Used for, with some effort

[posic]

Написал два коммента к http://mathoverflow.net/questions/48191/how-mathematicians-knowledge-is-organized

Comments

[(Anonymous)]

What the tip-of-the-tongue knowledge of what the notion of compactness is used for is supposed to be used for? – Leonid Positselski yesterday

For example:

Compactness is a generalisation/replacement of finiteness for infinite objects, e.g. you can take averages and maximums of functions. Arbitrary functions, that is, but you need to assume continuity of course.

[posic.livejournal.com]

This is an answer to a different question.