User blog comment:Moooosey/Simple psi-- a fairly simple ocf/@comment-39541634-20191026192612

ψ(Ω)=ψ(ψ(ψ(ψ(...ψ(0)))))=ε0

And the limit is:

ψ(Ω+Ω+Ω+Ω+...)=εω

You can't go any higher (or even reach the limit itself) because there's no way to generate the ordinal Ωxω.

(this limit can be circumnavigated by adding more collapse functions and allowing ψ to use them. If done correctly, we will then have ψ2(0)=Ωxω and ψ(ψ2(0))=εω. This is precisely how Buchholz's OCF System works).