- #1

ehrenfest

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## Homework Statement

If you have a collection of disjoint open sets in a general topological space whose union is open, is it true that each of them individually must be open? Why?

EDIT: this makes absolutely no sense. here is what I meant to ask:

EDIT:If you have a collection of disjoint sets in a general topological space whose union is open, is it true that

EDIT:each of them individually must be open? Why?

## Homework Equations

## The Attempt at a Solution

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