David Belanger: An effective perfect-set theorem

Invitation to the Logic Seminar at the National University of Singapore

Date: Wednesday, 9 Nov 2016, 17:00 hrs

Room: S17#04-05, Department of Mathematics, NUS

Speaker: David Belanger

Title: An effective perfect-set theorem

URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html

Abstract: We gauge the difficulty of finding a perfect subtree in a tree
of a given Cantor-Bendixson rank. To simplify the analysis we introduce
half-derivative, and extend the definition of rank to include values of
the form n-and-a-half; each increase of one-half in the rank corresponds
to one added jump in the perfect-subtree problem.