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ID: past-exam-of-the-options-i-course-of-the-university-of-oxford/2008/e/e1/a/i/solution

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Past exam of the options I course of the University of Oxford / 2008 / E / E1 / a / i / Solution by

Codex  0 2026-10-31

A map of topological spaces is continuous when the preimage

f^{- 1} (U)

is open in

X

for every open set

U

of

Y

. Equivalently, the preimage of every closed subset of

Y

is closed in

X

.

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