My web page www.grsampson.net/RLeafAnc.html gives references to journal articles on the leaf-ancestor evaluation technique and a link to software implementing it, which might be of interest.
Regards,
Geoffrey Sampson
Prof. Geoffrey Sampson MA PhD FRSA FBCS CITP FHEA
Department of Informatics, University of Sussex
Falmer, Brighton BN1 9QJ, England
www.grsampson.net +44 1273 678525