quick note on Derivation

Hi,

for reference, I just left a note on the wiki on Derivation (http://www.w3.org/2011/prov/wiki/ConceptDerivation), which includes a 
link to a recent tutorial on "Provenance and Causality" presented at TAPP'11, June 2011 by Dan Suciu:
http://www.ics.forth.gr/~gregkar/tapp/papers/Day%201%20-%20Session%201%20-%20Provenance%20and%20Causality/tutorial-causality-slides-Suciu.pdf   
(so yes, it's a DB-centric view)
see the refs on slide 3 are interesting

-Paolo