Hans Koch, Alain Schenkel, Peter Wittwer
Computer-Assisted Proofs in Analysis and Programming in Logic: A Case Study
(171K, plain TeX)
ABSTRACT. In this paper we present a computer-assisted proof
of the existence of a solution for the Feigenbaum equation
phi(x)=phi(phi(lambda*x))/lambda.
There exist by now various such proofs in the literature.
Although the one presented here is new, the main purpose of this paper
is not to provide yet another version,
but to give an easy-to-read and self contained introduction
to the technique of computer-assisted proofs in analysis.
Our proof is written in Prolog (Programming in logic),
a programming language which we found to be well suited for this purpose.
In this paper we also give an introduction to Prolog,
so that even a reader without prior exposure to programming
should be able to verify the correctness of the proof.