Models of the Weak König Lemma
Tin Lok WONG · Annals of the Japan Association for Philosophy of Science · 2017
This paper surveys the model-theoretic aspects of two topics initiated by Kazuyuki Tanaka related to the Weak König Lemma: self-embedding, and conservativity for sentences of the form ∀X ∃!Y θ(X,Y), where θ(X,Y) is an arithmetical formula. It includes a few recent developments and proof sketches.