Formal language facts for kids
In mathematics, computer science and linguistics, a formal language is one that has a particular set of symbols, and whose expressions are made according to a particular set of rules. The symbol 
is often used as a variable for formal languages in logic.
Unlike natural languages, the symbols and formulas in formal languages are syntactically and semantically related to one another in a precise way. As a result, formal languages are completely (or almost completely) void of ambiguity.
Contents
Examples
Some examples of formal languages include:
- The set of all words over
- The set
, where 
is a natural number and 
means 
repeated 
times - Finite languages, such as
- The set of syntactically correct programs in a given programming language
- The set of inputs upon which a certain Turing machine halts
Specification
A formal language can be specified in a great variety of ways, such as:
- Strings produced by some formal grammar (see Chomsky hierarchy)
- Strings described or matched by a regular expression
- Strings accepted by some automaton, such as a Turing machine or finite state automaton
- Strings indicated by a decision procedure (a set of related yes/no questions) where the answer is 'yes'
Related pages
- Language for languages in general
- Syntax for the form of a language in general
- Semantics for the meanings in a language
- Natural language for languages that are not formal
- Computer language for application of formal languages in computing
- Programming language for the application of formal languages to program computers
, chapter 6 Algebra of formalized languages.
See also
In Spanish: Lenguaje formal para niños
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Formal language Facts for Kids. Kiddle Encyclopedia.