Re: SKOS exactMatch Inclusion - a question concerning ISSUE75

On 10/18/13 3:27 PM, Vladimir Alexiev wrote:
> As Johan points out, the SKOS spec is clear that nothing follows from exactMatch, nor the other way around.
> exactMatch is an equivalence property (transitive and symmetric), but it doesn't follow that it's "composable" with any other transitive property like broaderTransitive.
>
> I find this unfortunate. Here are some more considerations:
>
> - broadMatch allows you to graft a tree from one thesaurus to another.
> But exactMatch doesn't interlink the neighborhoods of the two concepts in any way :-(
> In that sense, it's WEAKER than broadMatch
>
> - SKOS allows "broader" cycles: http://www.w3.org/TR/skos-reference/#L2484. In such case I'd say that all the concepts in the cycle are exactMatch...
> Another way of saying the same is: if <c1 broader c2> and <c1 narrower c1> then c1 <exactMatch c2>
>
> - if <c1 foaf:focus o> and <c2 foaf:focus o> then I think should follow <c1 exactMatch c2>.
>    I proposed this half a year ago, Antoine called it a "co-denotation axiom" and found it reasonable.
> -- by the semantics of sameAs, the same consequence would follow from
>     <c1 foaf:focus o1> and <c2 foaf:focus o2> and <o1 sameAs o2>
>
> But like any other standard, SKOS is the result of some compromises: I guess the negators and doubters of such inferences won over in this case.
>
> However, this does not stop you from defining yourself such axioms in your dataset. E.g.
>     skos:broader owl:propertyChainAxiom (skos:broader skos:exactMatch).
> Or using the PROTON ontology:
>    skos:broader ptop:transitiveOver skos:exactMatch.
>
>
>

Yes, or to create sub-properties of skos:exactMatch that would do it (less interoperable option, but cleaner).

Other comments:
"SKOS allows "broader" cycles": I guess you meant "does not allow". The inference you describe could be interesting, but then the problem is that it would not allow to detect all the situations that are wrong. Take Simon Spero's notorious LCSH example. Many cycles are just bugs in the KOS conception, and thus would lead to completely wrong exactMatch statements if the inference was to apply.

The rule on foaf:focus looks indeed reasonable. But one could say that it's not really up to SKOS to define it, but FOAF :-)

Cheers,

Antoine

Received on Friday, 18 October 2013 16:53:46 UTC