When are Borel functions Baire functions?
Tom 143 / 1993
Fundamenta Mathematicae 143 (1993), 137-152
DOI: 10.4064/fm-143-2-137-152
Streszczenie
The following two theorems give the flavour of what will be proved. Theorem. Let Y be a complete metric space. Then the families of first Baire class functions and of first Borel class functions from [0,1] to Y coincide if and only if Y is connected and locally connected.} Theorem. Let Y be a separable metric space. Then the families of second Baire class functions and of second Borel class functions from [0,1] to Y coincide if and only if for all finite sequences $U_1,...,U_q$ of nonempty open subsets of Y there exists a continuous function ϕ:[0,1] → Y such that $ ϕ^{-1}(U_i) ≠Ø$ for all i ≤ q.
