It is proved that -mappings preserve absolute Borel classes, which improves results of R. W. Hansell, J. E. Jayne and C. A. Rogers. The proof is based on the fact that any -mapping f: X → Y of an absolute Suslin metric space X onto an absolute Suslin metric space Y becomes a piecewise perfect mapping when restricted to a suitable -set satisfying .
@article{bwmeta1.element.bwnjournal-article-doi-10_4064-fm182-3-1, author = {Petr Holick\'y and Ji\v r\'\i\ Spurn\'y}, title = {$F\_{$\sigma$}$-mappings and the invariance of absolute Borel classes}, journal = {Fundamenta Mathematicae}, volume = {184}, year = {2004}, pages = {193-204}, zbl = {1059.54025}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-fm182-3-1} }
Petr Holický; Jiří Spurný. $F_{σ}$-mappings and the invariance of absolute Borel classes. Fundamenta Mathematicae, Tome 184 (2004) pp. 193-204. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-fm182-3-1/