Leslie Lamport
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Object Oriented Programming
No. 52 March-A pril'1990 $3.95 T H E M TEe H CAL J 0 URN A L COPIA Object Oriented Programming First it was BASIC, then it was structures, now it's objects. C++ afi<;ionados feel, of course, that objects are so powerful, so encompassing that anything could be so defined. I hope they're not placing bets, because if they are, money's no object. C++ 2.0 page 8 An objective view of the newest C++. Training A Neural Network Now that you have a neural network what do you do with it? Part two of a fascinating series. Debugging C page 21 Pointers Using MEM Keep C fro111 (C)rashing your system. An AT Keyboard Interface Use an AT keyboard with your latest project. And More ... Understanding Logic Families EPROM Programming Speeding Up Your AT Keyboard ((CHAOS MADE TO ORDER~ Explore the Magnificent and Infinite World of Fractals with FRAC LS™ AN ELECTRONIC KALEIDOSCOPE OF NATURES GEOMETRYTM With FracTools, you can modify and play with any of the included images, or easily create new ones by marking a region in an existing image or entering the coordinates directly. Filter out areas of the display, change colors in any area, and animate the fractal to create gorgeous and mesmerizing images. Special effects include Strobe, Kaleidoscope, Stained Glass, Horizontal, Vertical and Diagonal Panning, and Mouse Movies. The most spectacular application is the creation of self-running Slide Shows. Include any PCX file from any of the popular "paint" programs. FracTools also includes a Slide Show Programming Language, to bring a higher degree of control to your shows. -
Using the GNU Compiler Collection (GCC)
Using the GNU Compiler Collection (GCC) Using the GNU Compiler Collection by Richard M. Stallman and the GCC Developer Community Last updated 23 May 2004 for GCC 3.4.6 For GCC Version 3.4.6 Published by: GNU Press Website: www.gnupress.org a division of the General: [email protected] Free Software Foundation Orders: [email protected] 59 Temple Place Suite 330 Tel 617-542-5942 Boston, MA 02111-1307 USA Fax 617-542-2652 Last printed October 2003 for GCC 3.3.1. Printed copies are available for $45 each. Copyright c 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with the Invariant Sections being \GNU General Public License" and \Funding Free Software", the Front-Cover texts being (a) (see below), and with the Back-Cover Texts being (b) (see below). A copy of the license is included in the section entitled \GNU Free Documentation License". (a) The FSF's Front-Cover Text is: A GNU Manual (b) The FSF's Back-Cover Text is: You have freedom to copy and modify this GNU Manual, like GNU software. Copies published by the Free Software Foundation raise funds for GNU development. i Short Contents Introduction ...................................... 1 1 Programming Languages Supported by GCC ............ 3 2 Language Standards Supported by GCC ............... 5 3 GCC Command Options ......................... -
On-The-Fly Garbage Collection: an Exercise in Cooperation
8. HoIn, B.K.P. Determining lightness from an image. Comptr. Graphics and Image Processing 3, 4(Dec. 1974), 277-299. 9. Huffman, D.A. Impossible objects as nonsense sentences. In Machine Intelligence 6, B. Meltzer and D. Michie, Eds., Edinburgh U. Press, Edinburgh, 1971, pp. 295-323. 10. Mackworth, A.K. Consistency in networks of relations. Artif. Intell. 8, 1(1977), 99-118. I1. Marr, D. Simple memory: A theory for archicortex. Philos. Trans. Operating R.S. Gaines Roy. Soc. B. 252 (1971), 23-81. Systems Editor 12. Marr, D., and Poggio, T. Cooperative computation of stereo disparity. A.I. Memo 364, A.I. Lab., M.I.T., Cambridge, Mass., 1976. On-the-Fly Garbage 13. Minsky, M., and Papert, S. Perceptrons. M.I.T. Press, Cambridge, Mass., 1968. Collection: An Exercise in 14. Montanari, U. Networks of constraints: Fundamental properties and applications to picture processing. Inform. Sci. 7, 2(April 1974), Cooperation 95-132. 15. Rosenfeld, A., Hummel, R., and Zucker, S.W. Scene labelling by relaxation operations. IEEE Trans. Systems, Man, and Cybernetics Edsger W. Dijkstra SMC-6, 6(June 1976), 420-433. Burroughs Corporation 16. Sussman, G.J., and McDermott, D.V. From PLANNER to CONNIVER--a genetic approach. Proc. AFIPS 1972 FJCC, Vol. 41, AFIPS Press, Montvale, N.J., pp. 1171-1179. Leslie Lamport 17. Sussman, G.J., and Stallman, R.M. Forward reasoning and SRI International dependency-directed backtracking in a system for computer-aided circuit analysis. A.I. Memo 380, A.I. Lab., M.I.T., Cambridge, Mass., 1976. A.J. Martin, C.S. -
Arxiv:1909.05204V3 [Cs.DC] 6 Feb 2020
Cogsworth: Byzantine View Synchronization Oded Naor, Technion and Calibra Mathieu Baudet, Calibra Dahlia Malkhi, Calibra Alexander Spiegelman, VMware Research Most methods for Byzantine fault tolerance (BFT) in the partial synchrony setting divide the local state of the nodes into views, and the transition from one view to the next dictates a leader change. In order to provide liveness, all honest nodes need to stay in the same view for a sufficiently long time. This requires view synchronization, a requisite of BFT that we extract and formally define here. Existing approaches for Byzantine view synchronization incur quadratic communication (in n, the number of parties). A cascade of O(n) view changes may thus result in O(n3) communication complexity. This paper presents a new Byzantine view synchronization algorithm named Cogsworth, that has optimistically linear communication complexity and constant latency. Faced with benign failures, Cogsworth has expected linear communication and constant latency. The result here serves as an important step towards reaching solutions that have overall quadratic communication, the known lower bound on Byzantine fault tolerant consensus. Cogsworth is particularly useful for a family of BFT protocols that already exhibit linear communication under various circumstances, but suffer quadratic overhead due to view synchro- nization. 1. INTRODUCTION Logical synchronization is a requisite for progress to be made in asynchronous state machine repli- cation (SMR). Previous Byzantine fault tolerant (BFT) synchronization mechanisms incur quadratic message complexities, frequently dominating over the linear cost of the consensus cores of BFT so- lutions. In this work, we define the view synchronization problem and provide the first solution in the Byzantine setting, whose latency is bounded and communication cost is linear, under a broad set of scenarios. -
Seashore Guide
Seashore The Incomplete Guide Contents Contents..........................................................................................................................1 Introducing Seashore.......................................................................................................4 Product Summary........................................................................................................4 Technical Requirements ..............................................................................................4 Development Notice....................................................................................................4 Seashore’s Philosophy.................................................................................................4 Seashore and the GIMP...............................................................................................4 How do I contribute?...................................................................................................5 The Concepts ..................................................................................................................6 Bitmaps.......................................................................................................................6 Colours .......................................................................................................................7 Layers .........................................................................................................................7 Channels .................................................................................................................. -
Mathematical Writing by Donald E. Knuth, Tracy Larrabee, and Paul M
Mathematical Writing by Donald E. Knuth, Tracy Larrabee, and Paul M. Roberts This report is based on a course of the same name given at Stanford University during autumn quarter, 1987. Here's the catalog description: CS 209. Mathematical Writing|Issues of technical writing and the ef- fective presentation of mathematics and computer science. Preparation of theses, papers, books, and \literate" computer programs. A term paper on a topic of your choice; this paper may be used for credit in another course. The first three lectures were a \minicourse" that summarized the basics. About two hundred people attended those three sessions, which were devoted primarily to a discussion of the points in x1 of this report. An exercise (x2) and a suggested solution (x3) were also part of the minicourse. The remaining 28 lectures covered these and other issues in depth. We saw many examples of \before" and \after" from manuscripts in progress. We learned how to avoid excessive subscripts and superscripts. We discussed the documentation of algorithms, com- puter programs, and user manuals. We considered the process of refereeing and editing. We studied how to make effective diagrams and tables, and how to find appropriate quota- tions to spice up a text. Some of the material duplicated some of what would be discussed in writing classes offered by the English department, but the vast majority of the lectures were devoted to issues that are specific to mathematics and/or computer science. Guest lectures by Herb Wilf (University of Pennsylvania), Jeff Ullman (Stanford), Leslie Lamport (Digital Equipment Corporation), Nils Nilsson (Stanford), Mary-Claire van Leunen (Digital Equipment Corporation), Rosalie Stemer (San Francisco Chronicle), and Paul Halmos (University of Santa Clara), were a special highlight as each of these outstanding authors presented their own perspectives on the problems of mathematical communication. -
Verification and Specification of Concurrent Programs
Verification and Specification of Concurrent Programs Leslie Lamport 16 November 1993 To appear in the proceedings of a REX Workshop held in The Netherlands in June, 1993. Verification and Specification of Concurrent Programs Leslie Lamport Digital Equipment Corporation Systems Research Center Abstract. I explore the history of, and lessons learned from, eighteen years of assertional methods for specifying and verifying concurrent pro- grams. I then propose a Utopian future in which mathematics prevails. Keywords. Assertional methods, fairness, formal methods, mathemat- ics, Owicki-Gries method, temporal logic, TLA. Table of Contents 1 A Brief and Rather Biased History of State-Based Methods for Verifying Concurrent Systems .................. 2 1.1 From Floyd to Owicki and Gries, and Beyond ........... 2 1.2Temporal Logic ............................ 4 1.3 Unity ................................. 5 2 An Even Briefer and More Biased History of State-Based Specification Methods for Concurrent Systems ......... 6 2.1 Axiomatic Specifications ....................... 6 2.2 Operational Specifications ...................... 7 2.3 Finite-State Methods ........................ 8 3 What We Have Learned ........................ 8 3.1 Not Sequential vs. Concurrent, but Functional vs. Reactive ... 8 3.2Invariance Under Stuttering ..................... 8 3.3 The Definitions of Safety and Liveness ............... 9 3.4 Fairness is Machine Closure ..................... 10 3.5 Hiding is Existential Quantification ................ 10 3.6 Specification Methods that Don’t Work .............. 11 3.7 Specification Methods that Work for the Wrong Reason ..... 12 4 Other Methods ............................. 14 5 A Brief Advertisement for My Approach to State-Based Ver- ification and Specification of Concurrent Systems ....... 16 5.1 The Power of Formal Mathematics ................. 16 5.2Specifying Programs with Mathematical Formulas ........ 17 5.3 TLA ................................. -
The Specification Language TLA+
Leslie Lamport: The Speci¯cation Language TLA+ This is an addendum to a chapter by Stephan Merz in the book Logics of Speci¯cation Languages by Dines Bj¿rner and Martin C. Henson (Springer, 2008). It appeared in that book as part of a \reviews" chapter. Stephan Merz describes the TLA logic in great detail and provides about as good a description of TLA+ and how it can be used as is possible in a single chapter. Here, I give a historical account of how I developed TLA and TLA+ that explains some of the design choices, and I briefly discuss how TLA+ is used in practice. Whence TLA The logic TLA adds three things to the very simple temporal logic introduced into computer science by Pnueli [4]: ² Invariance under stuttering. ² Temporal existential quanti¯cation. ² Taking as atomic formulas not just state predicates but also action for- mulas. Here is what prompted these additions. When Pnueli ¯rst introduced temporal logic to computer science in the 1970s, it was clear to me that it provided the right logic for expressing the simple liveness properties of concurrent algorithms that were being considered at the time and for formalizing their proofs. In the early 1980s, interest turned from ad hoc properties of systems to complete speci¯cations. The idea of speci- fying a system as a conjunction of the temporal logic properties it should satisfy seemed quite attractive [5]. However, it soon became obvious that this approach does not work in practice. It is impossible to understand what a conjunction of individual properties actually speci¯es. -
Using Lamport Clocks to Reason About Relaxed Memory Models
Using Lamport Clocks to Reason About Relaxed Memory Models Anne E. Condon, Mark D. Hill, Manoj Plakal, Daniel J. Sorin Computer Sciences Department University of Wisconsin - Madison {condon,markhill,plakal,sorin}@cs.wisc.edu Abstract industrial product groups spend more time verifying their Cache coherence protocols of current shared-memory mul- system than actually designing and optimizing it. tiprocessors are difficult to verify. Our previous work pro- To verify a system, engineers should unambiguously posed an extension of Lamport’s logical clocks for showing define what “correct” means. For a shared-memory sys- that multiprocessors can implement sequential consistency tem, “correct” is defined by a memory consistency model. (SC) with an SGI Origin 2000-like directory protocol and a A memory consistency model defines for programmers the Sun Gigaplane-like split-transaction bus protocol. Many allowable behavior of hardware. A commonly-assumed commercial multiprocessors, however, implement more memory consistency model requires a shared-memory relaxed models, such as SPARC Total Store Order (TSO), a multiprocessor to appear to software as a multipro- variant of processor consistency, and Compaq (DEC) grammed uniprocessor. This model was formalized by Alpha, a variant of weak consistency. Lamport as sequential consistency (SC) [12]. Assume that This paper applies Lamport clocks to both a TSO and an each processor executes instructions and memory opera- Alpha implementation. Both implementations are based on tions in a dynamic execution order called program order. the same Sun Gigaplane-like split-transaction bus protocol An execution is SC if there exists a total order of memory we previously used, but the TSO implementation places a operations (reads and writes) in which (a) the program first-in-first-out write buffer between a processor and its orders of all processors are respected and (b) a read returns cache, while the Alpha implementation uses a coalescing the value of the last write (to the same address) in this write buffer. -
Using MATLAB
MATLAB® The Language of Technical Computing Computation Visualization Programming Using MATLAB Version 6 How to Contact The MathWorks: www.mathworks.com Web comp.soft-sys.matlab Newsgroup [email protected] Technical support [email protected] Product enhancement suggestions [email protected] Bug reports [email protected] Documentation error reports [email protected] Order status, license renewals, passcodes [email protected] Sales, pricing, and general information 508-647-7000 Phone 508-647-7001 Fax The MathWorks, Inc. Mail 3 Apple Hill Drive Natick, MA 01760-2098 For contact information about worldwide offices, see the MathWorks Web site. Using MATLAB COPYRIGHT 1984 - 2001 by The MathWorks, Inc. The software described in this document is furnished under a license agreement. The software may be used or copied only under the terms of the license agreement. No part of this manual may be photocopied or repro- duced in any form without prior written consent from The MathWorks, Inc. FEDERAL ACQUISITION: This provision applies to all acquisitions of the Program and Documentation by or for the federal government of the United States. By accepting delivery of the Program, the government hereby agrees that this software qualifies as "commercial" computer software within the meaning of FAR Part 12.212, DFARS Part 227.7202-1, DFARS Part 227.7202-3, DFARS Part 252.227-7013, and DFARS Part 252.227-7014. The terms and conditions of The MathWorks, Inc. Software License Agreement shall pertain to the government’s use and disclosure of the Program and Documentation, and shall supersede any conflicting contractual terms or conditions. If this license fails to meet the government’s minimum needs or is inconsistent in any respect with federal procurement law, the government agrees to return the Program and Documentation, unused, to MathWorks. -
Should Your Specification Language Be Typed?
Should Your Specification Language Be Typed? LESLIE LAMPORT Compaq and LAWRENCE C. PAULSON University of Cambridge Most specification languages have a type system. Type systems are hard to get right, and getting them wrong can lead to inconsistencies. Set theory can serve as the basis for a specification lan- guage without types. This possibility, which has been widely overlooked, offers many advantages. Untyped set theory is simple and is more flexible than any simple typed formalism. Polymorphism, overloading, and subtyping can make a type system more powerful, but at the cost of increased complexity, and such refinements can never attain the flexibility of having no types at all. Typed formalisms have advantages too, stemming from the power of mechanical type checking. While types serve little purpose in hand proofs, they do help with mechanized proofs. In the absence of verification, type checking can catch errors in specifications. It may be possible to have the best of both worlds by adding typing annotations to an untyped specification language. We consider only specification languages, not programming languages. Categories and Subject Descriptors: D.2.1 [Software Engineering]: Requirements/Specifica- tions; D.2.4 [Software Engineering]: Software/Program Verification—formal methods; F.3.1 [Logics and Meanings of Programs]: Specifying and Verifying and Reasoning about Pro- grams—specification techniques General Terms: Verification Additional Key Words and Phrases: Set theory, specification, types Editors’ introduction. We have invited the following -
GNU Guix: Package Without a Scheme!
GNU Guix: Package without a scheme! . Andreas Enge [email protected] GNU Hackers Meeting Paris, 23 August 2013 Andreas Enge (GNU Guix) GNU Guix packaging GHM 2013 1 Guix system Two chunks of code Guix package manager I inside guix/ I lots of Scheme GNU system I inside gnu/ I Bootable system (gnu/system/), not yet written I Packages (gnu/packages/), almost no Scheme! Andreas Enge (GNU Guix) GNU Guix packaging GHM 2013 2 Available packages guix package -A | wc 454 115 GNU packages (out of 364) GCC, 6 Schemes, Perl, Python, Ocaml TeX Live X.org (client side) Glib, Cairo, Pango, Gtk+ Only free software! As pristine as possible (minimal patches) http://www.gnu.org/software/guix/package-list.html Andreas Enge (GNU Guix) GNU Guix packaging GHM 2013 3 Package description name: Lower case original package name version source I uri: Possibility of mirror://xxx/... with xxx 2 gnu, sourceforge, savannah, cpan, kernel.org, gnome, apache, xorg, imagemagick I sha256: Hash of tarball I build-system: gnu-build-system, trivial-build-system, python-build-system, perl-build-system, cmake-build-system synopsis: As in GNU Womb, not repeating the package name description: Usually taken from web page, two spaces at end of sentence license; see guix/licenses.scm home-page Andreas Enge (GNU Guix) GNU Guix packaging GHM 2013 4 Guix architecture Courtesy of Ludovic Courtès Build processes chroot, separate UID User tools guix build. guix package guix gc . make, gcc, … make, gcc, … make, gcc, … RPC Nix build daemon . sudo guix-daemon . --build-users-group=guix-builder