(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

As in title.

2. Relevant equations

Described in my attempt.

3. The attempt at a solution

Where do I go from here? I need to show that those 2 unioned sets are open in A. I'm not seeing it

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# Homework Help: Prove that a retraction is a quotient map

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