UGC NET CSE | July 2018 | Part 2 | Question: 34

Question

Pushdown automata can recognize language generated by _______

• A. Only context free grammar
• B. Only regular grammar
• C. Context free grammar or regular grammar
• D. Only context sensitive grammar

Answer 1

Push down automata reconize regular as well as conyext free grammar.

So option c is right

Answer 2

we know that

Regular grammar generates Regular Language ===> Accepted by Finite Automata.

CFG generates CFL ====> Accepted by PDA

 

but PDA = FA + 1 - Auxiliary Memory  = FA+stack

therefore if you are not using the memory of PDA it simply looks as FA.

 

∴ PDA can recognize the language which is generates by either CFG or RG 

Answer 3

Option C

Turing Machine recognises ALL
Linear Bounded Automata  recognises CSL , CFL , RL
Push down automata recognises CFL , RL
Finite Automata recognises only RL