In this paper, we develop a compositional denotational semantics for prioritized real-time distributed programming languages. One of the interesting features is that it extends the existing compositional theory propos...
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In this paper, we develop a compositional denotational semantics for prioritized real-time distributed programming languages. One of the interesting features is that it extends the existing compositional theory proposed by Koymans et al (1988) for prioritized real-time languages preserving the compositionality of the semantics. The language permits users to define situations in which an action has priority over another action without the requirement of preassigning priorities to actions for partially ordering the alphabet of actions. These features are part of the languages such as Ada designed specifically keeping in view the needs of real-time embedded systems. Further, the approach does not have the restriction of other approaches such as prioritized internal moves can preempt unprioritized actions etc. Our notion of priority in the environment is based on the intuition that a low priority action can proceed only if the high priority action cannot proceed due to lack of the handshaking partner at that point of execution. In other words, if some action is possible corresponding to that environment at some point of execution then the action takes place without unnecessary waiting. The proposed semantic theory provides a clear distinction between the semantic model and the execution model - this has enabled us to fully ensure that there is no unnecessary waiting.
A " basic English" to enable editors, writers, librarians, educators, and others to instruct computers to perform mechanical text processing conveniently has been defined (see Tables II to V for partial summ...
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A " basic English" to enable editors, writers, librarians, educators, and others to instruct computers to perform mechanical text processing conveniently has been defined (see Tables II to V for partial summary). It has been given the name SNAP (Stylized Natural Procedural) language for reference. A processor that executes procedures expressed in a subset of this language has worked for some months on several computers. It was used successfully last semester by 40 students with humanities background, in a graduate course in the School of Library Service of Columbia University, for elementary mechanized library and documentation tasks. The processor for the larger subset of the language shown in Tables II to V now works, and is being applied to several practical problems. The processor for the full language is being completed. A SNAP procedure consists of a succession of well-formed English sentences of a few simple types. Most of these begin with imperative verbs that are concerned with input and output operations, and with the manipulation of strings of characters, numbers, and arrays of strings and numbers. Conditional sentences begin with IF. Several constructions that extract and concatenate portions of strings and lists of strings are used in the objects of SNAP sentences. The SNAP processor is written (apart from specialized input-output routines) in FORTRAN IV. It deals directly with some 25 "built-in" verbs, and will allow the user to define further verbs by subroutines that are also written in SNAP.
Peer-to-peer (P2P) networks such as Gnutella and BitTorrent have revolutionised Internet based applications. P2P approaches provide a number of benefits, however most cycle stealing projects, such as SETI@home, have c...
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Query Refinement is an essential information retrieval tool that interactively recommends new terms related to a particular query. This paper introduces concept recall, an experimental measure of an algorithm's ab...
ISBN:
(纸本)0897918363
Query Refinement is an essential information retrieval tool that interactively recommends new terms related to a particular query. This paper introduces concept recall, an experimental measure of an algorithm's ability to suggest terms humans have judged to be semantically related to an information need. This study uses precision improvement experiments to measure the ability of an algorithm to produce single term query modifications that predict a user's information need as partially encoded by the query. An oracle algorithm produces ideal query modifications, providing a meaningful context for interpreting precision improvement results. This study also introduces RMAP, a fast and practical query refinement algorithm that refines multiple term queries by dynamically combining precomputed suggestions for single term queries. RMAP achieves accuracy comparable to a much slower algorithm, although both RMAP and the slower algorithm lag behind the best possible term suggestions offered by the oracle. We believe RMAP is fast enough to be integrated into present day Internet search engines: RMAP computes 100 term suggestions for a 160,000 document collection in 15 ms on a low-end PC.
作者：
Braüner, TorbenProgramming
Logic and Intelligent Systems Research Group Roskilde University DK-4000 Roskilde P.O. Box 260 Denmark
This is primarily a conceptual paper. The goal of the paper is to put into perspective the proof-theory of hybrid logic and in particular, try to give an answer to the following question: Why does the proof-theory of ...
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This is primarily a conceptual paper. The goal of the paper is to put into perspective the proof-theory of hybrid logic and in particular, try to give an answer to the following question: Why does the proof-theory of hybrid logic work so well compared to the proof-theory of ordinary modal logic? Roughly, there are two different kinds of proof systems for modal logic: systems where the formulas involved in the rules are formulas of the object language, that is, ordinary modal-logical formulas, and systems where the formulas involved in the rules are metalingustic formulas obtained by attaching labels representing possible worlds to ordinary modal-logical formulas. systems of the second kind often also involve an explicit representation of the accessibility relation. From a proof-theoretic point of view, modal-logical systems of the first kind are less well-behaved than systems of the second kind. It turns out that this can be remedied by hybridization, that is, hybridization of modal logics enables the formulation of well-behaved proof systems without involving metalinguistic machinery. What has happened is that the metalinguistic machinery has been internalized in the object language. This gives an answer to the initial question, which is that the proof-theory of hybrid logic works so well because the metalinguistic semantic machinery has been internalized in the object language.
Translating time expression into absolute time points or durations is a challenge for natural languages processing such as text mining and text understanding in general. We present a constraint logic language CLP(Time...
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A new language is introduced for describing hypotheses about fluctuations of measurable properties in streams of timestamped data, and as prime example, we consider trends of emotions in the constantly flowing stream ...
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This volume contains papers from the Eighth Z User Meeting, to be held at the University of Cambridge from 29 - 30 June 1994. The papers cover a wide range of issues associated with Z and formal methods, with particul...
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ISBN:
(数字)9781447134527
ISBN:
(纸本)9783540198840
This volume contains papers from the Eighth Z User Meeting, to be held at the University of Cambridge from 29 - 30 June 1994. The papers cover a wide range of issues associated with Z and formal methods, with particular reference to practical application. These issues include education, standards, tool support, and interaction with other design paradigms such as consideration of real-time and object-oriented approaches to development. Among the actual topics covered are: the formal specification in Z of Defence Standard 00-56; formal specification of telephone features; specifying and interpreting class hierarchies in Z; and software quality assurance using the SAZ method.;provides an important overview of current research into industrial applications of Z, and will provide invaluable reading for researchers, postgraduate students and also potential industrial users of Z.
A formal framework for a calculus of real-time systems is presented. Specifications and program statements are combined into a single language called TAM (the Temporal Agent Model), that allows the user to express bot...
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