild case (bar one exception) with a single rule even where it appears in the same sentence as other complex cases.     

Knowledge discovery and system-user partnership: On a production “adversarial partnership” approach

We examine the relationship between systems and their users from the knowledge discovery perspective. Recently knowledge discovery in databases has made important progress, but it may also bring some potential problems to database design, such as issues related to database security, because an unauthorised user may derive highly sensitive knowledge from unclassified data. In this paper we point out that there is a need for a comprehensive study on knowledge discovery in human-computer symbiosis. Borrowing terms from algorithm design and artificial intelligence literature, we propose a notion called database-user adversarial partnership. We point out that this notion is general enough to cover various knowledge discovery and security of issues related to databases and their users. Furthermore, we point out the notion of database-user adversarial partnership can be further generalised into system-user adversarial partnership. Opportunities provided by knowledge discovery techniques and potential social implications are also discussed.     

The Eigenvalue Problem for the 2D Laplacian in ℋ-Matrix Arithmetic and Application to the Heat and Wave Equation

A class of matrices (-matrices) has recently been introduced by Hackbusch for approximating large and fully populated matrices arising from FEM and BEM applications. These matrices are data-sparse and allow approximate matrix operations of almost linear complexity. In the present paper, we choose a special class of -matrices that provides a good approximation to the inverse of the discrete 2D Laplacian. For these 2D -matrices we study the blockwise recursive schemes for block triangular linear systems of equations and the Cholesky and LDL^T factorization in an approximate arithmetic of almost linear complexity. Using the LDL^T factorization we compute eigenpairs of the discrete 2D Laplacian in -matrix arithmetic by means of a so-called simultaneous iteration for computing invariant subspaces of non-Hermitian matrices due to Stewart. We apply the -matrix techniques to approximate the solutions of the high-frequency 2D wave equation for smooth initial data and the 2D heat equation for arbitrary initial data by spectral decomposition of the discrete 2D Laplacian in, up to logarithmic factors, optimal complexity.     

Understanding Computer-based “Informated” Environments

The paper introduces the concept of Computer-based Informated Environments (CBIEs) to indicate an emergent form of work organisation facilitated by information technology. It first addresses the problem of inconsistent meanings of the informate concept in the literature, and it then focuses on those cases which, it is believed, show conditions of plausible informated environments. Finally, the paper looks at those factors that when found together contribute to building a CBIE. It makes reference to CBIEs as workplaces that comprise a non-technocentric perspective and questions whether CBIEs truly represent an anthropocentric route of information technology.     

A Mathematical Analysis of Pānini’s <Emphasis Type="Italic">Śivasūtras</Emphasis>

In Pninis grammar of Sanskrit one finds the ivastras, a table which defines the natural classes of phonological segments in Sanskrit by intervals. We present a formal argument which shows that, using his representation method, Pninis way of ordering the phonological segments to represent the natural classes is optimal. The argument is based on a strictly set-theoretical point of view depending only on the set of natural classes and does not explicitly take into account the phonological features of the segments, which are, however, implicitly given in the way a language clusters its phonological inventory. The key idea is to link the graph of the Hasse-diagram of the set of natural classes closed under intersection to ivastra-style representations of the classes. Moreover, the argument is so general that it allows one to decide for each set of sets whether it can be represented with Pninis method. Actually, Pnini had to modify the set of natural classes to define it by the ivastras (the segment h plays a special role). We show that this modification was necessary and, in fact, the best possible modification. We discuss how every set of classes can be modified in such a way that it can be defined in a ivastra-style representation.¹     

T-Efficient Calculation of the ∈-Solutions to Problems of Calculus and Applied Mathematics. I

An approach to construction of the efficient by complexity algorithms for calculation of -solutions is presented for problems of calculus and applied mathematics. The reserves which can be used in this approach are revealed. The present approach is illustrated by two classes of problems: approximation of functions and numerical integration.     

Intelligent Manufacturing:Present State and Future Trends

AI methods are introduced to an increasing extent in the field of CIM and robotics. This development results in intelligent CIM components – ICAD, ICAP, ICAM, ICAQ – and in intelligent manufacturing systems (IMS) as well as in intelligent robots. This new philosophy requires a lot of prerequisites and research. ICIM or IMS is partially introduced in industry but mainly for large companies. AI as knowledge based and expert systems is ready to be introduced in an efficient way in CIM components. Intelligent, mobile robots as integrated parts of CIM and IMS are ready to be used in factory automation. One of the next steps could be the introduction of Multi-Agent and/or holonic systems. In this contribution the history and the present state of flexible manufacturing, with special emphasis on robotics, are described and further trends in development – Multi Agent Systems – are discussed mainly from the viewpoint of SMEs.