GATE CSE 2008
Q61.
Which of the following are decidable? I. Whether the intersection of two regular languages is infinite II. Whether a given context-free language is regular III. Whether two push-down automata accept the same language IV. Whether a given grammar is context-freeQ62.
Which of the following tuple relational calculus expression(s) is/are equivalent to \forall t \in r(P(t))? I. \neg \exists t \in r(P(t)) II. \neg t \notin r(P(t)) III. \neg \exists t \in r(\neg P(t)) IV. \exists t \in r(\neg P(t))