The Japanese computer industry is organized on different lines to that in the USA or Western Europe. A higher degree of cooperation and coordination characterizes much of Japanese industry, as it does Japanese society...
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The Japanese computer industry is organized on different lines to that in the USA or Western Europe. A higher degree of cooperation and coordination characterizes much of Japanese industry, as it does Japanese society. Nevertheless, there is a fairly close similarity between Japanese and US companies, particularly since the Japanese have begun to decentralize their R&D operations. Many Japanese companies also manufacture American products under licence. The fifth generation computer project, which is an example of Japanese cooperation and willingness to pursue long-term goals is discussed.
The formal verification of control structure implementation techniques is a subject receiving increased attention among programming language researchers. Such correctness arguments relate source language control seman...
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The formal verification of control structure implementation techniques is a subject receiving increased attention among programming language researchers. Such correctness arguments relate source language control semantics to corresponding implementation effects. Most commonly, it is demonstrated that a particular implementation strategy α is “safe” is some source language control disciplineδ is observed. We term this asufficiency proof forδ with given α. In this paper, the companion issue of thenecessity ofδ is explored. That is, we consider the question of whether some more liberal disciplineδ might also be sufficient for α. The motivation is the observation that language designers often have particular control implementation strategies in minda priori, but at times over-restrict their final designs to ensure that the envisioned implementation remains applicable. The general notion of control discipline necessity proofs is illustrated by a proof that Wang and Dahl's CS condition on block-structured coroutines is necessary, given a simple scope-based deletion strategy, but that their CR condition is not necessary unless scope-based referencing constraints are taken into account.
In a Petri Net (PN) model of a system, a small subset of transition can usually be fired. Therefore several special Programmable Logic Controllers (PLCs) have been proposed looking for more performant simulation schem...
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In a Petri Net (PN) model of a system, a small subset of transition can usually be fired. Therefore several special Programmable Logic Controllers (PLCs) have been proposed looking for more performant simulation schemas. Some of them are general purpose microcomputer-based. Others are constructed using specialised microprocessors (microprogrammed or not). This paper presents a conceptual framework to systematize concepts introduced in different PLCs specifically designed for safe (1-bounded) PN simulation. To compare their “conceptual” performances, basic proposed schemas(and other new ones) were programmed on a same microcomputer (M 6801). The technique used for comparison of performances consists of: (1) building different data structures to represent PN and its marking and (2) building performance models using a small set of parameters that caracterizes the complexity of PN-models. It is shown that there is no “optimum” schema. The “best” one is a function of the net to be realised.
The concept of history is introduced to the variables of a programming language. At each execution of assignment statement for a variable x , the current value of x is saved to x 〈1〉, that of x 〈1〉 to x 〈2〉 and ...
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The concept of history is introduced to the variables of a programming language. At each execution of assignment statement for a variable x , the current value of x is saved to x 〈1〉, that of x 〈1〉 to x 〈2〉 and so on automatically. With the aid of this facility, a programmer will not worry about bookkeeping of saving the content of a variable and will make fewer errors in programming. A possible implementation method for the history on a conventional computer is also discussed.
Certain features of programming languages, such as data structure operations and procedure call mechanisms, have been found to resist formalization by conventional program verification techniques. An alternate approac...
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Certain features of programming languages, such as data structure operations and procedure call mechanisms, have been found to resist formalization by conventional program verification techniques. An alternate approach is presented, based on a “situational calculus,” which makes explicit reference to the states of a computation. For each state, a distinction is drawn between an expression, its value, and the location of the *** this conceptual framework, the features of a programming language can be described axiomatically. Programs in the language can then be synthesized, executed, verified, or transformed by performing deductions in this axiomatic system. Properties of entire classes of programs, and of programming languages, can also be expressed and proved in this way. The approach is amenable to machine *** a situational-calculus formalism it is possible to model precisely many “problematic” features of programming languages, including operations on such data structures as arrays, pointers, lists, and records, and such procedure call mechanisms as call by reference, call by value, and call by name. No particular obstacle is presented by aliasing between variables, by declarations, or by recursive *** this paper, we introduce our conceptual framework and present an axiomatic definition of the assignment statement. If suitable restrictions on the programming language are imposed, the well-known Hoare assignment axiom can then be proved as a theorem. However, our definition can also describe the assignment statement of unrestricted programming languages, for which the Hoare axiom does not hold. In forthcoming papers, we apply the situational-calculus framework to the description of data structure operations and procedure call mechanisms.
This paper presents the formal definition of TOMAL (Task-Oriented Microprocessor Applications language), a programming language intended for real-time systems running on small processors. The formal definition address...
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This paper presents the formal definition of TOMAL (Task-Oriented Microprocessor Applications language), a programming language intended for real-time systems running on small processors. The formal definition addresses all aspects of the language. Because some modes of semantic definition seem particularly well-suited to certain aspects of a language, and not as suitable for others, the formal definition employs several complementary modes of *** primary definition is axiomatic and is employed to define most statements of the language. Simple, denotational (but not lattice-theoretic) semantics complement the axiomatic semantics to define type-related features, such as binding of names to types, data type coercions, and evaluation of expressions. Together, the axiomatic and denotational semantics define all features of the sequential language. An operational definition is used to define real-time execution, and to extend the axiomatic definition to account for all aspects of concurrent execution. Semantic constraints, sufficient to guarantee conformity of a program with the axiomatic definition, can be checked by analysis of a TOMAL program at compilation.
Parsing in the syntactical analysis of LR(k) grammars has characteristically demanded knowledge of k lookahead symbols, even though this knowledge is rarely needed. This parsing procedure is one reason why the usual ...
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Parsing in the syntactical analysis of LR(k) grammars has characteristically demanded knowledge of k lookahead symbols, even though this knowledge is rarely needed. This parsing procedure is one reason why the usual parsing tables (UTs) frequently have excessive dimensions. An alternative method applies reduced tables (RTs) to any collection of LR(k) sets of time. More auxiliary tables can be developed as needed to be used by the parser as guides for examining the lookahead symbols that follow the actual token. An example is presented of a parse carried out using RTs.
A set of structures and operations is proposed in terms of which picture processing algorithms can be expressed. The rectangular array model which has traditionally been used for this purpose is discussed and certain ...
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A set of structures and operations is proposed in terms of which picture processing algorithms can be expressed. The rectangular array model which has traditionally been used for this purpose is discussed and certain weaknesses in it are revealed. The structures and operations which comprise the formalism are described. They are based on the concept of a region. As an example an algorithm has been taken from the literature and is described using the formalism.
After a description of the guidelines along which the first experiment (1970-1976) of CAI was organized in France, this experiment is described in detail (training of teachers, hardware configurations, development of ...
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This paper defines a programming language called Edison. The language is suitable both for teaching the principles of concurrent programming and for designing reliable real-time programs for multiprocessor systems. Ed...
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This paper defines a programming language called Edison. The language is suitable both for teaching the principles of concurrent programming and for designing reliable real-time programs for multiprocessor systems. Edison is block structured and includes modules, concurrent statements, and when statements.
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