Definition

Chomsky Hierarchy: A Comprehensive Guide

Definition

The Chomsky hierarchy, also known as the Chomsky-Schützenberger hierarchy, is a classification system developed by Noam Chomsky to categorize formal grammars and the languages they generate.

Types of Grammars

According to Chomsky, there are four main types of grammars:

1. Type 0: Unrestricted Grammars

These grammars have no restrictions on the form of their production rules. They can generate any language, including natural languages.

2. Type 1: Context-Sensitive Grammars

These grammars have production rules that can only be applied when the surrounding context meets certain conditions.

3. Type 2: Context-Free Grammars

These grammars have production rules that can only be applied to a single non-terminal symbol, regardless of the surrounding context.

4. Type 3: Regular Grammars

These grammars have production rules that only allow for the addition, deletion, or replacement of a single symbol.