Which of the following are decidable?
1) Whether the intersection of two regular language is infinite.
2) Whether a given context free language is regular.
3) Whether two push down automata accept the same language.
4) Whether a given grammar is context free.

Related MCQs

• Match all items in Group 1 with correct options from those given in Group 2. List I List II**spaceP. Regular Expression 1. Syntax analysis**spaceQ. Push down automata 2. Code Generation**spaceR. Dataflow analysis 3. Lexical analysis**spaceS. Register allocation 4. Code optimization
• Let P be a regular language and Q be context-free language such that Q ∈ P. (For example, let P be the language represented by the regular expression p*q* and Q be {pnqn n∈ N}). Then which of the following is ALWAYS regular?
• Which of the following statements is/are FALSE? (1) For every non-deterministic Turing machine, there exists an equivalent deterministic Turing machine. (2) Turing recognizable languages are closed under union and complementation. (3) Turing decidable languages are closed under intersection and complementation (4) Turing recognizable languages are closed under union and intersection.
• The language accepted by a Push down Automata:
• The language accepted by a Push down Automata:
• If L1 and L2 are context free language and R a regular set, then which one of the languages below is not necessarily a context free language?
• Fred created a new automaton model which is a push down automaton but with two stacks and the added ability of having commands which do not read input tape but which can pop from one stack and push into the other.This new automaton can recognize (choose strongest result)
• For two regular languages L1 = (a + b)* a and L2 = b (a + b ) *, the intersection of L1 and L2 is given by
• Consider the following statements about the context free grammar G = {S - >SS,S - >ab,S ->ba, S - ε} I. G is ambiguous II. G produces all strings with equal number of a’s and b’s III. G can be accepted by a deterministic PDA. Which combination below expresses all the true statements about G?
• Let L be any infinite regular language, defined over an alphabet Σ then there exist three strings x, y and z belonging to Σ such that all the strings of the form XY^ n Z for n=1,2,3, … are the words in L called