1 citations · 1 across the 7 of their papers we have counts for
13 papers
Kreisel-Lévy-type theorems for Kripke-Platek and other set theories
Shuangshuang Shu, Michael Rathjen
We prove that, over Kripke-Platek set theory with infinity (KP), transfinite induction along the ordinal is equivalent to the schema asserting the soundness of KP, where…
No speedup for geometric theories
Michael Rathjen
Geometric theories based on classical logic are conservative over their intuitionistic counterparts for geometric implications. The latter result (sometimes referred to as Barr's t…
Extensional realizability for intuitionistic set theory
Emanuele Frittaion, Michael Rathjen
In generic realizability for set theories, realizers treat unbounded quantifiers generically. To this form of realizability, we add another layer of extensionality by requiring tha…
Ackermann and Goodstein go functorial
Juan P. Aguilera, Anton Freund, Michael Rathjen +1
We present variants of Goodstein's theorem that are equivalent to arithmetical comprehension and to arithmetical transfinite recursion, respectively, over a weak base theory. These…
Well-Ordering Principles in Proof Theory and Reverse Mathematics
Michael Rathjen
Several theorems about the equivalence of familiar theories of reverse mathematics with certain well-ordering principles have been proved by recursion-theoretic and combinatorial m…
Minimal bad sequences are necessary for a uniform Kruskal theorem
Anton Freund, Michael Rathjen, Andreas Weiermann
The minimal bad sequence argument due to Nash-Williams is a powerful tool in combinatorics with important implications for theoretical computer science. In particular, it yields a…