## How to convert NPDA to PDA?

I have been given this Nondeterministic pushdown automata and I need to convert it to deterministic pushdown automata, I have been stuck with this for a while now, I know that there cant be transitions where the pda doesnt read anything from the stack but i dont know how to solve this.

## Is it decidable for a NPDA to halt?

I know that it is decidable for an NPDA to accept a string $$w$$, i.e. a TM can receive as input the description of an NPDA along with a string and test if the NPDA accepts the string.

But are there languages where given an NPDA description as input, the TM may not halt, i.e. since the simulated NPDA also does not halt…

## Difference between the npda languages

I have to got two questions related to npda:

Q1. Construct an npda for L = {a_concatenation_n b_concatenation_2n | n ≥ 0} on Σ= {a, b, c}. & the language in the following question:

Q2. Construct an npda for L = {w ∈ {a, b, c}* | na(w) = 2nb(w)}

What is the difference in the above two languages?

Zulfi.

## Converting an NPDA to a CFG

I have a question regarding conversion of NPDA to CFG. The above picture is from my lecture slides. I dont understand why they are saying 1 can be popped while transitioning from q0 to q1. It is in the first grammar production after the “or” symbol. Also, it would be great if someone explained how the conversion is working for this example in specific. Thanks!

## NPDA question about accepting condition

Will an NPDA accept a string that reaches a final state but does not have all its input consumed yet?

## Difference between DPDA and NPDA?

What are the major differences between Deterministic Push Down Automata and Non-deterministic Push Down Automata? Which one is faster and how? Also what are the drawbacks of DPDA with respect to NPDA. Can anyone quote an example and explain these concepts.

## How to draw NPDA for ** \[a^{m}b^{n}\mid m

I know that CFG for $$a^{m}b^{n}\mid m\leq n\leq 2m$$ is $$S\rightarrow ab/abb/aSb/aSbb$$ but I am not able to tweak it in such a way that it is strictly in between m and 2m and not equal to any of m or 2m. I want to draw PDA for the same.