this is quite long and written in plain english. I didn't skip forward to the "good bits", but I have to say the introduction was very clear for people entirely unfamiliar with the ideas http://bibliotecadigital.fgv.br/dspace/handle/10438/25696 -- Dave Täht CTO, TekLibre, LLC http://www.teklibre.com Tel: 1-831-205-9740