Semiregular space

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A semiregular space is a topological space whose regular open sets (sets that equal the interiors of their closures) form a base.

Every regular space is semiregular, and every topological space may be embedded into a semiregular space.[1]

Semiregular spaces should not be confused with locally regular spaces, spaces in which there is a base of open sets that induce regular subspaces. For example, the bug-eyed line is locally regular but not semiregular.


  1. ^ Willard, Stephen (2004), "14E. Semiregular spaces", General Topology, Dover, p. 98, ISBN 978-0-486-43479-7 .