[Solved]: Is DSPACE properly contained in NSPACE?

Problem Detail: It may be a dumb question, but is $mathsf{DSPACE}(f(n)) subset mathsf{NSPACE}(f(n))$ or is $mathsf{DSPACE}(f(n)) subseteq mathsf{NSPACE}(f(n))$? In other words, is the containment relation proper or not? Wikipedia says the first one, while the ComplexityZoo says the other one.

Asked By : NumberFour

Answered By : sdcvvc

It’s open whether $mathsf{DSPACE}(log n) = mathsf{NSPACE}(log n)$, which is the $mathsf{L}=mathsf{NL}$ question. As far as I know, the closest thing we can say are theorems by Savitch $mathsf{NSPACE}(f(n)) subseteq mathsf{DSPACE}(f(n)^2)$ and Immerman–Szelepcsényi’s ($mathsf{NSPACE}$ is closed under complement). Also see AndrewK’s answer regarding the subset symbol, I think this is the issue here.
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