Insertion of Continuous Real Functions on Spaces, Bispaces, Ordered Spaces and Pointfree Spaces—A Common Root

摘要

We characterize normal and extremally disconnected biframes in termsof the insertion of a continuous real function in between given lower and upper semicontinuousreal functions and show this to be the common root of several classicaland new insertion results concerning topological spaces, bitopological spaces, orderedtopological spaces and locales.