On the Π11‐separation principle
Antonio Montalbán · Mathematical logic quarterly · 2008
Abstract We study the proof‐theoretic strength of the Π11‐separation axiom scheme, and we show that Π11‐separation lies strictly in between the Δ11‐comprehension and Σ11‐choice axiom schemes over RCA0. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)