CSE104, Lec 9: Savitch's theorem, PSPACE = NPSPACE

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A discussion of the basic bounds on relating time and space complexity classes. Savitch's theorem and why PSPACE = NPSPACE
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15:15 This is interesting. My book says O(2^f(n)) but it could be wrong. Anyway, you say that a configuration is a string of length s(n) over alphabet Σ ∪ Q, but that's not entirely true. Yes, Σ could be binary and Q a set with a larger amount of symbols, but in any configuration string only one symbol of the string is a Q-symbol. So there are a large amount of combinations over the alphabet that are unacceptable strings: all those with more than one Q-symbol. Actually, for s(n) large enough, I think we can assume the alphabet simply binary because only one Q-symbol is negligible. What you think?

willayou