List of top Data Science A.I Cyber Security and Computer Sci. Questions on Theory of Computations

If L and L are recursively enumerable, then L is:

Let P be a regular language and Q be a context-free language such that Q ⊆ P. Then which of the following is always regular?

Which of the following languages are context-free?

Finite Languages satisfy the pumping lemma by having n = .

Match List I with List II.

LIST I	LIST II
(A) Unification	(I) Variable can be done with a constant, another variable, or a function.
(B) Deep backtracking	(II) The entire conjunctive goal is executed.
(C) Forward movement	(III) Choose subgoal with possible unifier.
(D) Shallow backtracking	(IV) Previous subgoal to find alternative solutions.

Consider the FOL sentence F: ∀x(∃y R(x, y)). Assuming non-empty logical domains, which of the sentences below are implied by F?
(A) ∃y(∃x R(x, y))
(B) ∃y(∀x R(x, y))
(C) ∀y(∃x R(x, y))
(D) ¬∃x(∀y ¬R(x, y))
Choose the correct answer from the options given below: