symbolic from FOLDOC

Symbolic Assembler Program

<language>

(SAP) The assembly language for the IBM 704, defined in the late 1950s.

Last updated: 1994-12-12

SYMBOLIC ASSEMBLY

<language>

An early system on the IBM 705.

[Listed in CACM 2(5):16, May 1959].

Last updated: 1996-01-15

Symbolic Automatic INTegrator

<mathematics, tool>

(SAINT) A symbolic mathematics program written in Lisp by J. Slagle at MIT in 1961.

[Sammet 1969, p. 410].

Last updated: 1994-12-08

symbolic inference

The derivation of new facts from known facts and inference rules. This is one of the fundamental operations of artificial intelligence and logic programming languages like Prolog.

Inference is a basic part of human reasoning. For example given that all men are mortal and that Socrates is a man, it is a trivial step to infer that Socrates is mortal. We might express these symbolically:

 man(X) => mortal(X).
 man(socrates).

("if X is a man then X is mortal" and "Socrates is a man"). Here, "man", "mortal" and "socrates" are just arbitrary symbols which the computer manipulates without reference to or knowledge of their external meaning. A forward chaining system (a production system) could use these to infer the new fact

 mortal(socrates).

simply by matching the left-hand-side of the implication against the fact and substituting socrates for the variable X.

Last updated: 1994-10-28

Symbolic Link

<file format>

(SYLK) A Microsoft file format for spreadsheets, (not to be confused with symbolic link).

SYLK format existed in one form or another in as early as 1987, and was part of Excel v1.0. It is is an outgrowth of VisiCalc DIF file format.

SYLK format is ascii text and represents information about both formula, value, and some formatting information, which makes it something like an RTF for spreadsheets. It is used as a general tabular data exchange format.

http://netghost.narod.ru/gff/graphics/summary/micsylk.htm.

[Reference?]

Last updated: 2004-04-08

symbolic link

<file system>

(Or "symlink", "soft link" (by contrast with "hard link"), "shortcut", "alias") A special type of Unix file which refers to another file by its pathname. A symbolic link is created with the "ln" (link) command:

 ln -s OLDNAME NEWNAME

Where OLDNAME is the target of the link (usually a pathname) and NEWNAME is the pathname of the link itself.

Most operations (open, read, write) on the symbolic link automatically dereference it and operate on its target (OLDNAME). Some operations (e.g. removing) work on the link itself (NEWNAME).

In contrast with hard links, there are no restrictions on where a symbolic link can point, it can refer to a file on another file system, to itself or to a file which does not even exist (e.g. when the target of the symlink is removed). Such problems will only be detected when the link is accessed.

Last updated: 1997-10-22

symbolic logic

<logic>

The discipline that treats formal logic by means of a formalised artificial language or symbolic calculus, whose purpose is to avoid the ambiguities and logical inadequacies of natural language.

Last updated: 1995-12-24

Symbolic Mathematical Laboratory

<tool, mathematics>

An on-line system under CTSS for symbolic mathematics. It used a display screen and a light pen.

[Sammet 1969, p.514].

Last updated: 1995-04-16

symbolic mathematics

<mathematics, application>

(Or "symbolic math") The use of computers to manipulate mathematical equations and expressions in symbolic form, as opposed to manipulating the numerical quantities represented by those symbols. Such a system might be used for symbolic integration or differentiation, substitution of one expression into another, simplification of an expression, change of subject etc.