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• CommentRowNumber1.
• CommentAuthorTodd_Trimble
• CommentTimeAug 17th 2015

At closed subspace, I added some material on the 14 operations derivable from closures and complements. For no particularly great reason except that it’s a curiosity I’d never bothered to work through until now.

• CommentRowNumber2.
• CommentAuthorTodd_Trimble
• CommentTimeAug 18th 2015

I’ve been adding more assorted observations to closed subspace, interior, and boundary.

• CommentRowNumber3.
• CommentAuthorTodd_Trimble
• CommentTimeAug 18th 2015

Also Thomas Holder added some nice material at boundary in a section “Some ramifications”.

• CommentRowNumber4.
• CommentAuthorUrs
• CommentTimeMar 17th 2017

the entry closed subspace used to request a link to law of double negation. To un-gray the link, I have created such an entry.

• CommentRowNumber5.
• CommentAuthorUrs
• CommentTimeApr 10th 2017
• (edited Apr 10th 2017)

in the vein of adding elementary proofs of basic facts in topology, I added statement and proof for metric spaces of the characterization of closed subspaces via converging sequences, here

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