Unicity of prefLabel. Was: W3C SKOS Reference Last Call (3 days left in comment period)

Hi Magnus,

I have some difficulties with your proposal.

If SKOS is what I believe it is (a data structure to support 
applications when linking users needs to computerized ressources), you need:
1) for the computer: precise identification (the unambiguous "about" of 
each concept)
2) fot the user: a precise to choose the right concept.

The data must allow to build choices so the user can identify the 
concept (s)he desires. If you have:
"Do you need:
 * football
 * football
 * football"
the user is nowhere.

With thesauri (which are term based, not concept based), it was usual to 
add a disambiguation information between parenthesis. This is 
straigthforward and clear:
* football (sport equipment)
* football (sport)
* football (social phenomenon)

If one wanted to automate the generation of disambiguation information, 
it was also possible to use the scheme name: the PrefLabel had then to 
be unique within a (micro-)thesaurus. This is approximatively what SKOS 
proposes and it is not as good as "human written" disambiguated labels.

With your proposal, we may remain with nothing left: if the unicity rule 
is relaxed, we need to describe a (simple?) mechanism to specify the 
"user side" disambiguation data. From my point of view, we have to keep 
the first "S" of "SKOS".

Further considerations about disambiguation:
* users tend to be limited in their ability of abstraction and in their 
knowledge of specialized concepts.
* classification creators tend to use top concepts linked to readily 
known needs, to existing scientific domains and bottom concepts rooted 
in the "daily" reality of the practitionners. The problem is with middle 
of the hierarchy where often lies "artificial" concepts created for 
classification purposes.
* disambiguation must provide the user with something he can 
discriminate (to choose a "football", you must know the difference 
between "equipement", "sport" and "social phenomenon").
* Selecting disambiguation information is therefore more difficult than 
it seems and I doubt perfection can be obtained automatically.

My suggestions:
* Keep the unicity rule for now;
* Transform the uniticy rule on prefLabel to unicity of 
prefLabel+disambiguation information
* Design a way to automate disambiguation based on very simple rules 
(for instance "SchemeLabel" or "TopConceptLabel" or "BroadInSchemeLabel")
* Provide "manual" ways to disambiguate:
    ** "contextLabel" to specify a piece of text to disambiguate an 
ambiguous PrefLabel
    ** or a new semantical relation "uniqueUnder" which would link an 
ambiguously labelled concept to one of its broader concepts well known 
by most users

Have a nice day!

Christophe

Magnus Knuth a écrit :
>
> Hello,
>
> I know I am a little late.
>
> We are working with SKOS for a while now using it so long mainly for 
> topic hierarchies. I just read the Reference and Primer once again and 
> found some points to mention.
>
>  * in the SKOS Primer (2008-08-29) Chap. 2.2.1 last sentence should 
> tell "..., it is therefore recommended that no two concepts in the 
> same KOS be given the same preferred lexical label --in any two given 
> languages-- __in any given language__." (might be a typo)
>
> Well, we cannot apply this recommendation, since we sometimes have 
> different concepts with identical prefLabel, e.g. ex:football_(sport) 
> and ex:football_(ball) both having skos:prefLabel "football", i.e. we 
> don't want to disambiguate these concept by their prefLabel but by 
> further characteristics as their definition or altLabel.
> Same would apply, when you collect alternative definitions for a term 
> resulting in different concepts, e.g. the medical term "sepsis" is 
> defined in various variants from "inflammatory infection" over "blood 
> poisoning" to "infection with organ dysfunction", and medics use it in 
> such various manner.
>
> So please leave it an informal recommendation.
>
>  * in the SKOS RDF (2008-05-xx and 2008-08-29) #prefLabel the comment 
> should tell therefore "No two concepts in the same concept scheme 
> --may-- __should__ have the same value for skos:prefLabel in a given 
> language." (according RFC 2119)
>
> Kind regards
>
> Magnus.
>
>
> Alistair Miles schrieb:
>> Dear all,
>>
>> There are only 3 days left in the Last Call comment period for the
>> Simple Knowledge Organization System SKOS Reference. For more
>> information see the Last Call announcement at:
>>
>>   http://lists.w3.org/Archives/Public/public-esw-thes/2008Sep/0001.html
>> Thanks to those who have already provided valuable feedback.
>>
>> Kind regards,
>>
>> Alistair.
>>
>>