15 citations · 26 across the 27 of their papers we have counts for
4 papers · 1 filter
An order-theoretic characterization of the Howard-Bachmann-hierarchy
Jeroen Van der Meeren, Michael Rathjen, Andreas Weiermann
In this article we provide an intrinsic characterization of the famous Howard-Bachmann ordinal in terms of a natural well-partial-ordering by showing that this ordinal can be reali…
Well ordering principles and bar induction
Michael Rathjen, Pedro Francisco Valencia Vizcaino
In this paper we show that the existence of omega-models of bar induction is equivalent to the principle saying that applying the Howard-Bachmann operation to any well-ordering yie…
Goodstein revisited
Michael Rathjen
Inspired by Gentzen's 1936 consistency proof, Goodstein found a close fit between descending sequences of ordinals epsilon_0 and sequences of integers, now known as Goodstein seque…
Indefiniteness in semi-intuitionistic set theories: On a conjecture of Feferman
Michael Rathjen
The paper proves a conjecture of Solomon Feferman concerning the indefiniteness of the continuum hypothesis relative to a semi-intuitionistic set theory.