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Tagged with decidability pushdown-automata
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Useless states in a PDA
I am trying to solve a problem in Sipser's Introduction to the Theory of Computation book, which reads:
4.22 A useless state in a pushdown automaton is never entered on any input string. Consider the ...
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Why finiteness problem of CFL is decidable?
We know that every $CFL$ has infinite configuration space. Due to this equality problem is undecidable. But why finiteness property is decidable inspite having infinite configuration space?
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