Absolute $\mathcal F$-Borel classes
Absolute $\mathcal F$-Borel classes
We investigate and compare $\mathcal F$-Borel classes and absolute $\mathcal F$-Borel classes. We provide precise examples distinguishing these two hierarchies. We also show that for separable metrizable spaces, $\mathcal F$-Borel classes are automatically absolute.