Assigns to each consistent theory T an ordinal |T| measuring its proof-theoretic strength — the least α such that T ⊬ TI(α). |PA|=ε₀, |ATR₀|=Γ₀.
Assigns to each consistent theory T an ordinal |T| measuring its proof-theoretic strength — the least α such that T ⊬ TI(α). |PA|=ε₀, |ATR₀|=Γ₀.