Proof-theoretic dilator and intermediate pointclasses

There are two major generalizations of the standard ordinal analysis: One is Girard’s ${\mathrm{\Pi }}_2^1$-proof theory in which dilators are assigned to theories instead of ordinals. The other is Pohlers’ generalized ordinal analysis with Spector classes, where ordinals greater than ${\omega }_1^{\mathsf{C}\mathsf{K}}$ are assigned to theories. In this paper, we show that these two are systematically entangled, and ${\mathrm{\Sigma }}_2^1$-proof theoretic analysis has a critical role in connecting these two.