Abstract:
We present an regular space that is not completely regular but only barely so: not only is it first-countable, but in addition all closed sets are $G_\delta$-sets and all points are zero-sets. This answers a question about how the lattice of zero-sets is situated in the lattice of all open sets.
Some intermediate results on the Niemytzki plane make excellent homework exercises for a topology course.
Notes:
The paper is, and the slides will be, available via my website
Scheduled for: 2026-03-11 10:20 AM: General & ST Session #1.1 in Heritage Hall Building 124
Status: Accepted
Collection: General and Set-Theoretic Topology
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