Karl Jones: Created page with "In logic, a '''metavariable''' (also '''metalinguistic variable''' or '''syntactical variable''') is a symbol or symbol string which belongs to a metalanguage and..."

2016-09-13T16:53:11Z

Created page with "In logic, a '''metavariable''' (also '''metalinguistic variable''' or '''syntactical variable''') is a symbol or symbol string which belongs to a metalanguage and..."

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In [[logic]], a '''metavariable''' (also '''metalinguistic variable''' or '''syntactical variable''') is a [[symbol]] or symbol string which belongs to a [[metalanguage]] and stands for elements of some object language.

For instance, in the sentence

Let A and B be two sentences of a language ℒ

the symbols A and B are part of the metalanguage in which the statement about the object language ℒ is formulated.

[[John Corcoran]] considers this terminology unfortunate because it obscures the use of schemata and because such "variables" do not actually range over a domain.

The convention is that a metavariable is to be uniformly substituted with the same instance in all its appearances in a given schema. This is in contrast with nonterminal symbols in formal grammars where the nonterminals on the right of a production can be substituted by different instances.

Attempts to formalize the notion of metavariable result in some kind of [[type theory]].

In [[computing]] one often needs to specify and document the syntax and semantics of a computer language, more or less formally. A term often used for metavariable in that area is [[metasyntactic variable]].

Furthermore, because of the common practice in hacker culture to use nonsense words like "foo" as metavariables, the term "metasyntactic variable" has come to denote such words by themselves; for instance, "foo" is referred to as "the first metasyntactic variable" in the first edition of The Hacker's Dictionary.

== See also ==

* [[Explicit substitution]]

== External links ==

* [https://en.wikipedia.org/wiki/Metavariable Metavariable] @ Wikipedia.org

[[Category:Computing]]
[[Category:Games]]
[[Category:Logic]]
[[Category:Mathematics]]

Metavariable - Revision history

Karl Jones: Created page with "In logic, a '''metavariable''' (also '''metalinguistic variable''' or '''syntactical variable''') is a symbol or symbol string which belongs to a metalanguage and..."