Taxonomy Is Hard

Re:Taxonomy Is Hard by flanked-evergl on Tuesday November 01, 2022 @08:54AM (#33420502)

If you tag using RDF[1] and use OWL[2] to define both the tag name and values then it really works pretty well. And with some entailment rules[3] you can even define rules that tags on folders becomes tags on items inside them, or you can just solve this with a bit more complex SPARQL query [4][5].

For an example of where such a system is used, see:

- WikiData[6]: They use RDF but they don't use OWL, they have a similar though less formal way of defining types, and then entailment has to be encoded in SPARQL queries.

- schema.org[7]: Uses RDF and also provide OWL specifications.

[1]: https://www.w3.org/TR/rdf11-primer/ [2]: https://www.w3.org/TR/owl2-primer/ [3]: https://www.w3.org/TR/rdf11-mt/#entailment-rules-informative [4]: https://www.wikidata.org/wiki/Wikidata:SPARQL_query_service/... [5]: https://www.wikidata.org/wiki/Wikidata:SPARQL_query_service/... [6]: https://www.wikidata.org/wiki/Wikidata:Main_Page [7]: https://schema.org/

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Re:Taxonomy Is Hard by PaulHoule on Tuesday November 01, 2022 @09:42AM (#33421114)

What I realized the other day is that the property restrictions in OWL are a lot like the options you see on a typical search interface, say,

https://ropercenter.cornell.edu/ipoll/

It is hidden in plain site, for instance if you read this

https://www.w3.org/TR/owl-ref/#Restriction

you might not realized that there are some other axioms documented elsewhere in the standard that let you query on "less than", "greater than", "matches a regex", etc. Instead of fighting with Protege or writing turtle you should be able to compose queries out of restrictions plus complements, unions and intersections the way you snap together a program in Scratch, but somehow the idea that OWL works as a query language (logically define a class in terms of its properties) had eluded people completely.

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