Consider this sentence:
We demand that the university close all bookstores on Sunday.
The hypothetical "close" is not in the normal present tense "closes" that I would use if I were to describe the university's response:
The university now closes its bookstores on Sunday.
I believe both sentences are grammatically correct (being a native speaker), but I do not know, formally, why the first is correct. What is the tense used in the hypothetical clause, and what are the rules for when to apply it?