In this paper we present the ObjectMath language, a hybrid language integrating object-oriented constructs with features for symbolic and numeric computation. Complex mathematical models may be implemented in a natura...
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作者：
Jones, Mark P.Programming Research Group
Oxford University UK Department of Computer Science Yale University Yale Station New Haven CT 06520-2158 PO Box 2158 United Kingdom
This paper presents a simple framework for performing calculations with the elements of (finite) lattices. A particular feature of this work is the use of type classes to enable the use of overloaded function symbols ...
In this paper we are interested in general properties of classes of transition system specifications in Plotkin style. The discussion takes place in a setting of labelled transition systems. The states of the transiti...
In this paper we are interested in general properties of classes of transition system specifications in Plotkin style. The discussion takes place in a setting of labelled transition systems. The states of the transition systems are terms generated by a single sorted signature and the transitions between states are defined by conditional rules over the syntax. It is argued that in this setting it is natural to require that strong bisimulation equivalence be a congruence on the states of the transition systems. A general format, called the tyft/tyxt format, is presented for the rules in a transition system specification, such that bisimulation is always a congruence when all the rules fit this format. With a series of examples it is demonstrated that the tyft/tyxt format cannot be generalized in any obvious way. Another series of examples illustrates the usefulness of our congruence theorem. Briefly we touch upon the ❉ of modularity of transition system specifications. It is argued that certain pathological tyft/tyxt rules (the ones which are not pure) can be disqualified because they behave badly with respect to modularization. Next we address the ❉ of full abstraction. We characterize the completed trace congruence induced by the operators in pure tyft/tyxt format as 2-nested simulation equivalence. The pure tyft/tyxt format includes the format given by de Simone (Theoret. Comput. Sci.37, 245–267 (1985)) but is incomparable to the GSOS format of Bloom, Istrail, and Meyer (in“Conference Record of the 15th Annual Symposium on Principles of programming Languages, San Diego, California, 1988,” pp. 229–239). However, it turns out that 2-nested simulation equivalence strictly refines the completed trace congruence induced by the GSOS format.
A multi-language-based data interface system for heterogeneous distributed processing is introduced. A prototyped environment based on this system is discussed, and an evaluation of the prototyped system is presented....
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An algorithm for computing a complete set of unifiers for two terms involving associative-commutative function symbols is presented. It is based on a nondeterministic algorithm given by the authors in 1986 to show the...
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An algorithm for computing a complete set of unifiers for two terms involving associative-commutative function symbols is presented. It is based on a nondeterministic algorithm given by the authors in 1986 to show the NP-completeness of associative-commutative unifiability. The algorithm is easy to understand, and its termination can be easily established. Its complexity is easily analyzed and shown to be doubly exponential in the size of the input terms. The analysis also shows that there is a double-exponential upper bound on the size of a complete set of unifiers of two input terms. Since there is a family of simple associative-commutative unification problems which have complete sets of unifiers whose size is doubly exponential, the algorithm is optimal in its order of complexity in this sense.< >
A multi-language-based data interface system for heterogeneous distributed processing is introduced. A prototyped environment based on this system is discussed, and an evaluation of the prototyped system is presented....
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A multi-language-based data interface system for heterogeneous distributed processing is introduced. A prototyped environment based on this system is discussed, and an evaluation of the prototyped system is presented. It is shown that by keeping the syntax of the specification language flexible and close to existing high-level languages, a user can learn the interface language quickly. Semantically, this data interface views structured data as consisting of two parts: the data values themselves and the representation of the structure among the data values. Through this separation, it is possible to have pipelined data type checking and data conversion operations.< >
The safety of software is becoming increasingly important as computers pervade control systems on which human life depends. Whilst hardware has become significantly more reliable over the years, the same cannot be sai...
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The safety of software is becoming increasingly important as computers pervade control systems on which human life depends. Whilst hardware has become significantly more reliable over the years, the same cannot be said of software. This has become more complex and methods to ensure its correctness have been slow in development. One approach is to mathematically verify software in such systems. This paper investigates the industrial use of these techniques, their advantages and disadvantages, and the introduction of standards and their recommendations concerning formal methods in this area. The cost of safety is also considered.
This paper considers a range of theoretical approaches to the understanding of organisations and the implications these views have for the design of computer supported cooperative work systems. Organisations have ofte...
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作者：
J.B.ROSEN薛国良Computer Science Department
University of MinnesotaMinneapolisMN 55455USA Institute of Operations Research
Qufu Normal University Qufu 278165 Chinahe Euclidean single facility location problem (ESFL) and the Euclidean multiplicity lo-cation problem (EMFL) are two special nonsmooth convex programming problems which haveattracted a largr literature. For the ESFL problem. there are algorithms which converge bothglobally and quadratically For the EMFL problem there are some quadratically convergentalgorithms. but for global convergencel they all need nontrivial assumptions on the problem.In this paper we present an algorithm for EMFL. With no assumption on the problem it isproved that from any initial point this algorithm generates a sequence of points which convergesto the closed convex set of optimal solutions of EMFL.
The Euclidean single facility location problem (ESFL) and the Euclidean multiplicity lo-cation problem (EMFL) are two special nonsmooth convex programming problems which haveattracted a largr literature. For the ESFL ...
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The Euclidean single facility location problem (ESFL) and the Euclidean multiplicity lo-cation problem (EMFL) are two special nonsmooth convex programming problems which haveattracted a largr literature. For the ESFL problem. there are algorithms which converge bothglobally and quadratically For the EMFL problem, there are some quadratically convergentalgorithms. but for global convergencel they all need nontrivial assumptions on the *** this paper, we present an algorithm for EMFL. With no assumption on the problem, it isproved that from any initial point, this algorithm generates a sequence of points which convergesto the closed convex set of optimal solutions of EMFL.
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