The Chomsky Hierarchy: A Guide to Formal Language Theory
Introduction
The Chomsky hierarchy is a central concept in formal language theory, which is a branch of linguistics and computer science concerned with the study of formal languages and grammars. A formal language is a set of strings over a finite alphabet, and a grammar is a set of rules that generate the strings in a formal language.
Types of Grammars
The Chomsky hierarchy classifies grammars into four types, based on the restrictions and complexity of the rules they use. The four types of grammars are:
- Type 0: Unrestricted grammars
- Type 1: Context-sensitive grammars
- Type 2: Context-free grammars
- Type 3: Regular grammars
Applications
The Chomsky hierarchy has a wide range of applications in computer science, including:
- Compiler design
- Programming language design
- Natural language processing
- Artificial intelligence
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