Understanding Regular Grammar
Regular grammar is a formal grammar that is used to define regular languages, which can be recognized by finite automata. The key characteristics of regular grammar are essential for distinguishing it from other types of grammars.
Key Characteristics of Regular Grammar:
- Definition: Regular grammar comprises productions where the left-hand side consists of a single non-terminal symbol, and the right-hand side can be either a terminal symbol or a terminal symbol followed by a non-terminal symbol.
- Types: There are two types of regular grammars: right-linear and left-linear. In right-linear grammars, the non-terminal appears at the right end of the production, while in left-linear grammars, it appears at the left end.
- Language Recognition: Regular grammars generate languages that can be recognized by finite state machines. This means that the languages they produce have a limited structural complexity.
Comparison with Context-Free Grammar:
- Context-Free Grammar (CFG): This is a more powerful type of grammar that allows for productions where the left-hand side can be a single non-terminal and the right-hand side can be a string of terminals and non-terminals. CFGs can describe languages that require a stack for recognition, such as balanced parentheses.
- Inclusion: All regular languages are also context-free, meaning that regular grammars are a subset of context-free grammars. However, not all context-free grammars are regular.
Conclusion:
Given these characteristics and relationships, the correct answer to the question is option 'D' - "context-free grammar." Regular grammar is indeed a specific form of context-free grammar that captures simpler structures within formal language theory.