Tuesday, 17 March 2015

gn.general topology - Topologies making a class of functions continuous

Let $X:={f: mathbb{C}to mathbb{C}}$ be a class of total functions on $mathbb{C}$ closed under composition, addition, multiplication, and scalar multiplication. Does there exist a topology on $mathbb{C}$ making these functions and only these functions continuous?



If it's not true in general (it probably isn't), are there any interesting known cases where it is true?



Note: I emphasize total functions because we want them to be everywhere defined. This avoids functions with bad singularities.



Edit: Obviously, continuous functions in the standard topology fit this bill, but this is tautological and not in the spirit of the problem.



Edit 2: Apparently the way I asked this question made it seem like I was looking for an answer to the "general case" which seems pretty untrue although I haven't actually worked it out. Rather, the real question was interesting cases where it is true.

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