See also Free On-line Dictionary of Computing
The New Hacker's Dictionary (The Jargon File)
See also BABEL: A Glossary of Computer Related Abbreviations and Acronyms at http://www.access.digex.net/~ikind/babel.html.
See also the Glossary of Internet Terms at http://www.matisse.net/files/glossary.html and Glossary by the User Glossary Working Group of the IETF at ftp://nic.merit.edu/documents/fyi/fyi_18.txt
See also a glossary of Ada Terms in the Ada reference manual at http://lglwww.epfl.ch/Ada/LRM/9X/rm9x/rm9x-N.html.
See also a glossary of Java Terms at http://java.sun.com/glossary.html.
L. G. Valiant. The complexity of enumeration and reliability problems. SIAM J. Comput., 8:410-421, 1979.
A | B | C | D | E | F | G | H | I | J | K | L | M |
N | O | P | Q | R | S | T | U | V | W | X | Y | Z |
A map represents certain geographic features like the distance between features. Other details are regarded as irrelevant like the color of the terrain. The areial photo of Marienplatz in Munich does not make a convenient map of the area because it has too much detail. A subway map is a further level of abstraction as it shows the topographical relationships with repect to the subway lines. Even distance (to scale) is disregarded.
See also:
abstract data type (q.v.),
encapsulation (q.v.),
procedural abstraction, and data abstraction.
In the object-oriented programming languages C++ and Java, an access specifier modifies a class, a method, or a variable and determines which other parts of the program may access it.
In order for two hosts to communicate, the logical IP address must resolve to the physical address of the network adapter card. ARP is the protocol that resolves IP addresses to physical addresses. It is defined in RFC 826.
A program specifies in the exact syntax of some programming language the computation one expects a computer to perform. The syntax is precise and unforgiving. The slightest error in the program as written may cause the computation to be in error or may halt it altogether. The reason for this situation seems paradoxical on the surface: It is relatively easy to design a system that converts rigid syntax to computations; it is much harder to design a system that tolerates mistakes or accepts a broader range of program descriptions.
An algorithm may specify essentially the same computation as a specific program written in a specific language such as BASIC, Pascal, or C. Yet, the purpose of an algorithm is to communicate a computation not to computers but to humans. This is a more natural state of affairs than most people suppose. Our lives (whether we work with computers or not) are full of algorithms. A recipe, for example, is an algorithm for preparing food (assuming, for the moment, that we think of cooking as a form of computation).
constant | O(1) |
logarithmic | O(log n) |
linear | O(n) |
polynomial | O(nk) k>0 |
exponential | O(kn) k>1 |
A Java program that runs inside a WWW Browser. These programs are attached to a larger document and hence the term applet for a small application program.
An international organization of computing professionals dedicated to promoting information technology through education, publications, conferences, etc. The ACM was founded 1947 and is headquartered in New York City.
Assembly code is a programming language that is a mnemonic version of machine code with symbolic names for memory addresses. Assembly code can be written directly by programmers or it can be procedure by other programs, for example, compilers (q.v.). An assembler translates the assembly code to machine code often allowing additional constructs in the input, like macros.
A | B | C | D | E | F | G | H | I | J | K | L | M |
N | O | P | Q | R | S | T | U | V | W | X | Y | Z |
In midst of problems in the project to build the Difference Engine, Babbage tried in 1834 to build a new machine--the Analytical Engine--capable of any mathematical operation. But the English government was skeptical and the device was never built.
Charles Babbage, Pioneer of the Computer by Anthony Hyman, Oxford University Press, 1982.
Irascible Genius by Moseley Maboth, Hutchinson & Co., London, 1964.
uuencode uses the space character making the spaces significant. Some mail software deletes trailing spaces.
addr+3 | 4F |
addr+2 | 7B |
addr+1 | 56 |
addr+0 | 2D |
addr+3 | 56 |
addr+2 | 2D |
addr+1 | 7B |
addr+0 | 4F |
symbol | Pascal, SML | Modula-3 | Ada | C, C++, Java |
---|---|---|---|---|
< | < | < | < | < |
![]() |
<= | <= | <= | <= |
> | > | > | > | > |
![]() |
>= | >= | >= | >= |
= | = | = | = | == |
![]() |
<> | # | /= | != |
+ | + | + | + | + |
- | - | - | - | - |
× | * | * | * | * |
div | div | div | / | / |
mod | mod | mod | mod | % |
The term "bit" first appeared in print in the computer-science sense in 1949, and seems to have been coined by early computer scientist John Tukey. Tukey records that it evolved over a lunch table as a handier alternative to "bigit" or "binit". [From the FOLDC.]
A data file or structure in which each black or white pixel (q.v.) of the image is represented by a bit, just as the video memory of some display devices. A color image could be represented by encoding each color using several bits.
A computer output device where each pixel (q.v.) that is displayed corresponds directly to one or more bits in the computer's video memory. Early output devices were capable of displaying only one of a few characters in each rectangular region of the display. Most modern personal computers and workstations have bitmap displays, enabling the display of lines, circles, special effects like shading, and multiple character sets.
For example,
<expression> ::= <identifier> | <number> | <expression> + <expression>This defines an expression to be either an identifier or a number or an expression followed by a plus sign followed by an expression. Thus, the following are expresssions:
x 2 x+2 x+y+3and these are not (by this particular BNF definition):
x,y 2x x-y+3 )x#2
BNF definitions define a set of strings in a formal language (q.v.). These sets (called syntactic categories (q.v.)) may be simultaneously defined with several clauses of the form
The meta-language (q.v.) of BNF includes the symbol "::=" to mean "is defined to be" and the symbol "|" to mean "or". Often the BNF meta-language is extended to include the notation "[ ]" to mean "optional" and "{ }" to mean "zero, one, or more times".
an error in a computer program. From the Jargon File, version 4.0.0, July 25, 1996:
Admiral Grace Hopper (an early computing pioneer better known for inventing COBOL) liked to tell a story in which a technician solved a glitch in the Harvard Mark II machine by pulling an actual insect out from between the contacts of one of its relays, and she subsequently promulgated bug in its hackish sense as a joke about the incident (though, as she was careful to admit, she was not there when it happened). For many years the logbook associated with the incident and the actual bug in question (a moth) sat in a display case at the Naval Surface Warfare Center (NSWC). The entire story, with a picture of the logbook and the moth taped into it, is recorded in the "Annals of the History of Computing", Vol. 3, No. 3 (July 1981), pp. 285--286.
The text of the log entry (from September 9, 1947), reads "1545 Relay #70 Panel F (moth) in relay. First actual case of bug being found". This wording establishes that the term was already in use at the time in its current specific sense -- and Hopper herself reports that the term `bug' was regularly applied to problems in radar electronics during WWII.
Indeed, the use of `bug' to mean an industrial defect was already established in Thomas Edison's time, and a more specific and rather modern use can be found in an electrical handbook from 1896 ("Hawkin's New Catechism of Electricity", Theo. Audel & Co.) which says: "The term `bug' is used to a limited extent to designate any fault or trouble in the connections or working of electric apparatus." It further notes that the term is "said to have originated in quadruplex telegraphy and have been transferred to all electric apparatus."
The latter observation may explain a common folk etymology of the term; that it came from telephone company usage, in which "bugs in a telephone cable" were blamed for noisy lines. Though this derivation seems to be mistaken, it may well be a distorted memory of a joke first current among telegraph operators more than a century ago!
Or perhaps not a joke. Historians of the field inform us that the term "bug" was regularly used in the early days of telegraphy to refer to a variety of semi-automatic telegraphy keyers that would send a string of dots if you held them down. In fact, the Vibroplex keyers (which were among the most common of this type) even had a graphic of a beetle on them! While the ability to send repeated dots automatically was very useful for professional morse code operators, these were also significantly trickier to use than the older manual keyers, and it could take some practice to ensure one didn't introduce extraneous dots into the code by holding the key down a fraction too long. In the hands of an inexperienced operator, a Vibroplex "bug" on the line could mean that a lot of garbled Morse would soon be coming your way.
Actually, use of `bug' in the general sense of a disruptive event goes back to Shakespeare! In the first edition of Samuel Johnson's dictionary one meaning of `bug' is "A frightful object; a walking spectre"; this is traced to `bugbear', a Welsh term for a variety of mythological monster which (to complete the circle) has recently been reintroduced into the popular lexicon through fantasy role-playing games.
A | B | C | D | E | F | G | H | I | J | K | L | M |
N | O | P | Q | R | S | T | U | V | W | X | Y | Z |
Term used in the LISP 1.5 Programmer's Manual, 1965, page 46, to describe the representation of propositional formulas as S-expressions, ie., (operator operand operand), for Wang's algorithm for tautology checking. Presumably in reference to Lukasiewicz' parentheses free notation for logic.
Formed by DARPA after the Morris worm incident in 1988. Located at the SEI of CMU.
V.1-V.7 General V.10-V.34 Interfaces and voice-band modems V.35-V.37 Wideband modems V.40-V.42 Error control V.50-V.57 Transmission quality and maintenance V.100-V.230 Interworking with other networksFor example, v.32bis is a stardard for modems running at 14400 bps, with automatic fallback to 12000, 9600, 7200 and 4800. The "bis" indicates a second version of the standard.
Now called ITU.
The part of the computer that executes the instructions stored in memory; consists of the arithmetic/logic unit (q.v.) that performs operations, and the control unit that decodes the instructions and picks the next step.
Complexity has and will maintain a strong fascination for many people. It is true that we live in a complex world and strive to solve inherently complex problems, which often do require complex mechansims. However, this should not diminish our desire for elegant solutions, which convince by their clarity and effectiveness. Simple, elegant solutions are more effective, but they are harder to find than complex onces, and they require more time, whcih we often believe to be unaffordable.Niklaus Wirth, Turing Award lecture, 1984.
Complexity results from misdirected effort as well as lack of effort.
There are two way of constructing a software design: One way is to make it so simple that there are obviously no deficiencies; and the other way is to make it so complicated that there are no obvious deficiencies.Charles Anthony Richard Hoare
You know that I write slowly. This is chiefly because I am never satisfied until I have said as much as possible in a few words, and writing briefly takes far more time than writing at length.Karl Friedrich Gauss (1777-1855)
a collection of computers that can exchange information
If the computer may actually (or apparently) execute instructions simulatenously, then it is possible for a program to simultaneously control different streams of actions. In this context, these streams of actions are often called threads.
"An early network that offered e-mail and Internet connections to Computer Science Departments in colleges and universities. Initially funded by the National Science Foundation, CSNET later became self-sufficient." Comer, The Internet Book.
A term coined by William Gibson in his 1984 science fiction novel Neuromancer meaning an alternate reality created by computers that takes the place of the universe perceived by the naked senses (cf. virtual reality). More generally it refers to the area of social interaction conducted with the aid of telecommunications and the information accessible by computers.
A | B | C | D | E | F | G | H | I | J | K | L | M |
N | O | P | Q | R | S | T | U | V | W | X | Y | Z |
declare X: Integer; -- a declaration introducing "X" begin X := 45*89; -- an executable statement using "X" end;
Type names, exception names, subprocedure and function names, etc are all introduced by declarations in most programming languages.
a user interface in which the operands are represented visually, and operations are invoked by manipulating the representations using a mouse; in contrast to a command oriented user interface. For example, dragging an icon for a particular file to a picture of a trashcan on the screen. Ben Shneiderman coined the phrase "direct manipulation."
A | B | C | D | E | F | G | H | I | J | K | L | M |
N | O | P | Q | R | S | T | U | V | W | X | Y | Z |
A format for executable and object files on UNIX systems. Gradually replacing the a.out format.
The ENIAC (Electronic Numerical Integrator And Computer) was designed at the Moore School of Electrical Engineering (Univeristy of Pennslyvania) by John W. Mauchley and J. Presper Eckert Jr. It is widely accepted as the world's first operational electronic general-purpose computer. Construction began in 1943. It contains 18,000 vacuum tubes and 1,500 relays, weighed 30 tons and had twenty 10-digit registers. It ran at a speed of fourteen 10-digit multiplications per second or 5,000 additions per second. It was programmed by setting 6,000 multiposition switches and connecting a multitude of sockets with jumper cables. It was first publicly demonstrated 14 February 1946 and was in use until 1955.
Lt. Herman Goldstine of the Ballistics Research Laboratory in Maryland encouraged the project to build a device to compute ballistic tables. An official proposal was submitted in April of 1943. The U.S. Army, Ordnance Department provided approximately $500,000 for the ENIAC's development.
Incorporated in 1990, EIT was founded by Jay M. Tenenbaum and three colleagues from Schlumberger Technologies. EIT is located in Menlo Park, California and offers WWW services and technologies, e.g., Secure HTTP (q.v.). In November 1995, EIT was acquired by VeriFone, Inc. and now operates as a wholly owned subsidiary, developing products for VeriFone's Internet Commerce Division.
Invented by Bob Metcalfe.
Uncaught exception "X" raised at line "123" of "main.pl"Sometime even a complete dump of the runtime stack at the point the execption occurred may be provided. Keeping the runtime information in order to report these details does entail some cost. So some systems, may only report the name of the exception that was raised.
PROCEDURE Exp (base: REAL; power: REAL): REAL = (* Modula-3 *) fun Exp (base: real, power: real): real = (* ML *) procedure Exp (base: Float; power: Float) return Float is -- AdaThe formal parameters are base and power.
A WWW site of Earthweb containing hundreds of Java applets (q.v.). A gamelan is a Javanese instrument resembling a xylophone or a kind of orchestra of southeast Asia.
William H. (Bill) Gates is chairman and chief executive officer of Microsoft Corporation, the leading provider of software for personal computers worldwide. Gates began his career in personal computer software when he started programming at age 13. In 1974, while an undergraduate at Harvard University, he developed BASIC for the first microcomputer, the MITS Altair. Led by the belief that the personal computer would ultimately be a valuable tool on every office desktop and in every home, Gates formed Microsoft with Paul Allen in 1975 to develop software for personal computers. -- from Microsoft Corportate InfoAuthor of the The Road Ahead. A biography can be found in Portraits in Silicon.
Garbage collection is the service in which the operating system systematically detects that a program no longer needs some portion of the memory allocated to it and reclaims the unneeded portion. The reclaimed portion can then be allocated to some other program or even reallocated to the original program if it requests more memory.
Links to archives of GNU software can be found at the Unofficial GNU WWW site.
In 1972 Hewlett Packard introduced the HP-35 calculator for $395. The calculator performed transcendental functions and employed reverse Polish notation (RPN).
She helped develop the Flow-Matic programming language in 1957 for the Mark series of computers at Harvard Univeristy and the Common Business-Oriented Language (COBOL) in 1959-1961 for the UNIVAC. Prompted to the rank of Rear Admiral in 1983.
Literary machines: The report on, and of, Project Xanadu concerning word processing, electronic publishing, hypertext, thinkertoys, tomorrow's intellectual revolution, and certain other topics including knowledge, education and freedomwhere he defined it as "non-sequential writing."
A series of four computers developed at the University of Illinois. The first, ILLIAC I, a vacuum-tube machine completed in 1952 performed 11,000 arithmetical operations per second.
"Initial Design for Interface Message Processors for the ARPA Computer Network," BBN Report No. 1763, January 6, 1969.
UC Berkeley professor, Dr. Eric Brewer and graduate student Paul Gauthier founded Inktomi Corporation in February 1996. Wired Ventures, Inc. and Inktomi teamed to build HotBot search engine in May 1996. On May 18, 1998 it was announced that Inktomi and Yahoo! have entered an agreement giving Yahoo! the right to make Inktomi an integrated Yahoo! search results provider. Under the agreement, Inktomi will provide the underlying Web search engine to complement Yahoo!'s popular Web directory and navigational guide.
"INK-to-me," is derived from a Lakota Indian legend about a trickster spider character. Inktomi is known for his ability to defeat larger adversaries through wit and cunning.
An organization that coordinates national standards along with the International Organization for Standardization (ISO) (q.v.) An agreement in 1976 gives the IEC responsiblity for standards in the area of electrical and electronic engineering and the ISO everything else.
A non-governmental organization established in 1947 as a federation of national standard bodies, one from each of some 100 countries. The organization is known as ISO (q.v.) for short.
An IMAP client program on any platform at any location on the Internet can access email folders on an IMAP server. While the messages appear to be local, they reside on the server until the client explicitly moves or deletes them. The IMAP protocol is a superset of POP, containing all POP commands plus more. For a comparison of IMAP and POP, see the paper Comparing Two Approaches to Remote Mailbox Access: IMAP vs. POP (in ftp.cac.washington.edu:/mail/imap.vs.pop). IMAP is what allows Pine (or any other IMAP client) to get to email on a central campus email server. There are current IETF working groups revising IMAP and readying it to become an Internet standard. A copy of the latest IMAP draft may be obtained from ftp://ftp.cac.washington.edu/mail/latest-imap-draft. For a list of IMAP clients, see the file imap.software, in the same directory.
ISBN 0 17 006737 8 ISBN 0 949155 09 8 ISBN 1 86252 140 9In the examples above 0 or 1 represent the group identifier, based on national, geographic or language considerations. The second part of the number (17, 949155, and 86252 in the example above) is the publisher identifier and designates a particular publisher or group of publishers. The third part of the number (006737, 09, and 140) is the title identifier assigned to a particular title or edition of a title. The final digit is a computer check digit. The check digit is calculated from the preceding nine digits and is used by computers to trap errors made in the writing or keying of the ISBN number.
Many people will have noticed a seeming lack of correspondence between the official title when used in full, International Organization for Standardization, and the short form, ISO. Shouldn't the acronym be "IOS"? Yes, if it were an acronym -- which it is not.from Introduction to ISOIn fact, "ISO" is a word, derived from the Greek isos, meaning "equal", which is the root of the prefix "iso-" that occurs in a host of terms, such as "isometric" (of equal measure or dimensions -- Shorter Oxford English Dictionary) and "isonomy (equality of laws, or of people before the law -- ibid.).
From "equal" to "standard", the line of thinking that led to the choice of "ISO" as the name of the organization is easy to follow.
In addition, the name has the advantage of being valid in each of the organization's three official languages -- English, French and Russian. The confusion that would arise through the use of an acronym is thus avoided, e.g. "IOS" would not correspond to the official title of the organization in French -- Organisation internationale de normalisation.
The International Telecommunication Union (ITU) was founded in 1865 and is headquartered in Geneva, Switzerland In 1947, it became an agency of the United Nations and has a membership of 184 countries, as well as a number of industry and government organizations. Its purpose is the coordinating, regulating, and standardizing of telecommunications.
\ x1 ... \ xn . E --> (\ y1 ... \ yk . \ x1 ... \xn . E) y1 ... yk
\ x . x (\ y . x y) --> \ x . x (( \ x \y . x y ) x)
A broad definition for a broad conceptSee also formal language, syntax, semantics, meta-language, and object language.
Sometimes linking is done while the program is executing, this is called dynamic linking.
An NPR news report on Linux OS (requires RealAudio).
The significance an invariant lies in the fact that a program cannot be fully understood by mentally executing. The number of states is too large for the human mind to comprehend. Only by representing the execution of a program, in particular loops, with a nonchanging relationship among the program variables is it possible to understand and to write correct programs. Even though the values of the variables change, the meaningful relationships can be found, it is these relationships that are invariant.
Appendix E -- IANA Registration Procedures
MIME has been carefully designed to have extensible mechanisms, and it is expected that the set of content-type/subtype pairs and their associated parameters will grow significantly with time. Several other MIME fields, notably character set names, access-type parameters for the message/external-body type, and possibly even Content-Transfer-Encoding values, are likely to have new values defined over time. In order to ensure that the set of such values is developed in an orderly, well-specified, and public manner, MIME defines a registration process which uses the Internet Assigned Numbers Authority (IANA) as a central registry for such values.
See the media types registered at IANA.
History of matrices and determinants
The meta-language is the language used to communicate about or dicuss another language (called the object language (q.v.)).
For example, suppose an entity has header fields such as:
Content-Type: text/plain; charset=ISO-8859-1 Content-transfer-encoding: base64This is interpreted to mean that the body is a base64 ASCII encoding of data that was originally in Latin-1 character set (q.v.) (ISO 8859-1).
Modula-3 INTERFACE M; ... END M. MODULE M; ... BEGIN ... END M. Ada package P is ... end P; package body P is ... begin ... end P; SML signature SIG = sig ... end structure S: SIG = struct ... end Java package P; ...In Java there are no explicit specification files. Rather each element of the package is declared to be public (exportable) or private (not visible by a user of the package).
The Netscape specific URL about:mozilla shows the company mascot.
has a state which may be modified by certain operations without changing the identity of the objectLiskov, et al. CACM, vol 20, no 8, 1977, pages 564-576. For example, an array or a record is usually a mutable object. The subcomponents may be changed by assignment A[i]:=3 or r.f:=3, but the array A and r don't change their identity.
Here is an example of nested nonprocedural blocks in Ada (q.v.).
declare X: Integer; begin X := 1; -- Y is NOT visible here declare Y : Integer; begin Y := X; -- X and Y visible here end; X := 2; -- Y is NOT visible here either end;
NFS continues to fund the new architecture called the very high speed Backbone Network Services (vBNS) (q.v.) and provided by MCI. The four NSF-awarded Network Access Points (NAPs), provided by Ameritech, PacBell, Sprint, and MFS Datanet The NSF-funded Routing Arbiter project, which provides routing coordination in the new environment. The RA project is a partnership between Merit Network, Inc.; the University of Southern California Information Sciences Institute; IBM Corporation, as a subcontractor to ISI; and the University of Michigan ROC, as a subcontractor to Merit.
A convenient notation for dealing with approximations used for comparing functions of one variable by their rate of growth, i.e., an O(N2) function (quadratic) grows faster than a O(N) function (linear). Algorithms can be ranked by the functions that relate the number of steps the algorithm takes with the size of the problem. See "Time and Space Complexity" in The Turing Omnibus by Dewdney. The notation was introduced by Paul Gustav Heinrich Bachmann (1837-1920) in the book Analytische Zahlentheoreie in 1892.
The function f(n) is said to be O(g(n)) if there is an integer N and a constant C such that f(n) < C × g(n) for all n > N
See Headinton and Riley, Data Abstraction and Structures Using C++, Sections 12.1, 12.2 and 12.3.
A specification of software components promoted by Microsoft.
Founder of Digital Equipment Corporation (q.v.) in August 1957.
Few people recall what the acronym PCMCIA actually stands for, hence the it is often said to stand for People Can't Remember Computer-Industry Acronyms.
A general-purpose computer generally used by one person at a time for home and business applications. The concept was ursurped early on by IBM, but now PCs are mostly closely associated with the software giant Microsoft and the integrated circuit manufacturer INTEL.
One of his Epigrams on Programming:
The best book on programming for the layman is ``Alice in Wonderland''; but that's because it's the best book on anything for the layman.
A set of IEEE operating system interface standards for process, file, and directory management. IEEE 1003.1 defines a Unix-like operating system interface, 1003.2 the shell and utilities, and 1003.4 real-time extensions
FTP (data connection) 20 FTP (control connection) 21 telnet 23 smtp 25 who is 43 login 49 domain name server 53 gopher 70 finger 79 http (WWW protocol) 80 nntp 119 Z39.50 (WAIS protocol) 210cf. port numbers. Numbers less than 1024 are privileged. On some computer systems the file /etc/services lists which network services are assigned to which ports.
Mountain View, CA: December 11, 1995 - PostModern Computing today announced an object request broker, code-named Black Widow, which connects CORBA objects with the World Wide Web. With Black Widow, applets developed using Java can be used from web browsers such as Netscape and Spyglass to communicate with CORBA server objects implemented in Java or C++.from press release. Black Widow is expected to be available in the first quarter of 1996.
fun fact (n) = if n=0 then 1 else n*fact(n-1)assumes that the argument is non-negative.
See also postcondition, Hoare logic, weakest precondition calculus.
The representation of a procedure or function value at runtime. A procedure clousure is necessary in passing subprograms as arguments (to other procedures) and returning subprograms from functions. A procedure closure is a pair, a code pointer and an environment pointer. The environment pointer, or static link, is necessary to access the non-local environment.
Programming to solve large complex problems often with many programmers working together. The term was coined in the article "Programming-in-the-Large Versus Programming-in-the-Small," F. DeRemer and H. Kron, IEEE Transactions on Software Engineering, volume 2, number 2, June, 1976.
The opposite of programming-in-the-large (q.v.).
A programming language based on the resolution principle, a single rule of inference for first-order predicate logic. PROLOG was conceived and implemented in 1972 by Alain Colmerauer and Phillipe Roussel of the University of Marselles as part of a project in natural langauge translation. PROLOG is the primary example of logic programming.
The meaning of a sentence must remain unchanged when a part of the sentence is replaced by an expression having the same meaning.The phrase ``referential transparency'' was first used by Whitehead and Russell in Principia Mathematica to compare the following syllogisms:
All men are mortal;and
Socrates is a man;
Therefore Socrates is mortal.
Everything Xenophon said about Socrates is true;Quine talks about it in Section 30: Referential Opacity of Word and Object.
Xenophon said: ``Socrates is mortal'';
So Socrates is mortal.
In Ada the runtime system checks that subtype constraints are not violated, searches for exception handlers, allocates storage from the heap, controls interaction between tasks.
We cut nature up, organize it into concepts, and ascribe significances as we do, largely because we are parties to an agreement to organize it in this way--an agreement that holds throughout our speech community and is codified in patterns of our languages. The agreement is, of course, an implicit and unstated one, but its terms are absolutely obligatory; we cannot talk at all except by subscribing to the organization and classification of data which the agreement decrees.from Language Thought and Reality: Selected Writings of Benjamin Lee Whorf, MIT Press, 1956.
Although intuitively plausible, the hypothesis is controversial and the evidence he cited (lack of future tense in the language of the Hopi indians, multitude of words for snow in Inuit) has been discredited, see (for example) The Warp Factor. Nonetheless, programmers that have experience in imperative, functional, logic, and object-oriented programming ought to be better than those that more limited experience. The value of good mathematical notation seems obvious. Take for example multiplying in Roman numerals.
Sather is an object oriented language designed to be simple, efficient, safe, flexible and non-proprietary. ... Sather has parameterized classes, object-oriented dispatch, statically-checked strong (contravariant) typing, separate implementation and type inheritance, multiple inheritance, garbage collection, iteration abstraction, higher-order routines and iters, exception handling, assertions, preconditions, postconditions, and class invariants. Sather programs can be compiled into portable C code and can efficiently link with C object files.
A security-enhanced version of HTTP developed by Enterprise Integration Technologies, RSA Data Security, Inc., and the National Center for Supercomputing Applications. S-HTTP provides for transaction confidentiality, authentication, message integrity and non-repudiability of origin. A draft definition appears in The Secure HyperText Transfer Protocol, December 1994.
As the term comes into widespread use, it is identical to sending "junk" mail or even just "advertising."
subprogram-specification is separate ;or a package body stub
package body subprogram-specification is separate ;in the program. The bodies are found in separate files which can be given to the compiler and compiled without necessarily requiring the parent to be recompiled.
The subunit is not independent of the parent unit and, so, is not a library unit. Thus a subunit is never mentioned in a with clause.
A subunit may use declarations in the parent unit precisely as if the body were inserted at the place of the stub. A subunit begins with an optional context clause, followed by
separate ( parent-unit-name )followed by a subprogram or package body. (The separate clause is not follwed by a semicolon.)
The GNAT Ada compiler requires that the name of the subunit be formed like this:
parent-unit-name-subunit-name.adbusing the name of the parent unit and the subunit separated by a dash.
To convert a GIF image to a transparent GIF image you can use the PBM software, as in
giftopnm GIF87a-file | ppmtogif -trans color > GIF89a-filewhere color can be an RGB triple #CFCFCF or a name in the X Window System color database.
A system used in most computers to represent negative numbers in binary. Each bit of the number is inverted (zeros are replaced with ones and vice versa), as for ones complement, but then one (000...0001) is added (ignoring overflow). This avoids the two representations for zero found in ones complement by using all ones to represent -1.... -1 = 111...11111 000...00011 = +3 -2 = 111...11110 000...00010 = +2 ... 000...00001 = +1 100...00001 000...00000 = 0 100...00000 111...11111 = -1 011...11111 111...11110 = -2 ... 111...11101 = -3 +1 = 000...00001 = 1 ... 0 = 000...00000 = 0This representation simplifies the logic required for addition and subtraction, at the expense of a little extra complexity for negation.
The same internal representation (bits) can mean different things. Take, for example, the 32 bits
0xFF439EB2 = 1111 1111 0100 0011 1001 1110 1011 0010These bits could mean three different values depending on the interpretation.
-12345678 [ twos complement ] 4282621618 [ unsigned integer ] -2.6002345E38 [ IEEE 754 floating point ] ÿ# ² [ four Latin-1 characters ]
If the language permits the misinterpretation of data then the program outcome depends on the choice of internal representation which would be a very bad.
Types give an interpretation of data. If the language is designed so that the compiler knows the interpretation of all data, then the type of the value does not need to be keep with the data at all. Futhermore, no runtime checks would be necessary to prevent the data from being misinterpreted by an operation. Such languages are called strongly typed.
ISO-10646
An interactive, time-sharing operating system invented in 1969 by
Ken Thompson and Dennis Richie at AT&T Bell Labs for the PDP-7.
The name is not an acronym, but suggests the earlier
Multics project.
The Unix operation system has evolved and has been implemented
on a wide number of computer systems.
Versions inlcude Version 7, BSD, USG
Unix, Xenix, Ultrix, HPUX, AIX.
For his work on
the Unix project, William Joy won the Grace Murray Hopper Award in 1986.
Here is an example of the encoding with the octets in hex.
fun length (l) = if null l then 0 else 1 + length (tl l)
applies to lists of all types.
As opposed to ad hoc polymorphism (q.v.)
in which the same function name can refer to functions applicable to
a small number of different types.
See Cardelli and Wegner.
UCS-4 UTF-16 UTF-8
0000 0001; 0001; 01;
0000 007F; 007F; 7F;
0000 0080; 0080; C2; 80;
0000 07FF; 07FF; DF; BF;
0000 0800; 0800; E0; A0; 80;
0000 FFFF; FFFF; EF; BF; BF;
0001 0000; D800; DC00; F0; 90; 80; 80;
0010 FFFF; DBFF; DFFF; F4; 8F; BF; BF;
001F FFFF; FFFD; F7; BF; BF; BF;
0020 0000; FFFD; F8; 88; 80; 80; 80;
03FF FFFF; FFFD; FB; BF; BF; BF; BF;
0400 0000; FFFD; FC; 84; 80; 80; 80; 80;
7FFF FFFF; FFFD; FD; BF; BF; BF; BF; BF;
The vBNS uses the Internet Protocol (IP) over Asynchronous Transfer Mode (ATM) and Synchronous Optical Network (SONET) with network speeds at 155 Mbps and eventually 622 Mbps.
The vBNS connects the five HPCC centers and will be accessible to other networks through four network access points in New York, San Francisco, Chicago and Washington, D.C. (cf the network map).
child prodigy, mathematician, involved with the Los Alamos National Laboratory (and the Manhattan Project) and the Institute for Advanced Studies (IAS). He is credited with conceiving the notion of the stored-program computer.
In 1944, John von Neumann was attracted to the ENIAC [q.v.] project. The group wanted to improve the way programs were entered and discussed storing programs as numbers; von Neumann helped crystallize the ideas and wrote a memo proposing a stored-program computer called EDVAC (Electronic Discrecte Variable Automatic Computer) [q.v.]. Herman Goldstine distributed the memo and put von Neumann's name on it, much to the dismay of Eckert and Mauchly, whose names were omitted. This memo has served as the basis for the commonly used term von Neumann computer.From Hennessy and Patterson, Computer Organization.
X Consortium, Inc. is a not-for-profit consortium of sixty members worldwide. Founded in 1993 as the successor to the MIT X Consortium, it developed user interface standards and graphics technology. It is headquartered in Cambridge, Massachusetts.
In 1995, the X Consortium was named contractor for the next release of CDE and Motif. In 1996 it announced that responsibility for the X Window System would be transfered to The Open Group.
A platform-independent windowing system developed as part of the Athena project at MIT and later under the auspices of the X Consortium In March 1996 the X Consortium released the final version of X11, version 6.1. The X Window System is evolving into Broadway, an initiative for creating and accessing interactive applications in the World Wide Web.
a program capable of playing AVI, FLI, MOV, and MPEG movies on most common UNIX platforms including Linux.
A kind of socket for integrated circuits. A ZIF socket can be opened and closed by means of a lever or screw. When open, there the chip may be placed in the socket without any pressure at all, the socket is then closed, causing its contacts to grip the pins of the chip. Such sockets are used where chips must be inserted and removed frequently, such as in test equipment. They are more expensive and usually take up more space than conventional IC sockets.From FOLDOC.