Ranks for baire multifunctions
Tom 95 / 2003
Colloquium Mathematicum 95 (2003), 63-77 MSC: 03E15, 26A21, 54C60. DOI: 10.4064/cm95-1-6
Various ordinal ranks for Baire-1 real-valued functions, which have been used in the literature, are adapted to provide ranks for Baire-1 multifunctions. A new rank is also introduced which, roughly speaking, gives an estimate of how far a Baire-1 multifunction is from being upper semicontinuous.