## ZEBRA

A data management package in the CERN Program Library.

### Nearby terms:

za ♦ ZAP ♦ zap ♦ ZAPP ♦ Z-buffer ♦ **ZEBRA** ♦ Zed ♦ Zen ♦ zen ♦ ZENO ♦ zepto ♦ Zermelo Fränkel set theory

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## Zed

1978. Software Portability Group, U Waterloo. Eh, with types added. Similar to C. Implementation language for the Thoth realtime operating system. Added a few simple types for greater efficiency on byte-addressed machines. String constants in case statements. Enforces the naming convention: MANIFESTS, Externals and locals. "Porting the Zed Compiler", G.B. Bonkowski et al, SIGPLAN Notices 14(8):92-97 (Aug 1979).

### Nearby terms:

zap ♦ ZAPP ♦ Z-buffer ♦ ZEBRA ♦ **Zed** ♦ Zen ♦ zen ♦ ZENO ♦ zepto ♦ Zermelo Fränkel set theory

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## Zen

[Kehoe, B., "Zen and the Art of the Internet", February 1992.]

### Nearby terms:

Z-buffer ♦ ZEBRA ♦ Zed ♦ **Zen** ♦ zen ♦ ZENO ♦ zepto ♦ Zermelo Fränkel set theory

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## zen

<*jargon*>

To figure out something by meditation or by a sudden flash of enlightenment. Originally applied to bugs, but occasionally applied to problems of life in general. "How'd you figure out the buffer allocation problem?" "Oh, I zenned it."

Contrast grok, which connotes a time-extended version of zenning a system. Compare hack mode. See also guru.

Last updated: 1996-09-17

### Nearby terms:

ZEBRA ♦ Zed ♦ Zen ♦ **zen** ♦ ZENO ♦ zepto ♦ Zermelo Fränkel set theory ♦ Zermelo set theory

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## ZENO

U Rochester 1978. Euclid with asynchronous message-passing. "Preliminary ZENO Language Description", J.E. Ball et al, SIGPLAN Notices 14(9):17-34 (Sep 1979).

### Nearby terms:

Zen ♦ zen ♦ **ZENO** ♦ zepto ♦ Zermelo Fränkel set theory ♦ Zermelo set theory

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## zepto

### Nearby terms:

zen ♦ ZENO ♦ **zepto** ♦ Zermelo Fränkel set theory ♦ Zermelo set theory

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## Zermelo Fränkel set theory

A set theory with the axioms of Zermelo set theory (Extensionality, Union, Pair-set, Foundation, Restriction, Infinity, Power-set) plus the Replacement axiom schema:

If F(x,y) is a formula such that for any x, there is a unique y making F true, and X is a set, then

{F x : x in X}is a set. In other words, if you do something to each element of a set, the result is a set.

An important but controversial axiom which is NOT part of ZF theory is the Axiom of Choice.

Last updated: 1995-04-10

### Nearby terms:

ZENO ♦ zepto ♦ **Zermelo Fränkel set theory** ♦ Zermelo set theory ♦ ZERO

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## Zermelo set theory

A set theory with the following set of axioms:

Extensionality: two sets are equal if and only if they have the same elements.

Union: If U is a set, so is the union of all its elements.

Pair-set: If a and b are sets, so is

{a, b}.Foundation: Every set contains a set disjoint from itself.

Comprehension (or Restriction): If P is a formula with one free variable and X a set then

{x: x is in X and P(x)}.is a set.

Infinity: There exists an infinite set.

Power-set: If X is a set, so is its power set.

Zermelo set theory avoids Russell's paradox by excluding sets of elements with arbitrary properties - the Comprehension axiom only allows a property to be used to select elements of an existing set.

Zermelo Fränkel set theory adds the Replacement axiom.

[Other axioms?]

Last updated: 1995-03-30

### Nearby terms:

zepto ♦ Zermelo Fränkel set theory ♦ **Zermelo set theory** ♦ ZERO ♦ zero

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## ZERO

<*language*>

An object oriented extension of Z.

["Object Orientation in Z", S. Stepney et al eds, Springer 1992].

Last updated: 1995-03-30

### Nearby terms:

Zermelo Fränkel set theory ♦ Zermelo set theory ♦ **ZERO** ♦ zero ♦ Zero and Add Packed

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## zero

1. 0, ASCI character 48. Numeric zero, as opposed to the letter "O" (the 15th letter of the English alphabet). In their unmodified forms they look a lot alike, and various kluges invented to make them visually distinct have compounded the confusion.

If your zero is centre-dotted and letter-O is not, or if letter-O looks almost rectangular but zero looks more like an American football stood on end (or the reverse), you're probably looking at a modern character display (though the dotted zero seems to have originated as an option on IBM 3270 controllers). If your zero is slashed but letter-O is not, you're probably looking at an old-style ASCII graphic set descended from the default typewheel on the venerable ASR-33 Teletype (Scandinavians, for whom slashed-O is a letter, curse this arrangement).

If letter-O has a slash across it and the zero does not, your display is tuned for a very old convention used at IBM and a few other early mainframe makers (Scandinavians curse *this* arrangement even more, because it means two of their letters collide). Some Burroughs/Unisys equipment displays a zero with a *reversed* slash. And yet another convention common on early line printers left zero unornamented but added a tail or hook to the letter-O so that it resembled an inverted Q or cursive capital letter-O.

Last updated: 1995-01-24

2. To set to zero. Usually said of small pieces of data, such as bits or words (especially in the construction "zero out").

3. To erase; to discard all data from. Said of disks and directories, where "zeroing" need not involve actually writing zeroes throughout the area being zeroed. One may speak of something being "logically zeroed" rather than being "physically zeroed".

See scribble.

Last updated: 1999-02-07

### Nearby terms:

Zermelo set theory ♦ ZERO ♦ **zero** ♦ Zero and Add Packed ♦ zero assignment

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## Zero and Add Packed

<*language*>

(ZAP) An IBM 360/370 assembly language instruction used when performing packed arithmatic to initialise an accumulator.

Last updated: 2001-03-25

### Nearby terms:

ZERO ♦ zero ♦ **Zero and Add Packed** ♦ zero assignment ♦ zero-content ♦ Zero Insertion Force

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## zero assignment

A property of a programming language in which there are no variables but only functions.

See also single assignment.

Last updated: 2003-12-22

### Nearby terms:

Zero and Add Packed ♦ **zero assignment** ♦ zero-content ♦ Zero Insertion Force

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## zero-content

### Nearby terms:

Zero and Add Packed ♦ zero assignment ♦ **zero-content** ♦ Zero Insertion Force ♦ zeroth

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## Zero Insertion Force

<*hardware*>

(ZIF) 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.

Last updated: 1994-12-05

### Nearby terms:

zero assignment ♦ zero-content ♦ **Zero Insertion Force** ♦ zeroth ♦ ZEST

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## zeroth

<*jargon*>

First.

Since zero is the lowest value of an unsigned integer, which is one of the most fundamental types in programming and hardware design, it is often natural to count from zero rather than one, especially when the integer is actually an index or offset, as used when addressing hardware and arrays.

Hackers, computer scientists and pure mathematicians often like to call the first chapter of a publication "Chapter 0", especially if it is of an introductory nature (one of the classic instances was in the First Edition of K&R).

Zero-based numbering tends to reduce fencepost errors, though it cannot eliminate them entirely.

Logically, the next item after the zeroth should be the "oneth" but this is never used.

[Dijkstra, "Why Numbering Should Start at Zero"
*http://www.cs.utexas.edu/users/EWD/transcriptions/EWD08xx/EWD831.html*].

Last updated: 2010-02-28

### Nearby terms:

zero-content ♦ Zero Insertion Force ♦ **zeroth** ♦ ZEST ♦ ZetaLisp ♦ zetta-

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## ZEST

An object-oriented extension of Z.

["Object Orientation in Z", S. Stepney et al eds, Springer 1992].

### Nearby terms:

zero-content ♦ Zero Insertion Force ♦ zeroth ♦ **ZEST** ♦ ZetaLisp ♦ zetta- ♦ zettabyte

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## ZetaLisp

<*language*>

The Maclisp dialect used on the LISP Machine. The many extensions to Maclisp include vectors, closures, flavors, stack groups, locatives, and invisible pointers. Currently supported by Lisp Machines, Inc. and Symbolics.

["LISP Machine Manual", D. Weinreb and D. Moon, MIT AI Lab, 1981].

Last updated: 1997-03-18

### Nearby terms:

Zero Insertion Force ♦ zeroth ♦ ZEST ♦ **ZetaLisp** ♦ zetta- ♦ zettabyte ♦ Zeus

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## zetta-

### Nearby terms:

zeroth ♦ ZEST ♦ ZetaLisp ♦ **zetta-** ♦ zettabyte ♦ Zeus ♦ ZFC ♦ ZF expression

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## zettabyte

(ZB) A unit of data equal to 10^21 bytes but see binary prefix for other definitions. A zetabyte is 1000^7 bytes or 1000 exabytes.

1000 zettabytes are one yottabyte.

See prefix.

Last updated: 2013-11-04

### Nearby terms:

zeroth ♦ ZEST ♦ ZetaLisp ♦ zetta- ♦ **zettabyte** ♦ Zeus ♦ ZFC ♦ ZF expression ♦ ZIF

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## Zeus

### Nearby terms:

ZetaLisp ♦ zetta- ♦ zettabyte ♦ **Zeus** ♦ ZFC ♦ ZF expression ♦ ZIF ♦ zigamorph

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