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Precision of qualified involvements
From Provenance WG Wiki
luc 7 Nov 2011 (off list):
6. It would be good to write that unqualified involvement is "unprecise". When we assert used(pe,e), it could be because of QualifiedUse(pe,e,t1,role=r1) and QualifiedUse(pe,e,t2,role=r2). So, used(pe,e) gives a *lower bound* on the number of actual uses.
In light of this discussion, I feel we could come to the following proposals. 1. Subsection on derivation would define two relations only. wasDerivedFrom: linked to 1 activity only wasBasedOn (used to be called wasEventuallyDerivedFrom): linked to unspecified number of activities wasDerivedFrom is a special case of wasBasedOn in the following sense: wasDerivedFrom(e2,e1) implies wasBasedOn(e2,e1) Both wasDerivedFrom and wasBasedOn are non-transitive. Indeed, we can find examples where transitivity does not make sense. 2. A new section introducing a transitive relation computed as a transitive closure over: wasControlledBy wasComplementOf wasBasedOn Not sure what its names, but should capture the idea of being in the history of the subject. What do you think? Simon, wasBasedOn/wasEventuallyDerivedFrom: is it right to say that the only difference between wasBasedOn and wasDerivedFrom is that the latter is associated to one and only one activity, while the former may be associate to many (and their number may be unknown). Luc
Yes, as you say, I think the only difference between wasDerivedFrom and wasBasedOn is that the former is used where you wish to express what activity the derivation was due to, while the latter implies nothing about activities (and so may be due to many).