Abstract: 
In this formalization, we develop an implementation of the Goodstein
function G in plain λcalculus, linked to a concise, selfcontained
specification. The implementation works on a Churchencoded
representation of countable ordinals. The initial conversion to
hereditary base 2 is not covered, but the material is sufficient to
compute the particular value G(16), and easily extends to other fixed
arguments. 
BibTeX: 
@article{Goodstein_LambdaAFP,
author = {Bertram Felgenhauer},
title = {Implementing the Goodstein Function in λCalculus},
journal = {Archive of Formal Proofs},
month = feb,
year = 2020,
note = {\url{http://isaafp.org/entries/Goodstein_Lambda.html},
Formal proof development},
ISSN = {2150914x},
}
