Where: A, B are nonterminals; a is terminal; α, β, γ are strings of terminals/nonterminals.
An abstract self-operating machine (mathematical model) that processes strings and decides whether to accept or reject them. formal languages and automata theory notes pdf
| 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 | Where: A, B are nonterminals; a is terminal;
Prove aⁿbⁿcⁿ is not context-free using pumping lemma. B are nonterminals