A wordy proof of a combinatorial lemma that arose in operator theory
Bruck and Baillon proved a long-standing open problem in operator theory
by reducing it to a combinatorial lemma, that they proved using
the maple package EKHAD. Here I show an alternative proof, much nicer
and shorter, using the powerful `Schutzenberger methodology'.
.dvi version (for previewing)
Checker's Report (by Mireille Bousquet-Melou).