User blog comment:SuperSpruce/T array function stuck at Gamma 0/@comment-35470197-20190614223407

If you want to collapse an ordinal which can be expressed as a non-trivial sum, you need to give a nest using the rest of the rightmost term in the expression of the sum.

For example, with respect to Buchholz's OCF, \(\psi(\Omega^{\Omega}2) = \psi(\Omega^{\Omega} + \Omega^{\Omega})\) is the limit of the following sequence if I am correct: \begin{eqnarray*} \psi(\Omega^{\Omega} + \Omega^{\omega}) \\ \psi(\Omega^{\Omega} + \Omega^{\omega^{\psi(\Omega^{\Omega} + \Omega^{\omega})}}) \\ \psi(\Omega^{\Omega} + \Omega^{\omega^{\psi(\Omega^{\Omega} + \Omega^{\omega^{\psi(\Omega^{\Omega} + \Omega^{\omega})}})}}) \\ \vdots \end{eqnarray*} I am not good at explicit computation, and hence I might be wrong.