17 WS Aufgabe 4 e

Question

In task 4 e, you have to show that a word is not in the given grammar. Is it sufficient to give a non-terminable derivation tree? If not, how do you solve this task formally correctly?

Answer 1

This is one of the strengths of deterministic parsing. There is unique parse tree that is generated by the parse table for a LL or LR grammar regardless whether that word is accepted or not. The exam problem you are considering is asking for that derivation/parse tree, and the final result whether it was accepting or not.