Paper 3, Section I,
Part II, 2019
(a) Define what it means for a context-free grammar (CFG) to be in Chomsky normal form (CNF). Can a CFG in CNF ever define a language containing ? If denotes the result of converting an arbitrary CFG into one in CNF, state the relationship between and .
(b) Let be a CFG in CNF. Give an algorithm that, on input of any word on the terminals of , decides if or not. Explain why your algorithm works.
(c) Convert the following CFG into a grammar in CNF:
Does in this case? Justify your answer.