TOC Introduction Of Grammer

TOC Introduction Of Grammer

 Introduction to Grammar in Theory of Computation (TOC)

In Theory of Computation (TOC), Grammar is a set of rules that defines how strings in a language are formed. It is mainly used to generate and analyze formal languages.

 What is Grammar in TOC?

A Grammar (G) in TOC is formally defined as:
G = (V, T, P, S)

Where:

• V (Variables/Non-terminals): Set of symbols that can be replaced.

• T (Terminals): Set of symbols that appear in the final string.

• P (Production Rules): Rules that define how variables can be replaced by terminals or other variables.

• S (Start Symbol): The initial variable from which derivations begin.

 Example of a Grammar

Consider a simple grammar:
G = ({S}, {a, b}, {S → aSb | ab}, S)

Production Rules:
S → aSb
S → ab

Generated Strings:

• ab (using rule 2)

• aabb (using rule 1 followed by rule 2)

• aaabbb (using rule 1 twice and then rule 2)

This grammar generates a language of balanced a and b pairs (like ab, aabb, aaabbb, etc.).

 Types of Grammar (Chomsky Hierarchy)

Noam Chomsky classified grammars into four types:

 Importance of Grammar in TOC

 Used in Compilers for parsing programming languages.
 Helps in designing automata (Finite Automata, Pushdown Automata, Turing Machines).
 Forms the basis of syntax analysis in Natural Language Processing (NLP).

 Summary

• Grammar defines the structure of languages in TOC.

• It consists of V (Variables), T (Terminals), P (Productions), and S (Start Symbol).

• Chomsky Hierarchy classifies grammars into four types.

• It is widely used in Compilers, NLP, and Automata Theory.

 Do you need more examples or explanations on any type of grammar?

TOC Introduction Of Grammer

Introduction to Grammar in Theory of Computation (TOC)

In Theory of Computation (TOC), Grammar is a formal way to describe the syntax of a language. It specifies how strings in a language can be formed using a set of production rules.

What is Grammar?

A grammar is a 4-tuple:

$$G=(V,\Sigma ,R,S)$$

Where:

• V = Set of variables (non-terminals)

• Σ = Set of terminals (input symbols or alphabet)

• R = Set of production rules (how symbols can be replaced)

• S = Start symbol (a variable from where derivation begins)

Example

Let’s define a simple grammar for language L = { aⁿbⁿ | n ≥ 1 }

$$G=(\{S\},\{a,b\},\{S\to aSb,S\to ab\},S)$$

Here:

• Start with S

• Use rules to derive strings like:

  • $S\Rightarrow aSb\Rightarrow aaSbb\Rightarrow aaabbb$

This grammar generates strings with equal numbers of a’s and b’s in correct order.

Types of Grammars (Chomsky Hierarchy)

Key Points to Remember

• Production Rule Format:

  • Regular Grammar: A → aB or A → a

  • CFG: A → α (α can be any combination of terminals and non-terminals)

• Derivation: The process of applying rules to generate strings.

• Parse Tree: A tree representation showing how the grammar generates a string.

Want a Quick Video?

Would you like a video recommendation that explains grammar concepts with animations and GATE questions? I can find one for you!

Let me know if you also want:

• Practice problems

• A grammar quiz

• Derivation examples with parse trees

I’m happy to provide!

TOC Introduction Of Grammer

Introduction to Languages and Grammars