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F2F1 Minutes Session 5
This is part of F2F1 Minutes
OWL Working Group Meeting Minutes, 07 December 2007
DRAFT. Currently Under Review
Contents
See also: IRC log
- Scribe
- Jeff Pan
(Scribe changed to Jeff Pan)
Datatypes
Slides for this session: Media:sattler-f2f1.pdf
Uli is presenting
OWL DL does not support user defined datatypes
Uli Sattler: users want to represent intervals
... and comparisons
... in OWL DL no inverse functional datatype properties
... not to mention composite keys (not even OWL Full supports this)
Boris Motik: we might want to keep the unit mapping out of TBox
Jeremy Carroll: second
Sebastian Brandt: there are real world examples
... that we need datatype mapping in the TBox
Bijan Parsia: both needed
Uli Sattler: we have examples of seeing class subsumption checking based on datatype constraints
Carsten Lutz: it is difficult to choose one standard set, e.g. covering integers, rational, +, *, ...
Uli Sattler: as many as possible
Jeremy Carroll: each simple example is easy
... but have concern on having all of them, which makes it hard
Sebastian Brandt: combining DL and data values are important and useful, there are many tasks that you could not solve if you treat datatypes externally
Alan Ruttenberg: do we want to detect the problematic cases?
Jeff Pan: there are existing works on datatype groups, a mechanism is already there, see http://www.websemanticsjournal.org/papers/20050811/document.pdf
... even in OWL DL, freely combinations are not possible, e.g. transitive properties are not allowed to used in number restrictions
Jeremy Carroll: what happen if data in the user databases having both integers, rationals + and * ...
Boris Motik: we need some datatype profile
Carsten Lutz: second boris point
Jeff Pan: two points: 1) profiling is a good idea, there have been work there such as datatype groups
... and we could provide a list of feasible datatype groups
2) if users have integers, rationals + and *, we could simply have type promotion, promoting integers into rational, and it is still decidable, see http://www.w3.org/TR/swbp-xsch-datatypes/ and http://www.w3.org/TR/xpath20/#promotion
Alan Ruttenberg: maybe we could have a stroll poll on this
Bijan Parsia: we all agree that some sort of datatypes are needed, no matter in OWL or RIF
... many of our cases cannot be addressed by RIF
Jeremy Carroll: transitive issue is different
Jeff Pan: besides Racer, an extension of FaCT (FaCT-DG) also supports n-ary and datatype groups
Uli Sattler: we could have some more general proposal, rather than specific ones
Bijan Parsia: we don't have to require all our implementors to implement everything, so we should be flexible somehow
Uli Sattler: the 4th point: easy keys
Markus Krötzsch: in foaf people use b-nodes rather than individuals, so the easy key might not solve the foat problem
stall poll 1: many +1, no -1, four 0
s/stall/straw
straw poll 2: (all) +1
straw poll 3 (about 2-b): many +1, two (conditional) -1, six 0
straw poll 4 (n-ary datatype): twelve +1, six -1, five 0
straw poll 5(easy key): 22 +1, one -1
Boris Motik: one profile proposal: a set of default profiles and allowing users to have arbitrary profiles
Another go, boris' profile: a fixed set of profile and also allowing people to define their owl profiles
alanr's proposal: a fixed set of profile
straw poll on profiling on datatype: eighteen +1, four 0
scribers should clean up yesterday's minutes by next telecon
(by IanH and no objections)