User blog comment:Moooosey/Simple psi-- a fairly simple ocf/@comment-43798125-20191026225036/@comment-35470197-20191102001136

Oops, you are not abbreviating psi's as psi, but introducing a new function psi. Sorry for the careless reading. I guessed that psi is the traditional abbreviation of psi_0 in this community, and hence I only read thedefinition of psi_0.

Anyway, psi_m(α) = ε_{ζ_{m-1}+1+α} for any positive integer m and ordinals α < ζ_m, and hence psi_m(α) = ζ_m for any positive integer m and ordinals ζ_m ≦ α ≦ W. Similarly, psi(α) = ζ_ω for any ζ_ω≦α ≦ W if I am correctly reading it this time.