I can't understand what my professor wrote about these inclusions concerning deterministic classes:
$$ DTIME(f) \subseteq DSPACE(f) \subseteq \sum_{c\in\Bbb N}DTIME(2^{c(log+f)}) $$
I understood the first inclusion:
The Turing Machine needs to do at least one step in order to check the next cell on tape
I didn't get the second one:
The number of configurations of the Turing Machine with fixed space is finite, and the computation must stop within a maximum number of steps equal to these settings, otherwise wewould have a cycle.
I don't understand the argument of the summation: why that $2$ and that $c(log+f)$? Why is it written like that?