Oberseminar "Mathematische Logik" - Renrui Qi

This talk is about the proof of the independence of existence of Laver's function with Peano arithmetic, which has seen no progress for more than 30 years since it was proposed. We also propose a new notation for computable ordinals from this proof, which is seems very strong. Also, we propose a sequence of new computable ordinal notations that seems to require (slightly weaker than) I1 to prove its well-orderedness. 

Zoom (Teilnahme-Link auf Anfrage an Anton Freund)