# Michael Sipser Edition 3 Exercise 5 Question 33 (Page No. 241)

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Consider the problem of determining whether a $PDA$ accepts some string of the form $\{ww \mid w \in \{0,1\}^{\ast} \}$ . Use the computation history method to show that this problem is undecidable.

Language acceptance by CFL is undecidable.

As easy as that.

Only membership, emptiness and finiteness only decidable.
let’s assume w= 01

for ww, it will be 0101

Since the first and the last symbol is different.Hence, the problem is undecidable
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