Q. 50 Let L(R) be the language represented by regular expression R. Let L(G) be the language generated by a context free grammar G. Let L(M) be the language accepted by a Turing machine M. Which of the following decision problems are undecidable?
I. Given a regular expression R and a string w, is w∈L(R)?
II. Given a context-free grammar G, is L(G)=∅
III. Given a context-free grammar G, is L(G)=Σ∗ for some alphabet Σ?
IV. Given a Turing machine M and a string w, is w ∈ L(M)?
(A) I and IV only
(B) II and III only
(C) II, III and IV only
(D) III and IV only
Answer: (D)
Explanation:
