[foaf-dev] beyond foaf:mbox_sha1sum

Richard Cyganiak richard at cyganiak.de
Sat Dec 19 21:18:02 CET 2009

On 19 Dec 2009, at 19:31, Dan Brickley wrote:
>>>> +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,

Smushing 60k+ people into a single über-node is the closest you can  
come to a disaster in FOAF-land ;-)

>> 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?

The tech report written up by Aidan and colleagues [1] mentions two  


The first is the hash of "mailto:", the second is the hash of the  
empty string.


[1] http://www.deri.ie/fileadmin/documents/DERI-TR-2009-07-28.pdf

> 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.
> Yup...
> Dan

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