Formal language

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 [math]\displaystyle{ \mathcal{L} }[/math] is often used as a variable for formal languages in logic.[1]

Unlike natural languages, the symbols and formulas in formal languages are syntactically and semantically related to one another in a precise way.[2] As a result, formal languages are completely (or almost completely) void of ambiguity.[3]

Examples

Some examples of formal languages include:

  • The set of all words over [math]\displaystyle{ {a, b}\, }[/math]
  • The set [math]\displaystyle{ \left \{ a^{n}\right\} }[/math], where [math]\displaystyle{ n\, }[/math] is a natural number and [math]\displaystyle{ a^n\, }[/math] means [math]\displaystyle{ a\, }[/math] repeated [math]\displaystyle{ n }[/math] times
  • Finite languages, such as [math]\displaystyle{ \{\{a,b\},\{a, aa, bba\}\}\, }[/math]
  • 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:

Formal Language Media

Related pages

References

  1. "Comprehensive List of Logic Symbols". Math Vault. 2020-04-06. Retrieved 2020-10-09.
  2. "Definition of formal language | Dictionary.com". www.dictionary.com. Retrieved 2020-10-09.
  3. "1.11. Formal and Natural Languages — How to Think like a Computer Scientist: Interactive Edition". runestone.academy. Retrieved 2020-10-09.

Further reading

  • Hopcroft, J.; Ullman, J. (1979). Introduction to Automata Theory, Languages, and Computation. Addison-Wesley. ISBN 0-201-02988-X.
  • Rasiowa, Helena; Sikorski, Roman (1970). "Chapter 6. Algebra of formalized languages". The Mathematics of Metamathematics (3rd ed.). PWN.
  • Rozemberg, G.; Salomaa, A., eds. (1979). Introduction to Automata Theory, Languages, and Computation. Addison-Wesley. ISBN 978-3-540-61486-9.

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