Relationship between PDA and context-free languages MCQs

By: Prof. Dr. Fazal Rehman Shamil | Last updated: September 23, 2024

MCQs on Relationship between PDA and Context-Free Languages
Which of the following statements best describes the relationship between Pushdown Automata (PDA) and context-free languages (CFL)?

A) PDAs recognize exactly the context-free languages.
B) PDAs recognize a proper subset of the context-free languages.
C) PDAs recognize a superset of the context-free languages.
D) PDAs recognize all regular languages but none of the context-free languages.
Answer: A) PDAs recognize exactly the context-free languages.

What is a key characteristic of a Pushdown Automaton (PDA) that allows it to recognize context-free languages?

A) It has a finite amount of memory.
B) It has an unbounded tape for input.
C) It has a stack for storing symbols.
D) It can perform non-deterministic transitions.
Answer: C) It has a stack for storing symbols.

Which of the following is true regarding the operation of a Pushdown Automaton (PDA)?

A) It reads input symbols from left to right and accepts if the stack is empty.
B) It reads input symbols from right to left and accepts if the input tape is empty.
C) It reads input symbols from left to right and accepts if the input tape is empty.
D) It reads input symbols from right to left and accepts if the stack is empty.
Answer: C) It reads input symbols from left to right and accepts if the input tape is empty.

True or False: Every context-free language can be recognized by some Pushdown Automaton (PDA).

A) True
B) False
Answer: A) True

Which of the following is a correct statement about the computational power of a Pushdown Automaton (PDA)?

A) PDAs are more powerful than Turing Machines.
B) PDAs are less powerful than Turing Machines.
C) PDAs are equivalent in power to Turing Machines.
D) PDAs are equivalent in power to Finite Automata.
Answer: B) PDAs are less powerful than Turing Machines.

In the context of Pushdown Automata, what role does the stack play in recognizing context-free languages?

A) It allows the PDA to recognize non-context-free languages.
B) It provides additional memory to store symbols temporarily.
C) It stores the input symbols permanently.
D) It determines the alphabet used by the PDA.
Answer: B) It provides additional memory to store symbols temporarily.

Which of the following statements is true regarding closure properties of context-free languages?

A) Context-free languages are closed under complementation.
B) Context-free languages are closed under intersection.
C) Context-free languages are closed under Kleene star.
D) Context-free languages are closed under subtraction.
Answer: C) Context-free languages are closed under Kleene star.

Which construction method is typically used to convert a context-free grammar into an equivalent Pushdown Automaton (PDA)?

A) Subset Construction
B) Union Construction
C) Grammar Conversion
D) Conversion to Regular Expression
Answer: A) Subset Construction

Which aspect of Pushdown Automata distinguishes them from Finite Automata when recognizing languages?

A) The ability to recognize non-context-free languages.
B) The use of an unbounded tape for input.
C) The presence of a stack for storing symbols.
D) The ability to perform parallel computations.
Answer: C) The presence of a stack for storing symbols.

 

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