Computer Science: Reflections On
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Computational Learning Theory: New Models and Algorithms
Computational Learning Theory: New Models and Algorithms by Robert Hal Sloan S.M. EECS, Massachusetts Institute of Technology (1986) B.S. Mathematics, Yale University (1983) Submitted to the Department- of Electrical Engineering and Computer Science in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the MASSACHUSETTS INSTITUTE OF TECHNOLOGY June 1989 @ Robert Hal Sloan, 1989. All rights reserved The author hereby grants to MIT permission to reproduce and to distribute copies of this thesis document in whole or in part. Signature of Author Department of Electrical Engineering and Computer Science May 23, 1989 Certified by Ronald L. Rivest Professor of Computer Science Thesis Supervisor Accepted by Arthur C. Smith Chairman, Departmental Committee on Graduate Students Abstract In the past several years, there has been a surge of interest in computational learning theory-the formal (as opposed to empirical) study of learning algorithms. One major cause for this interest was the model of probably approximately correct learning, or pac learning, introduced by Valiant in 1984. This thesis begins by presenting a new learning algorithm for a particular problem within that model: learning submodules of the free Z-module Zk. We prove that this algorithm achieves probable approximate correctness, and indeed, that it is within a log log factor of optimal in a related, but more stringent model of learning, on-line mistake bounded learning. We then proceed to examine the influence of noisy data on pac learning algorithms in general. Previously it has been shown that it is possible to tolerate large amounts of random classification noise, but only a very small amount of a very malicious sort of noise. -
Extending Gnu Troff to Produce Html Through The
G. MULLEY and W.LEMBERG: EXTENDING GNU TROFF TOPRODUCE HTML EXTENDING GNU TROFF TOPRODUCE HTML THROUGH THE TECHNIQUE OF NEXT EVENT SIMULATION GAIUS MULLEY,WERNER LEMBERG School of Computing,University of Glamorgan, CF37 1DL, UK E-Mail: [email protected] Kl. Beurhausstr.1,44137 Dortmund, Germany E-Mail: [email protected] Abstract: This paper reports on a technique used to generate accurate HTML output from GNU Troff. GNU Troff is a typesetting package which reads plain text mixed with formatting commands and produces formatted output. It supports a number of devices and nowsupports the production of HTML.The paper discusses the design of the HTML device driver grohtml and modifications made to GNU Troff. The front end program troff wasmodi- fied to maintain a reduced state machine which is examined each time a glyph is passed to the back end device driver(post-grohtml). Anychange in system state between the production of twoglyphs results in a sequence of events being passed to the device driver. There is a direct correspondence between this technique and creating ascript for a next event simulation queue. Furthermore the device driverreconstructs the system state and for- mats the HTML according to state changes caused when processing the event queue. This technique works well, as it minimises the state information passed from front end to back end device driverwhilst still preserving the high levellayout of the text. Using this technique GNU Troffeffectively translates input source into another mark-up language and thus this technique could be extended to translate GNU Troffdocuments into anyofthe OpenOffice supported formats. -
Security Analysis of Cryptographically Controlled Access to XML Documents
Security Analysis of Cryptographically Controlled Access to XML Documents ¤ Mart´in Abadi Bogdan Warinschi Computer Science Department Computer Science Department University of California at Santa Cruz Stanford University [email protected] [email protected] ABSTRACT ments [4, 5, 7, 8, 14, 19, 23]. This line of research has led to Some promising recent schemes for XML access control em- e±cient and elegant publication techniques that avoid data ploy encryption for implementing security policies on pub- duplication by relying on cryptography. For instance, us- lished data, avoiding data duplication. In this paper we ing those techniques, medical records may be published as study one such scheme, due to Miklau and Suciu. That XML documents, with parts encrypted in such a way that scheme was introduced with some intuitive explanations and only the appropriate users (physicians, nurses, researchers, goals, but without precise de¯nitions and guarantees for the administrators, and patients) can see their contents. use of cryptography (speci¯cally, symmetric encryption and The work of Miklau and Suciu [19] is a crisp, compelling secret sharing). We bridge this gap in the present work. We example of this line of research. They develop a policy query analyze the scheme in the context of the rigorous models language for specifying ¯ne-grained access policies on XML of modern cryptography. We obtain formal results in sim- documents and a logical model based on the concept of \pro- ple, symbolic terms close to the vocabulary of Miklau and tection". They also show how to translate consistent poli- Suciu. We also obtain more detailed computational results cies into protections, and how to implement protections by that establish security against probabilistic polynomial-time XML encryption [10]. -
Reflections on Software Research
TURING AWARD LECTURE Reflections on Software Research Can the circumstances that existed in Bell Labs that nurtured the UNIX project be produced again? DENNIS M. RITCHIE The UNIX 1 operating system has suddenly become System V is a supported product on several different news, but it is not new. It began in 1969 when Ken hardware lines, most recently including the 3B systems Thompson discovered a little-used PDP-7 computer and designed and built by AT&T. set out to fashion a computing environment that he UNIX is in wide use, and is now even spoken of as a liked. His work soon attracted me; I joined in the enter- possible industry standard. How did it come to suc- prise, though most of the ideas, and most of the work ceed? for that matter, were his. Before long, others from our There are, of course, its technical merits. Because the group in the research area of AT&T Bell Laboratories system and its history have been discussed at some were using the system; Joe Ossanna, Doug McIlroy, and length in the literature [6, 7, 11], I will not talk about Bob Morris were especially enthusiastic critics and con- these qualities except for one; despite its frequent sur- tributors. In 1971, we acquired a PDP-11, and by the face inconsistency, so colorfully annotated by Don Nor- end of that year we were supporting our first real users: man in his Datamation article [4] and despite its rich- three typists entering patent applications. In 1973, the ness, UNIX is a simple, coherent system that pushes a system was rewritten in the C language, and in that few good ideas and models to the limit. -
ITERATIVE ALGOR ITHMS for GLOBAL FLOW ANALYSIS By
ITERATIVE ALGOR ITHMS FOR GLOBAL FLOW ANALYSIS bY Robert Endre Tarjan STAN-CS-76-547 MARCH 1976 COMPUTER SCIENCE DEPARTMENT School of Humanities and Sciences STANFORD UN IVERS ITY Iterative Algorithms for Global Flow Analysis * Robert Endre Tarjan f Computer Science Department Stanford University Stanford, California 94305 February 1976 Abstract. This paper studies iterative methods for the global flow analysis of computer programs. We define a hierarchy of global flow problem classes, each solvable by an appropriate generalization of the "node listing" method of Kennedy. We show that each of these generalized methods is optimum, among all iterative algorithms, for solving problems within its class. We give lower bounds on the time required by iterative algorithms for each of the problem classes. Keywords: computational complexity, flow graph reducibility, global flow analysis, graph theory, iterative algorithm, lower time bound, node listing. * f Research partially supported by National Science Foundation grant MM 75-22870. 1 t 1. Introduction. A problem extensively studied in recent years [2,3,5,7,8,9,12,13,14, 15,2'7,28,29,30] is that of globally analyzing cmputer programs; that is, collecting information which is distributed throughout a computer program, generally for the purpose of optimizing the program. Roughly speaking, * global flow analysis requires the determination, for each program block f , of a property known to hold on entry to the block, independent of the path taken to reach the block. * A widely used amroach to global flow analysis is to model the set of possible properties by a semi-lattice (we desire the 'lmaximumtl property for each block), to model the control structure of the program by a directed graph with one vertex for each program block, and to specify, for each branch from block to block, the function by which that branch transforms the set of properties. -
Second International Computer Programming Education Conference
Second International Computer Programming Education Conference ICPEC 2021, May 27–28, 2021, University of Minho, Braga, Portugal Edited by Pedro Rangel Henriques Filipe Portela Ricardo Queirós Alberto Simões OA S I c s – Vo l . 91 – ICPEC 2021 www.dagstuhl.de/oasics Editors Pedro Rangel Henriques Universidade do Minho, Portugal [email protected] Filipe Portela Universidade do Minho, Portugal [email protected] Ricardo Queirós Politécnico do Porto, Portugal [email protected] Alberto Simões Politécnico do Cávado e Ave, Portugal [email protected] ACM Classifcation 2012 Applied computing → Education ISBN 978-3-95977-194-8 Published online and open access by Schloss Dagstuhl – Leibniz-Zentrum für Informatik GmbH, Dagstuhl Publishing, Saarbrücken/Wadern, Germany. Online available at https://www.dagstuhl.de/dagpub/978-3-95977-194-8. Publication date July, 2021 Bibliographic information published by the Deutsche Nationalbibliothek The Deutsche Nationalbibliothek lists this publication in the Deutsche Nationalbibliografe; detailed bibliographic data are available in the Internet at https://portal.dnb.de. License This work is licensed under a Creative Commons Attribution 4.0 International license (CC-BY 4.0): https://creativecommons.org/licenses/by/4.0/legalcode. In brief, this license authorizes each and everybody to share (to copy, distribute and transmit) the work under the following conditions, without impairing or restricting the authors’ moral rights: Attribution: The work must be attributed to its authors. The copyright is retained by the corresponding authors. Digital Object Identifer: 10.4230/OASIcs.ICPEC.2021.0 ISBN 978-3-95977-194-8 ISSN 1868-8969 https://www.dagstuhl.de/oasics 0:iii OASIcs – OpenAccess Series in Informatics OASIcs is a series of high-quality conference proceedings across all felds in informatics. -
A Auxiliary Definitions
A Auxiliary Definitions This appendix contains auxiliary definitions omitted from the main text. Variables fun lvars :: com ⇒ vname set where lvars SKIP = {} lvars (x ::= e)={x} lvars (c1;; c2)=lvars c1 ∪ lvars c2 lvars (IF b THEN c1 ELSE c2)=lvars c1 ∪ lvars c2 lvars (WHILE b DO c)=lvars c fun rvars :: com ⇒ vname set where rvars SKIP = {} rvars (x ::= e)=vars e rvars (c1;; c2)=rvars c1 ∪ rvars c2 rvars (IF b THEN c1 ELSE c2)=vars b ∪ rvars c1 ∪ rvars c2 rvars (WHILE b DO c)=vars b ∪ rvars c definition vars :: com ⇒ vname set where vars c = lvars c ∪ rvars c Abstract Interpretation fun strip :: aacom⇒ com where strip (SKIP {P})=SKIP strip (x ::= e {P})=x ::= e © Springer International Publishing Switzerland 2014 281 T. Nipkow and G. Klein, Concrete Semantics, DOI 10.1007/978-3-319-10542-0 282 A Auxiliary Definitions strip (C 1;;C 2)=strip C 1;; strip C 2 strip (IF b THEN {P 1} C 1 ELSE {P 2} C 2 {P})= IF b THEN strip C 1 ELSE strip C 2 strip ({I } WHILE b DO {P} C {Q})=WHILE b DO strip C fun annos :: aacom⇒ a list where annos (SKIP {P})=[P] annos (x ::= e {P})=[P] annos (C 1;;C 2)=annos C 1 @ annos C 2 annos (IF b THEN {P 1} C 1 ELSE {P 2} C 2 {Q})= P 1 # annos C 1 @ P 2 # annos C 2 @ [Q] annos ({I } WHILE b DO {P} C {Q})=I # P # annos C @ [Q] fun asize :: com ⇒ nat where asize SKIP = 1 asize (x ::= e)=1 asize (C 1;;C 2)=asize C 1 + asize C 2 asize (IF b THEN C 1 ELSE C 2)=asize C 1 + asize C 2 + 3 asize (WHILE b DO C )=asize C + 3 definition shift :: (nat ⇒ a) ⇒ nat ⇒ nat ⇒ a where shift f n =(λp. -
Introduction to Linux
Introduction to Linux Yuwu Chen HPC User Services LSU HPC LONI [email protected] Louisiana State University Baton Rouge June 17, 2020 Why you should learn Linux? . Linux is everywhere, not just on HPC . Linux is used on most web servers. Google or Facebook . Android phone . Linux is free and you can personally use it . You will learn how hardware and operating systems work . A better chance of getting a job Introduction to Linux 2 Why Linux for HPC - 2014 OS family system share OS family performance share http://www.top500.org/statistics/list/ November 2014 Introduction to Linux 3 Why Linux for HPC - 2019 OS family system share OS family performance share Linux is the most popular OS used in supercomputers http://www.top500.org/statistics/list/ November 2019 Introduction to Linux 4 Roadmap • What is Linux • Linux file system • Basic commands • File permissions • Variables • Use HPC clusters • Processes and jobs • File editing Introduction to Linux 5 History of Linux (1) . Unix was initially designed and implemented at AT&T Bell Labs 1969 by Ken Thompson, Dennis Ritchie, Douglas McIlroy, and Joe Ossanna . First released in 1971 and was written in assembly language . Re-written in C by Dennis Ritchie in 1973 for better portability (with exceptions to the kernel and I/O) Introduction to Linux 6 History of Linux (2) . Linus Torvalds, a student at University of Helsinki began working on his own operating system, which became the "Linux Kernel", 1991 . Linus released his kernel for free download and helped further development Introduction to Linux 7 History of Linux (3) . -
Concept Learning
Unit 3 Milestones and Giants in IT Industry Concept Learning The Birth of Unix Kenneth "Ken" Thompson (born February 4, 1943), commonly referred to as Ken in hacker circles, is an American pioneer of computer science. Having worked at Bell Labs for most of his career, Thompson designed and implemented the original Unix operating system. He also invented the B programming language, the direct predecessor to the C programming language, and was one of the creators and early developers of the Plan 9 operating systems. Since 2006, Thompson has worked at Google, where he co-invented the Go programming language. In 1983, Thompson and Ritchie jointly received the Turing Award "for their development of generic operating systems theory and specifically for the implementation of the UNIX operating system." C Ken Ken Thompson and Dennis Ritchie (standing) at Bell Labs, 1972 In the end of 1960s, the young engineer at AT&T Bell Labs Kenneth (Ken) Thompson worked on the project of Multics operating system. Multics (Multiplexing Information and Computer Services) was an experimental operating system for GE-645 mainframe, developed in 1960s by Massachusetts Institute of Technology, Bell Labs, and General Electric. It introduced many innovations, but had many problems. 1969 was that magic year in which mankind first went to the moon, ARPANET (the precursor to the Internet) was launched, UNIX was born, and a number of other interesting events occurred. It was also the year that Thompson wrote the game Space Travel. In 1969, frustrated by the slow progress and difficulties, Bell Labs withdrew from the MULTICS project and Thompson decided to write his own operating system, in large part because he wanted a decent system on which to run his game, Space Travel, on the PDP-7. -
Statement on the Selection of Jeffrey Ullman for a Turing Award
Statement on the Selection of Jeffrey Ullman for a Turing Award An Open Letter to Committee of the ACM A.M. Turing Award and ACM: Date: 04/16/2021 Professor Jeffrey D. Ullman of Stanford University has been chosen to receive the 2020 ACM A.M. Turing Award, generally regarded as the highest distinction in computing. While we agree that the technical and educational contributions of Professor Ullman could meet the bar for a “Nobel Prize of Computing”, we condemn the selection as one that directly goes against the Diversity and Inclusion (D & I) values that the Computer Science community, and the Association for Computing Machinery (ACM) in particular, aim to uphold. While we recognize Professor Ullman’s freedom of speech and freedom to hold and express his political views, we are concerned by his sustained discriminatory behavior against students and by ACM bestowing upon such a person an award named after Alan Turing, someone who suffered much discrimination in his tragic life [1]. ACM defines its mission as follows: “ACM is a global scientific and educational organization dedicated to advancing the art, science, engineering, and application of computing, serving both professional and public interests by fostering the open exchange of information and by promoting the highest professional and ethical standards.” Furthermore, ACM explicitly defines “Diversity and Inclusion” as one of its four core values [2]. We assert, based on documented evidence, that not only has Professor Ullman willfully violated the “highest professional and ethical standards” that ACM has the mission to uphold, but also that he has demonstrated a pattern of actively turning against the values of D & I for decades. -
Nroff/Troff User's Manual
AT&T Bell Laboratories Murray Hill, New Jersey 07974 Computing Science Technical Report No. 54 Troff User's Manual² Joseph F. Ossanna Brian W. Kernighan Revised November, 1992 Troff User's Manual² Joseph F. Ossanna Brian W. Kernighan AT&T Bell Laboratories Murray Hill, New Jersey 07974 Revised November, 1992 Troff User's Manual² Joseph F. Ossanna Brian W. Kernighan AT&T Bell Laboratories Murray Hill, New Jersey 07974 Introduction Troff and nroff are text processors that format text for typesetter- and typewriter-like terminals, respectively. They accept lines of text interspersed with lines of format control information and format the text into a printable, paginated document having a user-designed style. Troff and nroff offer unusual free- dom in document styling: arbitrary style headers and footers; arbitrary style footnotes; multiple automatic sequence numbering for paragraphs, sections, etc; multiple column output; dynamic font and point-size control; arbitrary horizontal and vertical local motions at any point; and a family of automatic overstriking, bracket construction, and line-drawing functions. Troff produces its output in a device-independent form, although parameterized for a specific device; troff output must be processed by a driver for that device to produce printed output. Troff and nroff are highly compatible with each other and it is almost always possible to prepare input acceptable to both. Conditional input is provided that enables the user to embed input expressly des- tined for either program. Nroff can prepare output directly for a variety of terminal types and is capable of utilizing the full resolution of each terminal. A warning, however: nroff necessarily cannot support all fea- tures of troff. -
Assembling a Prehistory for Formal Methods: a Personal View Thomas Haigh [email protected]
Assembling A Prehistory for Formal Methods: A Personal View Thomas Haigh [email protected] University of Wisconsin—Milwaukee & Siegen University www.tomandmaria.com This is a preprint copy. Please quote and cite the final version, which will appear in a special issue of Formal Aspects of Computing devoted to historical work. Thanks to Cliff Jones and the anonymous reviewers for their encouragement and feedback on earlier drafts of this paper. Preprint Draft Haigh – Assembling a History for Formal Methods 2 Although I was pleased to be asked to contribute something to this volume I have a confession to make: I have never studied the history of formal methods. So this is not going to be a history of formal methods as much as a reflection on how such a story might be written. My plan is to triangulate from my personal experiences as a computer science student a quarter century ago, my Ph.D. training as a historian of science and technology, and my subsequent career researching and writing about various aspects of the history of computing. The fact that, despite a general familiarity with the literature on the history of computing, I don’t have a better grasp of the history of formal methods tells us a lot about the need for this special issue. Most of the history is so far locked up in the heads of participants, which is not a convenient place for the rest of us to find it. Stories written by participants or people with a personal connection to the events described are not usually the last word on historical events, but they are a vital starting point.