Which type of automata is used to recognize context-free languages?

Push-down automata

Fill in the blank: A grammar G = (V, ∑, P, S) is context-free if productions are of the form ______.

Α → β where α is a single non-terminal

True or False: Every regular grammar is context-free.

True

Riddle: I can generate strings like ab and aab, but I can also produce ε. What am I?

A context-free grammar with productions for a's and b's

What are the two methods to check if a string belongs to a context-free language?

Derivations and reductions

Which normal form requires productions to be of the form A → a or A → BC?

Chomsky normal form (CNF)

Fill in the blank: Context-sensitive grammars are more powerful than ______.

Context-free grammars

True or False: The pumping lemma can definitively prove that a language is context-free.

False. It can only be used to show that a language is not context-free.

Which context-free language cannot be recognized by a deterministic pushdown automaton?

L = { a^n b^n c^n | n ≥ 0 }

Riddle: I am a language defined by rules, where the number of a's, b's, and c's must match, but I cannot be context-free. What am I?

The language L = { a^n b^n c^n | n ≥ 0 }