Question

the complement of a regularly open set is regularly. a. open
b.closed c.bounded d.finite​

Answer 1

Answer:

Regular b-open sets (rb-open sets)

In this section we introduce a new class of open sets called rb-open sets. Definition 4.1: A set A ⊂ X is said to be regular b-open (briefly rb-open) if its complement is a regular b-closed set.