Decision tables in Algol 60

This paper defines an extension to Algol 60, which allows the programmer to write decision tables in his Algol program. A pre-processor converts the decision tables to Algol, and its output is used as input to the ordinary Algol compiler. The generated Algol program uses a straight-forward and efficient algorithm for choosing the appropriate decision rule.     

A half year's experience with the facit-algol 1 compiler

The Facit-Algol 1 compiler is described briefly. Restrictions compared to Algol 60 and compatibility with other compilers is mentioned. The paper then discusses the experience with the compiler in the areas of teaching, programming, punching, debugging, and program exchanging. The conclusion is that Algol has done well and represents a great step forward.     

146号初等元胞自动机的演化语言的复杂性

Symbolic dynamics of cellular automata is introduced by coarse-graining the temporal evolution orbits. Evolution languages are defined. By using the theory of formal languages and automata, the complexity of evolution languages of the elementary cellular automaton of rule 146 is studied and it is proved that its width 1-evolution language is regular, but for every n ≥ 2 its width n-evolution language is not context-free but context-sensitive. Also, the same results hold for the equivalent （under conjugation） elementary cellular automaton of rule 182.     

A Cosmo-simula program for a simple air-pollution model

With a programmed example, the article introduces Cosmo-Simula, a language designed for the programming of continuous simulation. The language uses the Algol part of Simula for the programming of the algorithmic part and an extension of Cosmo for the programming of the administrative part of the problem. The translator is programmed using the Algol part of Simula and makes the extended Cosmo available for computers with an Algol-compiler.     

Complexity measurement of natural and artificial languages

We compared entropy for texts written in natural languages (English, Spanish) and artificial languages (computer software) based on a simple expression for the entropy as a function of message length and specific word diversity. Code text written in artificial languages showed higher entropy than text of similar length expressed in natural languages. Spanish texts exhibit more symbolic diversity than English ones. Results showed that algorithms based on complexity measures differentiate artificial from natural languages, and that text analysis based on complexity measures allows the unveiling of important aspects of their nature. We propose specific expressions to examine entropy related aspects of tests and estimate the values of entropy, emergence, self‐organization, and complexity based on specific diversity and message length. © 2014 Wiley Periodicals, Inc. Complexity 20: 25–48, 2015     

Coexistence in exotic scenarios of a modified Abrams–Strogatz model

We work on a model that has succeeded in describing real cases of coexistence of two languages within a closed community of speakers, taking into account bilingualism and incorporating a parameter to measure the distance between languages. The dynamics of this model depend on a characteristic exponent, which weighs the power of the size of a group of speakers to attract new members. So far, this model had been solved only when this characteristic exponent is greater than 1. In this article, we have managed to solve the nature of the stability of all the possible situations for this characteristic exponent, that is, when it is less or equal than 1 and covering also the situations produced when it is 0 or negative. We interpret these new situations and find that, even in such exotic scenarios, there are configurations of the resulting societies where all the languages coexist. © 2014 Wiley Periodicals, Inc. Complexity 21: 86–93, 2016     

Notes on top-down languages

Properties of context-free languages and grammars permitting deterministic top-down recognition with bounded lookahead are discussed. In particular, it is shown that for eachk>1 there are such languages requiring a lookahead of at leastk characters.     

Machine dependent programming in common languages

It is suggested that we should distinguish between common programming languages and common solutions to specific problems. A solution may depend on specific machine characteristics even though it is expressed in a common language. It is further suggested that in future common programming languages this should be admitted openly by allowing the programmer to get access to the machine characteristics at hand through Environment Enquiries which are part of the language. Some specific examples of Environment Enquiries are given.An earlier version of this paper was published in ALGOL BULLETIN no. 18, October 1964.     

Array P systems with permitting features

The biologically inspired model, known as P system, has proved to be a general framework for investigating several problems related to computing in different fields. Two-dimensional picture array languages is one such area in which different kinds of P systems have been constructed for picture array generation. Incorporating the feature of permitting symbols in the rules, a new variety of array P system is constructed here for generating picture languages consisting of picture arrays. The advantage of this approach is that there is a reduction in the number of membranes used in the construction, in comparison to the existing array P system models.     

An approach to deciding the observational equivalence of Algol-like languages

We prove that the observational equivalence of third-order finitary (i.e. recursion-free) Idealized Algol (IA) is decidable using Game Semantics. By modelling the state explicitly in our games, we show that the denotation of a term M of this fragment of IA is a compactly innocent strategy-with-state, i.e. the strategy is generated by a finite view function f_M. Given any such f_M, we construct a real-time deterministic pushdown automaton (DPDA) that recognizes the complete plays of the knowing-strategy denotation of M. Since such plays characterize observational equivalence, and there is an algorithm for deciding whether any two DPDAs recognize the same language, we obtain a procedure for deciding the observational equivalence of third-order finitary IA. Restricted to second-order terms, the DPDA representation cuts down to a deterministic finite automaton; thus our approach gives a new proof of Ghica and McCusker’s regular-expression characterization for this fragment. Our algorithmic representation of program meanings, which is compositional, provides a foundation for model-checking a wide range of behavioural properties of IA and other cognate programming languages. Another result concerns second-order IA with full recursion: we show that observational equivalence for this fragment is undecidable.     

Index sets for ω‐languages

An ω‐language is a set of infinite sequences (words) on a countable language, and corresponds to a set of real numbers in a natural way. Languages may be described by logical formulas in the arithmetical hierarchy and also may be described as the set of words accepted by some type of automata or Turing machine. Certain families of languages, such as the languages, may enumerated as P₀, P₁, … and then an index set associated to a given property R (such as finiteness) of languages is just the set of e such that P_e has the property. The complexity of index sets for 7 types of languages is determined for various properties related to the size of the language.     

R: A Language for Data Analysis and Graphics

Abstract

In this article we discuss our experience designing and implementing a statistical computing language. In developing this new language, we sought to combine what we felt were useful features from two existing computer languages. We feel that the new language provides advantages in the areas of portability, computational efficiency, memory management, and scoping.     

一类吸引子的语法复杂性*

本文研究了Feigenbaum吸引子和周期窗口中Feisenbaum吸引子决定的形式语言,讨论了它们的语法复杂性.证明了这类吸引子都是ETOL语言,从而是上下文有关语言(CSL);而不是上下文无关语言(CFL).     

The spline curve,a smooth interpolating function used in numerical design of ship-lines

It has been found that a numerical approximation of a ship-designer's spline results in a smooth interpolating function. An algorithm which computes the function coefficients is presented in Algol. Methods to vary the stiffnes of the spline are included. A test of fairness is described and finally a more elaborate algorithm which leads to a closer approximation is outlined.     

Implementation of a low round-off summation method

The method of Linz [1] for accurate floating-point summation has been programmed in Algol 60. The accuracy obtained confirms the analysis given by Linz. However, similar accuracy may be obtained with the use of quasi-double-precision [2].     

Operads,quasiorders, and regular languages

We generalize the construction of multi-tildes in the aim to provide double multi-tilde operators for regular languages. We show that the underlying algebraic structure involves the action of some operads. An operad is an algebraic structure that mimics the composition of the functions. The involved operads are described in terms of combinatorial objects. These operads are obtained from more primitive objects, namely precompositions, whose algebraic counter-parts are investigated. One of these operads acts faithfully on languages in the sense that two different operators act in two different ways.     

Features of the gier algol 4 system

A brief survey is given of the new features included in the Gier Algol 4 compiler system, as compared with its predecessors. As background the more recent additions to the hardware of the machine are described. The new features primarily aim at a more effective use of the existing machine facilities, including optional facilities existing only in some installations.     

A note on top-down deterministic languages

In recent years attempts have been made to characterize those languages to which deterministic top-down analysis is applicable. This note examines the relationships between the various classes of grammars that are known to this author.Work carried out under the National Science Foundation, Grant NSF-GJ-95.     

A language-driven generalized numerical database translator

Numerical databases arise in many scientific applications to keep track of large dense and sparse matrices, residing on secondary devices in matrix compact data representation. This paper describes a language-driven generalized data translator for translating any numerical database from one matrix compact data representation to another. Our approach is to describe any matrix compact data representation by a physical schema and any numerical database and its mapping to storage by data language facilities. The languages are processed by a Generalized Syntax-Directed Translation Scheme (GSDTS) to automatically generate FORTRAN conversion programs which become the major modules of the translator.