[foaf-dev] beyond foaf:mbox_sha1sum

Dan Brickley danbri at danbri.org
Sat Dec 19 20:31:23 CET 2009

On Sat, Dec 19, 2009 at 8:14 PM, Richard Cyganiak <richard at cyganiak.de> wrote:
> On 19 Dec 2009, at 18:05, Gregory Williams wrote:
>>>> 3. perhaps remove the owl:InverseFunctionalProperty typing (this will
>>>> help with OWL DL compatibility too)
>>> +1. In practice, doing IFP smushing on this property according to the
>>> OWL spec is a recipe for disaster anyway [1].
>> I'm not convinced about this "recipe for disaster" stuff. The pedantic web
>> page you link to suggests to me that people should just be careful when
>> using this term, not that they shouldn't use it.

'Disaster' is overkill, but over-simplistic data merging strategies
will get people into trouble. There are lots and lots of circumstances
in which naively believing RDF found on the Web will get you into
trouble; this is just one of many.

> I didn't say that people shouldn't use the term. I said that you shouldn't
> do IFP smushing according to the OWL spec on the term. Because if you do,
> you will get horrible results. Several of my colleagues in DERI have tried
> it and can tell entertaining war stories. You need a blacklist of known-bad
> values, plus a bunch of additional heuristics, if you want to do smushing on
> this property.

If the list is short, it might be worth including in the spec?

Actually - related - I was thinking to make a wiki page for each term
in the spec. Could go there..

Another related problem: OWL IFP logic includes any language tags that
happen to be in scope. So if my mbox hash is mentioned in an rdf/xml
file and eg inherits a french or japanese xml:lang, it won't match the
one in my file.

>> The fact that some sites don't properly protect against exporting the hash
>> of an empty string (where an email address should have been) doesn't strike
>> me as a reason that the sites that do use it properly shouldn't benefit from
>> its current use.
> Removing the IFP flag from the FOAF spec doesn't stop anyone from
> benefitting from the current use of the property. It just means that an
> off-the-shelf OWL reasoner won't attempt to do the smushing.



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