Formal Languages And Automata Theory Notes Pdf Official

1. Introduction Formal Language: A set of strings (sequences of symbols) constrained by specific rules, formed over an alphabet (a finite set of symbols, denoted Σ).

Prove n≥0 is not context-free using pumping lemma.

Design CFG for balanced parentheses.

What are the capabilities and limitations of computing devices? 2. Basic Terminology | Term | Definition | Example | |------|------------|---------| | Alphabet (Σ) | Finite, non-empty set of symbols | Σ = a, b | | String (Word) | Finite sequence of symbols over Σ | aabb | | Empty String (ε) | String with zero symbols | ε | | Length | Number of symbols in a string | | aab | = 3 | | Kleene Star (Σ*) | Set of all possible strings over Σ (incl. ε) | ε, a, b, aa, ab, ... | | Kleene Plus (Σ⁺) | Σ* without ε | a, b, aa, ab, ... | | Language (L) | Any subset of Σ* | L = strings starting with 'a' | 3. Classification of Grammars (Chomsky Hierarchy) Noam Chomsky classified formal grammars into four types, each generating a specific class of languages.

Where: A, B are nonterminals; a is terminal; α, β, γ are strings of terminals/nonterminals. formal languages and automata theory notes pdf

Convert NFA to DFA.

| Type | Grammar Name | Language Class | Automaton | Production Rule Form | |------|--------------|----------------|------------|----------------------| | Type 0 | Unrestricted | Recursively Enumerable | Turing Machine | α → β (any) | | Type 1 | Context-Sensitive | Context-Sensitive | Linear Bounded Automaton (LBA) | αAβ → αγβ (γ ≠ ε) | | Type 2 | Context-Free | Context-Free | Pushdown Automaton (PDA) | A → γ | | Type 3 | Regular | Regular | Finite Automaton (FA) | A → aB or A → a | Design CFG for balanced parentheses

An abstract self-operating machine (mathematical model) that processes strings and decides whether to accept or reject them.