Which one of the following problems is undecidable?
(A) is the answer. Proving (A) is undecidable is not so easy. But we can easily prove the other three options given here are decidable.
Context free grammar is not closed under ambiguity.A set is closed under an operation means when we operate an element of that set with that operator we get an element from that set. Here, context free grammar generates a context free language and set of all context free languages is also a set. But, ambiguity is not an operation and hence we can never say that CFG is closed under ambiguity. Thus, problem mentioned in option (A) is undecidable.
Sir what's the difference between option c) of this question and "G is a CFG. Is L(G)=ϕ?"(which is undecidable as per Rice's Theorem https://gateoverflow.in/1553/gate2013_41).
#Pcs See it ... Its a trivial property i think ... We jst need to care abt the terminals to get the result ...
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