Seminario: “Some computable functions without Brouwer fixed-points”

Martedì 24 Ottobre 2017, ore 16:30 - Sala Riunioni VII Piano - Petrus Potgieter


Martedì 24 Ottobre 2017 alle ore 16:30 in Sala Riunioni VII Piano, Petrus Potgieter (University of South Africa) terrà un seminario dal titolo “Some computable functions without Brouwer fixed-points”.

The Brouwer fixed-point theorem is essentially non-constructive and non-computable since there exist computable functions without computable fixed points. Examples of Orevkov and Baigger imply that there is no procedure for finding the fixed point in general by giving an example of a computable function which does not fix any computable point. We discuss this and some illustrative examples as well as the perception that the Sperner lemma provides a constructive proof of the theorem.