Lambert Meertens
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
Kathleen Fisher Question: Interesting Answer in Algol
10/21/08 cs242! Lisp! Algol 60! Algol 68! Pascal! Kathleen Fisher! ML! Modula! Reading: “Concepts in Programming Languages” Chapter 5 except 5.4.5! Haskell! “Real World Haskell”, Chapter 0 and Chapter 1! (http://book.realworldhaskell.org/)! Many other languages:! Algol 58, Algol W, Euclid, EL1, Mesa (PARC), …! Thanks to John Mitchell and Simon Peyton Jones for some of these slides. ! Modula-2, Oberon, Modula-3 (DEC)! Basic Language of 1960! Simple imperative language + functions! Successful syntax, BNF -- used by many successors! real procedure average(A,n); statement oriented! real array A; integer n; No array bounds.! begin … end blocks (like C { … } )! begin if … then … else ! real sum; sum := 0; Recursive functions and stack storage allocation! for i = 1 step 1 until n Fewer ad hoc restrictions than Fortran! do General array references: A[ x + B[3] * y ] sum := sum + A[i]; Type discipline was improved by later languages! average := sum/n No “;” here.! Very influential but not widely used in US! end; Tony Hoare: “Here is a language so far ahead of its time that it was not only an improvement on its predecessors Set procedure return value by assignment.! but also on nearly all of its successors.”! Question:! Holes in type discipline! Is x := x equivalent to doing nothing?! Parameter types can be arrays, but! No array bounds! Interesting answer in Algol:! Parameter types can be procedures, but! No argument or return types for procedure parameters! integer procedure p; begin Problems with parameter passing mechanisms! -
Edsger Dijkstra: the Man Who Carried Computer Science on His Shoulders
INFERENCE / Vol. 5, No. 3 Edsger Dijkstra The Man Who Carried Computer Science on His Shoulders Krzysztof Apt s it turned out, the train I had taken from dsger dijkstra was born in Rotterdam in 1930. Nijmegen to Eindhoven arrived late. To make He described his father, at one time the president matters worse, I was then unable to find the right of the Dutch Chemical Society, as “an excellent Aoffice in the university building. When I eventually arrived Echemist,” and his mother as “a brilliant mathematician for my appointment, I was more than half an hour behind who had no job.”1 In 1948, Dijkstra achieved remarkable schedule. The professor completely ignored my profuse results when he completed secondary school at the famous apologies and proceeded to take a full hour for the meet- Erasmiaans Gymnasium in Rotterdam. His school diploma ing. It was the first time I met Edsger Wybe Dijkstra. shows that he earned the highest possible grade in no less At the time of our meeting in 1975, Dijkstra was 45 than six out of thirteen subjects. He then enrolled at the years old. The most prestigious award in computer sci- University of Leiden to study physics. ence, the ACM Turing Award, had been conferred on In September 1951, Dijkstra’s father suggested he attend him three years earlier. Almost twenty years his junior, I a three-week course on programming in Cambridge. It knew very little about the field—I had only learned what turned out to be an idea with far-reaching consequences. a flowchart was a couple of weeks earlier. -
A Politico-Social History of Algolt (With a Chronology in the Form of a Log Book)
A Politico-Social History of Algolt (With a Chronology in the Form of a Log Book) R. w. BEMER Introduction This is an admittedly fragmentary chronicle of events in the develop ment of the algorithmic language ALGOL. Nevertheless, it seems perti nent, while we await the advent of a technical and conceptual history, to outline the matrix of forces which shaped that history in a political and social sense. Perhaps the author's role is only that of recorder of visible events, rather than the complex interplay of ideas which have made ALGOL the force it is in the computational world. It is true, as Professor Ershov stated in his review of a draft of the present work, that "the reading of this history, rich in curious details, nevertheless does not enable the beginner to understand why ALGOL, with a history that would seem more disappointing than triumphant, changed the face of current programming". I can only state that the time scale and my own lesser competence do not allow the tracing of conceptual development in requisite detail. Books are sure to follow in this area, particularly one by Knuth. A further defect in the present work is the relatively lesser availability of European input to the log, although I could claim better access than many in the U.S.A. This is regrettable in view of the relatively stronger support given to ALGOL in Europe. Perhaps this calmer acceptance had the effect of reducing the number of significant entries for a log such as this. Following a brief view of the pattern of events come the entries of the chronology, or log, numbered for reference in the text. -
Computer Conservation Society
Computer Conservation Society Aims and objectives The Computer Conservation Society (CCS) is a co-operative venture between the British Computer Society, the Science Museum of London and the Museum of Science and Industry in Manchester. The CCS was constituted in September 1989 as a Specialist Group of the British Computer Society (BCS). It is thus covered by the Royal Charter and charitable status of the BCS. The aims of the CCS are to Promote the conservation of historic computers and to identify existing computers which may need to be archived in the future Develop awareness of the importance of historic computers Encourage research on historic computers and their impact on society Membership is open to anyone interested in computer conservation and the history of computing. The CCS is funded and supported by voluntary subscriptions from members, a grant from the BCS, fees from corporate membership, do- nations, and by the free use of Science Museum facilities. Some charges may be made for publications and attendance at seminars and conferences. There are a number of active Working Parties on specific computer restorations and early computer technologies and software. Younger peo- ple are especially encouraged to take part in order to achieve skills transfer. Resurrection The Bulletin of the Computer Conservation Society ISSN 0958 - 7403 Number 30 Spring 2003 Contents Generous BCS Support for Bombe Rebuild Project Ernest Morris, Chairman 2 AGM 2 News Round-Up 3 Society Activity 6 CCS Collection Policy 11 DAP snippets Brian M Russell 12 CCS Web Site Information 12 British Computer Corporation | a 1956 Venture Hugh McGregor Ross 13 Edsger Dijkstra remembered Brian Shearing 22 Deciphering Ancient Floppy Discs Kevin Murrell 26 The ICL Archive Hamish Carmichael 28 Forthcoming Events 31 Generous BCS Support for Bombe Rebuild Project Ernest Morris, Chairman CCS members will be familiar with the good progress of the Bombe re- build from the regular reports in Resurrection by John Harper, the project manager. -
AB42.4.8 REMARKS on ABSTRACTO Leo Geurts Lambert
AB42 p. 56 AB42.4.8 REMARKS ON ABSTRACTO Leo Geurts Lambert Meertens Mathematlsch Centrum, Amsterdam I. ABSTRACTO LIVES If an author wants to describe an algorithm, he has to choose a vehicle to express himself. The "traditional" way is to give a description in some natural language, such as English. This vehicle has some obvious drawbacks. The most striking one is that of the sloppyness of natural languages. Hill [|] gives a convincing (and hilarious) exposition of ambiguities in ordinary English, quoting many examples from actual texts for instructional or similar purposes. The problem is often not so much that of syntactical ambiguities ("You would not recognise little Johnny now. He has grown another foot.") as that of unintended possible interpretations ("How many times can you take 6 away from a million? [...] I can do this as many times as you like."). A precise and unambiguous description may require lengthy and repetitious phrases. The more precise the description, the more difficult it is to understand for many, if not most, people. Another drawback of natural languages is the inadequacy of referencing or grouping methods (the latter for lack of non-parenthetical parentheses). This tends to give rise to GOTO-like instructions. With the advent of modern computing automata, programming languages have been invented to communicate algorithms to these computers. Programming languages are almost by definition precise and unambiguous. Nevertheless, they do not provide an ideal vehicle for presenting algorithms to human beings. The reason for this is that programming languages require the specification of many details which are relevant for the computing equipment but not for the algorithm proper. -
BASIC Session
BASIC Session Chairman: Thomas Cheatham Speaker: Thomas E. Kurtz PAPER: BASIC Thomas E. Kurtz Darthmouth College 1. Background 1.1. Dartmouth College Dartmouth College is a small university dating from 1769, and dedicated "for the educa- tion and instruction of Youth of the Indian Tribes in this Land in reading, writing and all parts of learning . and also of English Youth and any others" (Wheelock, 1769). The undergraduate student body (now nearly 4000) outnumbers all graduate students by more than 5 to 1, and majors predominantly in the Social Sciences and the Humanities (over 75%). In 1940 a milestone event, not well remembered until recently (Loveday, 1977), took place at Dartmouth. Dr. George Stibitz of the Bell Telephone Laboratories demonstrated publicly for the first time, at the annual meeting of the American Mathematical Society, the remote use of a computer over a communications line. The computer was a relay cal- culator designed to carry out arithmetic on complex numbers. The terminal was a Model 26 Teletype. Another milestone event occurred in the summer of 1956 when John McCarthy orga- nized at Dartmouth a summer research project on "artificial intelligence" (the first known use of this phrase). The computer scientists attending decided a new language was needed; thus was born LISP. [See the paper by McCarthy, pp. 173-185 in this volume. Ed.] 1.2. Dartmouth Comes to Computing After several brief encounters, Dartmouth's liaison with computing became permanent and continuing in 1956 through the New England Regional Computer Center at MIT, HISTORY OF PROGRAMMING LANGUAGES 515 Copyright © 1981 by the Association for Computing Machinery, Inc. -
301669474.Pdf
Centrum voor Wiskunde en Informatica Centre for Mathematics and Computer Science L.G.L.T. Meertens Paramorphisms Computer Science/ Department of Algorithmics & Architecture Report CS-R9005 February Dib'I( I, 1fle.'1 Cootrumvoor ~', ;""'" ,,., tn!o.-1 Y.,'~• Am.,t,..-(,';if'! The Centre for Mathematics and Computer Science is a research institute of the Stichting Mathematisch Centrum, which was founded on February 11, 1946, as a nonprofit institution aiming at the promotion of mathematics, com puter science, and their applications. It is sponsored by the Dutch Govern ment through the Netherlands Organization for the Advancement of Research (N.W.O.). Copyright © Stichting Mathematisch Centrum, Amsterdam Paramorphisms Lambert Meertens CWI, Amsterdam, & University of Utrecht 0 Context This paper is a small contribution in the context of an ongoing effort directed towards the design of a calculus for constructing programs. Typically, the development of a program contains many parts that are quite standard, re quiring no invention and posing no intellectual challenge of any kind. If, as is indeed the aim, this calculus is to be usable for constructing programs by completely formal manipulation, a major concern is the amount of labour currently required for such non-challenging parts. On one level this concern can be addressed by building more or less spe cialised higher-level theories that can be drawn upon in a derivation, as is usual in almost all branches of mathematics, and good progress is being made here. This leaves us still with much low-level laboriousness, like admin istrative steps with little or no algorithmic content. Until now, the efforts in reducing the overhead in low-level formal labour have concentrated on using equational reasoning together with specialised notations to avoid the introduction of dummy variables, in particular for "canned induction" in the form of promotion properties for homomorphisms- which have turned out to be ubiquitous. -
CWI Scanprofile/PDF/300
Centrum voor Wiskunde en lnformatica Centre for Mathematics and Computer Science L.G.L.T. Meertens, S. Pemberton An implementation of the B programming language Department of Computer Science Note CS-N8406 June Biblioiiie.:;I( ~'~'l'i't'Hm.n<' Wi~f.i;r;de- c11 !nform;:,;i:i.C<a - Ams1errJar11 AN IMPLEMENTATION OF THE B PROGRAMMING LANGUAGE L.G.L.T. MEERTENS, S. PEMBERTON CentPe foP Mathematics and ComputeP Science~ AmstePdam Bis a new programming language designed for personal computing. We describe some of the decisions taken in implementing the language, and the problems involved. Note: B is a working title until the language is finally frozen. Then it will acquire its definitive name. The language is entirely unrelated to the predecessor of C. A version of this paper will appear in the proceedings of the Washington USENIX Conference (January 1984). 1982 CR CATEGORIES: 69D44. KEY WORDS & PHRASES: programming language implementation, progrannning envi ronments, B. Note CS-N8406 Centre f~r Mathematics and Computer Science P.O. Box 4079, 1009 AB Amsterdam, The Netherlands I The programming language B B is a programming language being designed and implemented at the CWI. It was originally started in 1975 in an attempt to design a language for beginners as a suitable replacement for BASIC. While the emphasis of the project has in the intervening years shifted from "beginners" to "personal computing", the main design objectives have remained the same: · • simplicity; • suitability for conversational use; • availability of tools for structured programming. The design of the language has proceeded iteratively, and the language as it now stands is the third iteration of this process. -
Die Gruncllehren Cler Mathematischen Wissenschaften
Die Gruncllehren cler mathematischen Wissenschaften in Einzeldarstellungen mit besonderer Beriicksichtigung der Anwendungsgebiete Band 135 Herausgegeben von J. L. Doob . E. Heinz· F. Hirzebruch . E. Hopf . H. Hopf W. Maak . S. Mac Lane • W. Magnus. D. Mumford M. M. Postnikov . F. K. Schmidt· D. S. Scott· K. Stein Geschiiftsfiihrende Herausgeber B. Eckmann und B. L. van der Waerden Handbook for Automatic Computation Edited by F. L. Bauer· A. S. Householder· F. W. J. Olver H. Rutishauser . K. Samelson· E. Stiefel Volume I . Part a Heinz Rutishauser Description of ALGOL 60 Springer-Verlag New York Inc. 1967 Prof. Dr. H. Rutishauser Eidgenossische Technische Hochschule Zurich Geschaftsfuhrende Herausgeber: Prof. Dr. B. Eckmann Eidgenossische Tecbnische Hocbscbule Zurich Prof. Dr. B. L. van der Waerden Matbematisches Institut der Universitat ZUrich Aile Rechte, insbesondere das der Obersetzung in fremde Spracben, vorbebalten Ohne ausdriickliche Genehmigung des Verlages ist es auch nicht gestattet, dieses Buch oder Teile daraus auf photomechaniscbem Wege (Photokopie, Mikrokopie) oder auf andere Art zu vervielfaltigen ISBN-13: 978-3-642-86936-5 e-ISBN-13: 978-3-642-86934-1 DOl: 10.1007/978-3-642-86934-1 © by Springer-Verlag Berlin· Heidelberg 1967 Softcover reprint of the hardcover 1st edition 1%7 Library of Congress Catalog Card Number 67-13537 Titel-Nr. 5l1B Preface Automatic computing has undergone drastic changes since the pioneering days of the early Fifties, one of the most obvious being that today the majority of computer programs are no longer written in machine code but in some programming language like FORTRAN or ALGOL. However, as desirable as the time-saving achieved in this way may be, still a high proportion of the preparatory work must be attributed to activities such as error estimates, stability investigations and the like, and for these no programming aid whatsoever can be of help. -
A DATA DEFINITION FACILITY for PROGRAMMING LANGUAGES By
A DATA DEFINITION FACILITY FOR PROGRAMMING LANGUAGES by T. A. Standish Carnegie Institute of Technology ....... PittsbUrgh, Pennsylvania May 18, 1967 Submitted to the Carnegie Institute of Technology ....... in partial fulfillment of the requirements for the degree of Doctor of Philosophy This work was supported by the Advanced Research Projects Agency of the Office of the Secretary of Defense (SD-146). Abstract This dissertation presents a descriptive notation for data structures which is embedded in a programming language in such a way that the resulting language behaves as a synthetic tool for describing data and processes in a number of application areas. A series of examples including formulae, lists, flow charts, Algol text, files, matrices, organic molecules and complex variables is presented to explore the use of this tool. In addition, a small formal treatment is given dealing with the equivalence of evaluators and their data structures. -ii- Table of Contents Title Page ....................... i Abstract ........................ ii Table of Contents .................... iii Acknowledgments .................... v Chapter I. Introduction .................. 1 Chapter II. A Selective Review of the Work of Others ...... 17 Chapter III. The Data Definition Facility ........... 25 1. Chapter Summary .............. 25 2. General Description .............. 25 3. Component Descriptions ........... 30 4. Elementary Descriptors ........... 34 5. Modified Descriptors ............ 40 6. Descriptor Formulae ............ 48 7. Declaring Descriptor Variables. and Descriptor Procedures ......... 51 8. Predicates, Selectors, Constructors and Declarations ............. 53 9. Constructors ............... 53 10. Selectors ................. 58 11. Predicates ................ 60 12. Declarations ............... 64 13. Reference Variables, Pointer Expressions and the Contents Operation ......... 65 14. Overlay Assignments, Sharing of Structures and Copying of Structures .......... 68 - iii- Table of Contents, Continued 15. -
Publiek Domein Laat Bedrijven Te Veel Invullen
Steven Pemberton, software-uitvinder en bouwer aan het World wide web Publiek domein laat bedrijven te veel invullen De Brit Steven Pemberton is al sinds 1982 verbonden aan het Centrum voor Wiskunde Informatica (CWI) in Amsterdam. Ook hij is een aartsvader van het internet. Specifiek van het World wide web, waarvan hij destijds dicht bij de uitvinding zat. Steven blijft naar de toekomst kijken, nog met dezelfde fraaie idealen. C.V. 19 februari 1953 geboren te Ash, Surrey, Engeland 1972-1975 Programmeur Research Support Unit Sussex University 1975-1977 Research Programmer Manchester University 1977-1982 Docent Computerwetenschap Brighton University 1982-heden Onderzoeker aan het Centrum voor Wiskunde & Informatica (CWI) Verder: 1993–1999 Hoofdredacteur SIGCHI Bulletin en ACM Interactions 1999–2009 Voorzitter HTML en XHTML2 werkgroepen van W3C 2008-heden Voorzitter XForms werkgroep W3C The Internet Guide to Amsterdam Homepage bij het CWI Op Wikipedia 1 Foto’s: Frank Groeliken Tekst: Peter Olsthoorn Steven Pemberton laat zich thuis interviewen, op een typisch Amsterdamse plek aan de Bloemgracht, op de 6e etage van een pakhuis uit 1625 met uitzicht op de Westertoren. Hij schrijft aan een boek, een voortzetting van zijn jaarlijkse lezing in Pakhuis de Zwijger, met in 2011 The Computer as Extended Phenotype (Computers, Genes and You) als titel. Wat is je thema? “De invloed van hard- en software op de maatschappij, vanuit de nieuwe technologie bezien. ‘Fenotype’ gaat over computers als product van onze genen, als een onderdeel van de evolutie. Je kunt de aanwas van succesvolle genen zien als een vorm van leren, of een vorm van geheugen. -
The Essential Turing: Seminal Writings in Computing, Logic, Philosophy, Artificial Intelligence, and Artificial Life: Plus the Secrets of Enigma
The Essential Turing: Seminal Writings in Computing, Logic, Philosophy, Artificial Intelligence, and Artificial Life: Plus The Secrets of Enigma B. Jack Copeland, Editor OXFORD UNIVERSITY PRESS The Essential Turing Alan M. Turing The Essential Turing Seminal Writings in Computing, Logic, Philosophy, Artificial Intelligence, and Artificial Life plus The Secrets of Enigma Edited by B. Jack Copeland CLARENDON PRESS OXFORD Great Clarendon Street, Oxford OX2 6DP Oxford University Press is a department of the University of Oxford. It furthers the University’s objective of excellence in research, scholarship, and education by publishing worldwide in Oxford New York Auckland Cape Town Dar es Salaam Hong Kong Karachi Kuala Lumpur Madrid Melbourne Mexico City Nairobi New Delhi Taipei Toronto Shanghai With offices in Argentina Austria Brazil Chile Czech Republic France Greece Guatemala Hungary Italy Japan South Korea Poland Portugal Singapore Switzerland Thailand Turkey Ukraine Vietnam Published in the United States by Oxford University Press Inc., New York © In this volume the Estate of Alan Turing 2004 Supplementary Material © the several contributors 2004 The moral rights of the author have been asserted Database right Oxford University Press (maker) First published 2004 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, without the prior permission in writing of Oxford University Press, or as expressly permitted by law, or under terms agreed with the appropriate reprographics rights organization. Enquiries concerning reproduction outside the scope of the above should be sent to the Rights Department, Oxford University Press, at the address above.