Two Interesting Quotes
by Bijan Parsia
Going through the OWLED 2007 papers, two quotes about OWL 1.1 jump out at me. The first is from Kent Spackman, of SNOMED fame:
Without a solid DL foundation, the Semantic Web would have remained largely irrelevant to health care terminology standardization. Even so, the initial version of OWL was developed without taking adequate account of features of DL that had already been used in both the GALEN [6] and SNOMED [7] efforts. The development of OWL 1.1 eliminated one of the most significant barriers to use of OWL for SNOMED, since it permits the identification of tractable sublanguages capable of handling the size and complexity of SNOMED [8]. Although adding property chain inclusion axioms was reportedly the most difficult step in developing OWL 1.1 [9], this was essential. Without it, adoption of OWL by the SNOMED community would have required awkward workarounds with their attendant complications and complexities – effectively killing movement in that direction. With it, we have a clear path to using OWL 1.1 for further development and integration with other biomedical ontologies. [emphasis added]
It’s always nice to get a super-positive endorsement, esp., one that, given the high density of praise, is remarkably hype-free. (Whether you agree with Kent’s identification of representational requirements is a separate issue.) One really nice bit of his singling out property chain inclusions (think of them as a generalization of transitivity and subpropertying) is that they highlight the synergy between the extensions to OWL in OWL 1.1 and the proposed fragments. Various versions of SNOMED (and other biomedical ontologies) fall into the logic EL++, which has very nice computational properties. However, they also use complex role inclusions, which put them outside the OWL 1.0 part of EL++. Thus we see extending and sensible subsetting marching happily hand in hand.
The second quote is a table:
This table (in spite of the confusing “CWA” column…I think they mean that the features are used in so called “closure axioms”) is really helpful for seeing what various OWL 1.1 features get you. This paper also had one of the few well described use of rules (in particular, of a DL Safe “SWRL” rule) in an OWL ontology. In my coding of features requested/offered in OWLED 2007 papers it was clear that “rules”, in some sense, were very important, but it was typically unclear what sort of rules would suffice. Indeed, it’s interesting that in the standardization session, DL Safe SWRL rules did not end up in “standards track”. I think this is because of the confusion surrounding “rules” (which is a very unhelpful term) and modeling in OWL. This paper gave clear indication of what the ontologists lacked, what they wanted, and what they actually used (they did check their entailments with KAON2). It’s hard to overstress the value of such clarity.
