10–11 Jul 2023
Dipartimento di Matematica
Europe/Rome timezone

Continuous reducibility is a well-quasi-order on continuous functions with Polish 0-dimensional domains

10 Jul 2023, 09:30
45m
Aula Magna (Dipartimento di Matematica)

Aula Magna

Dipartimento di Matematica

Largo Bruno Pontecorvo 5 56127 Pisa Italy

Speaker

Raphael Carroy (Università di Torino)

Description

Given topological spaces $X,X',Y,Y'$, and two functions $f:X\to Y$ and
$f':X'\to Y'$, we say that $f$ reduces continuously to $f'$ when there is a
pair $(\sigma,\tau)$ of continuous functions such that $f=\tau\circ f'\circ\sigma$.
This quasi-order has first been introduced by Weihrauch in the context of Computable
Analysis at the beginning of the 1990s. It has recently received interest in
Descriptive Set Theory.
With Yann Pequignot, we proved that on the class of continuous functions with Polish
0-dimensional domains, there are no infinite antichains and no infinite strictly
descending chains for continuous reducibility. In other words, continuous
reducibility is a well-quasi-order on this class of functions.
I will give some context for this result and outline the proof.

Presentation materials