Language

Language ($L$) a (possibly infinite) set of strings. One can say this is a set of all sentence can be said in this language.

There are different ways to specify language, for example:

• Automata - if automata accpets string than it’s part of the language
• Grammar (generative or recognition-based)
  • Regular expressions
  • Chomsky grammar
  • Indexed grammar
  • Tree adjoining grammar
  • Multiple context-free grammar
  • PEG
  • etc.
• system of languge equations