Some relations between Markov algorithms and formal languages

Markov algorithms have received very little attention in the studies about formal languages, so the purpose of the present paper is twofold: i) to characterize languages in terms of Markov algorithms, and ii) to produce automatically Markov algorithms accepting or parsing languages generated by given grammars. We use a particular, although universal, subclass of Markov algorithms, which we call “pointer Markov algorithms»; we obtain a characterization of: i) regular, ii) deterministic context-free, and iii) type O languages, which is quite «natural» in terms of these algorithms. Furthermore, we show that, given a right linear or a strongLL(k) grammar, it is possible to produce automatically a pointer Markov algorithm parsing the language generated by the grammar. These constructions are particularly interesting because pointer Markov algorithms can be compiled conveniently into machine code programs.     

The relation between logic and functional languages: a survey

The paper considers different methods of integrating the functional and logic programming paradigms, starting with the identification of their semantic differences. The main methods to extend functional programs with logic features (i.e. unification) are then considered. These include narrowing, completion, SLD-resolution of equational formulas, and set abstraction. The different techniques are analyzed from several viewpoints, including the ability to support both paradigms, lazy evaluation, and concurrency.     

Rudimentary relations and stack languages

The rudimentary relations, defined by Smullyan (1961), are known to contain the contextfree languages. It is shown here that the one-way stack languages and their complements are also rudimentary.     

The evolution of job control languages

Job control languages are a feature of any large scale operating system. This paper traces the historical development of these languages, and compares two representative examples, OS/360 JCL and GEORGE 3 command language. The paper draws an analogy between job control languages and programming languages, showing that JCL is equivalent to an assembly language, whilst GEORGE 3 command language is like a simple autocode.     

Synchronized behaviours of processes and rational relations

Summary Synchronized behaviours of processes, specified in three different ways, are compared with rational relations.     

On the relation between additive and multiplicative decompositions of rational matrix functions

In this paper, a general frame to study relations between additive and multiplicative representations of rational matrix functions is presented. Various extensions of the positive real lemma, as well as of other classical factorization results, both in the continuous and discrete-time cases, are established. In the case of square factorizations, the map between solutions to an asymmetric algebraic Riccati equation and pairs of factors is shown to be a homeomorphism. In this framework, we also derive a geometric characterization of non-square factorizations.     

Recurrence relations for rational cubic methods I: The Halley method

In this paper we present a system of a priori error bounds for the Halley method in Banach spaces. Our theorem supplies sufficient conditions on the initial point to ensure the convergence of Halley iterates, by means of a system of “recurrence relations”, analogous to those given for the Newton method by Kantorovich, improving previous results by Döring [4]. The error bounds presented are optimal for second degree polynomials. Other rational cubic methods, as the Chebyshev method, will be treated in a subsequent paper.     

Recurrence relations for rational cubic methods II: The Chebyshev method

We continue the analysis of rational cubic methods, initiated in [7]. In this paper, we obtain a system of a priori error bounds for the Chebyshev method in Banach spaces through a local convergence theorem that provides sufficient conditions on the initial point in order to ensure the convergence of Chebyshev iterates. The error estimates are exact for second degree polynomials. We also discuss some applications.     

Contrasting dedicated model transformation languages versus general purpose languages: a historical perspective on ATL versus Java based on complexity and size

Model transformations are among the key concepts of model-driven engineering (MDE), and dedicated model transformation languages (MTLs) emerged with the popularity of the MDE pssaradigm about 15 to 20 years ago. MTLs claim to increase the ease of development of model transformations by abstracting from recurring transformation aspects and hiding complex semantics behind a simple and intuitive syntax. Nonetheless, MTLs are rarely adopted in practice, there is still no empirical evidence for the claim of easier development, and the argument of abstraction deserves a fresh look in the light of modern general purpose languages (GPLs) which have undergone a significant evolution in the last two decades. In this paper, we report about a study in which we compare the complexity and size of model transformations written in three different languages, namely (i) the Atlas Transformation Language (ATL), (ii) Java SE5 (2004–2009), and (iii) Java SE14 (2020); the Java transformations are derived from an ATL specification using a translation schema we developed for our study. In a nutshell, we found that some of the new features in Java SE14 compared to Java SE5 help to significantly reduce the complexity of transformations written in Java by as much as 45%. At the same time, however, the relative amount of complexity that stems from aspects that ATL can hide from the developer, which is about 40% of the total complexity, stays about the same. Furthermore we discovered that while transformation code in Java SE14 requires up to 25% less lines of code, the number of words written in both versions stays about the same. And while the written number of words stays about the same their distribution throughout the code changes significantly. Based on these results, we discuss the concrete advancements in newer Java versions. We also discuss to which extent new language advancements justify writing transformations in a general purpose language rather than a dedicated transformation language. We further indicate potential avenues for future research on the comparison of MTLs and GPLs in a model transformation context.

     

A formal library of set relations and its application to synchronous languages

Set relations are particularly suitable for specifying the small-step operational semantics of synchronous languages. In this paper, a formal library of set relations for the definition, verification of properties, and execution of binary set relations is presented. The formal library consists of a set of theories written in the Prototype Verification System (PVS) that contains definitions and proofs of properties, such as determinism and compositionality, for synchronous relations. The paper also proposes a serialization procedure that enables the simulation of synchronous set relations via set rewriting systems. The library and the serialization procedure are illustrated with the rewriting logic semantics of the Plan Execution Interchange Language (PLEXIL), a rich synchronous plan execution language developed by NASA to support autonomous spacecraft operations.     

The equality of EOL languages and codings of ol languages

It is proved that a language is a coding (a letter-to-letter homomorphism) of a OL language, if, and only if, it is an EOL language.     

Intermediate-level programming languages for on-line data acquisition and control

The concept of an intermediate-level programming language is discussed as the best tool currently available for programming all aspects of real-time data acquisition and control systems, especially those implemented on small and minicomputers.     

基于矢量控制的电动伺服控制系统设计

目前在航空航天等领域,电动伺服系统被越来越多地应用于火箭和导弹的矢量推进控制、飞机和导弹的舵面控制、飞机的转弯和刹车控制等;电动伺服系统作为飞行器控制系统的关键子系统,其性能直接影响着飞行器的机动性能乃至飞行安全,因而对其技术指标和可靠性都有着很高的要求;文章所介绍的电动伺服控制系统采用基于矢量控制的软件策略和基于DSP的电力电子电路设计技术,具有超调小、响应快、抗负载干扰能力强及实时性好等优点,目前已经过工程的应用验证。     

On a relationship between graph L-systems and picture languages

This paper presents the applicability of graph L-systems to the generation of two-dimensional pictures. It is shown that the class of graphs generated by extended tabled node-replacement graph L-systems (ETnGL) contains the class of isometric array languages under some stipulations which are used to regard an array as a graph.     

Proper and stable, minimal MacMillan degrees bases of rational vector spaces

The structure of proper and stable bases of rational vector spaces is investigated. We prove that ift(s)is a rational vector space, then among the proper bases of 3(s) there is a subfamily of proper bases which are 1) stable, 2) have no zeros inCbigcup {infty}and therefore are column (row) reduced at infinity, and 3) their MacMillan degree is minimum among the MacMillan degrees of all other proper bases of 3(s) and it is given by the sum of the MacMillan degrees of their columns taken separately. It is shown that this notion is the counterpart of Forney's concept of a minimal polynomial basis for the family of proper and stable bases of 3(s).     

Decidability and closure properties of weak Petri net languages insupervisory control

We extend the class of control problems that can be modeled by Petri nets considering the notion of weak terminal behavior. Deterministic weak languages represent closed-loop terminal behaviors that may be enforced by nonblocking Petri net supervisors if controllable. The class of deterministic weak PN languages is not closed under the supremal controllable sublanguage operator     

The relation between EA effectiveness and stakeholder satisfaction

Enterprise Architecture (EA) is increasingly being used by large organizations to get a grip on the complexity of their business processes, information systems and technical infrastructure. Although seen as an important instrument to help solve major organizational problems, effectively applying EA seems no easy task. Active participation of EA stakeholders is one of the main critical success factors for EA. This participation depends on the degree in which EA helps stakeholders achieve their individual goals. A highly related topic is effectiveness of EA, the degree in which EA helps to achieve the collective goals of the organization. In this article we present our work regarding EA stakeholder satisfaction and EA effectiveness, and compare these two topics. We found that, regarding EA, the individual goals of stakeholders map quite well onto the collective goals of the organization. In a case study we conducted, we found that the organization is primarily concerned with the final results of EA, while individual stakeholders also worry about the way the architects operate.     

Undecidable problems of decentralized observation and control on regular languages

We introduce a decentralized observation problem, where the system under observation is modeled as a regular language L over a finite alphabet Σ and n subsets of Σ model distributed observation points. A regular language K⊆L models a set of distinguished behaviors, say, correct behaviors of the system. The objective is to check the existence of a function which, given the n observations corresponding to a behavior ρ∈L, decides whether ρ is in K or not. We prove that checking the existence of such a function is undecidable. We then use this result to show undecidability of a decentralized supervisory control problem in the discrete event system framework.