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Re: ISSUE-26: SimpleExtension proposal

From: Daniel Rubin <rubin@med.stanford.edu>
Date: Tue, 29 May 2007 07:49:22 -0700
Message-Id: <6.2.5.6.2.20070529073905.0477aa78@med.stanford.edu>
To: Guus Schreiber <schreiber@cs.vu.nl>,SWD WG <public-swd-wg@w3.org>

Guus,
I have a few comments on this. See below:

At 06:25 AM 5/29/2007, Guus Schreiber wrote:

>ACTION: Guus revise his ISSUE-26 proposal to account for other 
>options [recorded in http://www.w3.org/2007/04/24-swd-minutes.html#action07]
>All,
>
>Below is my SimpleExtension proposal for isue 26 (relations between 
>labels). I haven't had time to check the syntax of the examples or 
>put it on the Wiki.
>Guus
>
>
>SKOS ISSUE-26 Relations between Labels: "SimpleExtension" Proposal
>
>This is a proposal for resolution of SKOS ISSUE-33.
>0. Summary
>
>The proposal extends SKOS with the possibility to define a term as a
>resource, such that statements can be made about it. To this end we
>introduce the class skos:Term plus the corresponding properties (pref,
>alt, hidden) which link a concept to a term.
>The property skos:relatedTerm can be used to express relations between
>terms. Applications will typically specialize this to define
>particular lexical relations.
>The proposal ensures OWL DL compatibility.
>
>1. Vocabulary
>
>The proposal introduces the following new vocabulary:
>
>  skos:Term

Can we get the English definition of a skos:Term?

Also, in terms of naming "Term," this is find if SKOS restricts 
itself to modeling thesauri, but for people who are creating 
ontologies to represent things in reality, "entity" would be better 
than "term". In my biomedical use cases, I have examples of this.

>  skos:prefTerm
>  skos:altTerm
>  skos:hiddenTerm
>
>  skos:relatedTerm

Can we get English definitions of each of these?


>2. Axiomatic Triples
>
>The following triples are added:
>
>  skos:Term rdf:type rdfs:Class.
>
>  skos:prefTerm rdf:type rdf:Property.
>  skos:prefTerm rdfs:domain skos:Concept.
>  skos:prefTerm rdfs:range skos:Term.
>
>  skos:altTerm rdf:type rdf:Property.
>  skos:altTerm rdfs:domain skos:Concept.
>  skos:altTerm rdfs:range skos:Term.
>
>  skos:hiddenTerm rdf:type rdf:Property.
>  skos:hiddenTerm rdfs:domain skos:Concept.
>  skos:hiddenTerm rdfs:range skos:Term.
>
>  skos:relatedTerm rdf:type rdf:Property.
>  skos:relatedTerm rdfs:domain skos:Term.
>  skos:relatedTerm rdfs:range skos:Term.

In terms of naming properties, it is often helpful to adopt a naming 
convention such as a "has" prefix to distinguish names of properties 
from classes. How about naming these hasPrefTerm, etc?


>3. Semantic Conditions
>
>* A skos:Concept has at most one skos:pretTerm relation
>
>    skos:prefTerm rdf:type owl:FunctionalProperty.
>
>* A skos:Concept must be the subject of at least one one skos:prefLabel or
>  skos:prefTerm triple.
>    NOTE: there seems to be no reason to forbid mixing of label and
>    class approach. So the "or"is not an exclusive or.

What are the characteristics of the other properties--altTerm, 
hiddenTerm, and relatedTerm? Are any transitive (I'm particularly 
wondering about relatedTerm)?

>4. Consistent Examples
>
>EXAMPLE 1
>
>The example below shows two terms for a concept, where one term is defined
>as the acronym of the other term.
>  ex:who    rdf:type skos:Concept;
>    skos:prefTerm ex:who1.
>    skos:altTerm ex:wh02
>  ex:who1    rdf:type skos:Term;
>    rdfs:label "World Health Organization"@en-us;
>    rdfs:label "Wereldgezondheidsorganisatie"@nl.
>  ex:who2    rdf:type skos:Term;
>    rdfs:label "WHO"@en.
>
>  ex:acronymOf    rdf:type rdf:Property;
>    rdf:subPropertyOf skos:relatedTerm.
>
>  ex:who2 ex:acronymOf who1.

In this example, did you mean to say "ex:who  rdf:type  skos:Term"?

>
>
>5. Inconsistent Examples
>
>All triples that obey the constraints posed by the RDF/OWL definitions
>are consistent.
>
>
>6. Entailment Rules
>
>DISCUSSION: should we have an entailment rule that says something
>like:
>
>  for every <x>Term statement (where x can be either pref, alt or
>  hidden) tools are allowed to assert a <x>Label triple for each of
>  the rdfs:label statements of the object of the <x>Term statement.
>
>So from example 1, applications derive  the following additional triples:
>
>  ex:who    skos:prefLabel "World Health Organization"@en-us;
>    skos:prefLabel "Wereldgezondheidsorganisatie"@nl;
>    skos:altLabel "WHO"@en.
>
>DISCUSSION: should the inverse also be true? E.g should applications be
>allowed to derive the following:
>  ex:who    skos:prefLabel "World Health Organization"@en-us;
>    skos:prefLabel "Wereldgezondheidsorganisatie"@nl;
>    skos:altLabel "WHO"@en.
>
>  entails
>
>  ex:who
>    skos:prefTerm      [a skos:Term        rdfs:label "World Health 
> Organization"@en-us;
>        rdfs:label "Wereldgezondheidsorganisatie"@nl];
>    skos:altTerm      [a skos:Term        rdfs:label "WHO"@en].
>
>NOTE: the difference with example 1 is here that the instances of
>skos:term are represented as blank nodes.
>NOTE: to express these entailments it might be easier to define a
>superproperty for the both the Label and the Term properties.
>
>7. Syntactic Constraints
>
>@@todo
>
>
>8. Discussion
>
>The objective of this proposal is allow term relations, while
>preserving compatibility with the label approach.
>The main alternative would be to drop the semantic constraint on the
><x>Label properties to be an owl:DatatypeProperty. This would make the
>following example consistent:
>
>  ex:who    rdf:type skos:Concept;
>    skos:prefLabel ex:who1.
>  ex:who1    rdf:type skos:Term;
>    rdfs:label "World Health Organization"@en-us.
>
>even in combination with:
>
>  ex:who    skos:prefLabel "World Health Organization"@en-us;
>
>One can view this of the MinimalFix proposal but has two
>disadvantages: - ambiguity wrt the range of the skos:<x>Label properties
>- incompatibility with OWL DL, as it is not possible to define the
>label properties as either an objector a datatype property.
>The SimpleExtension proposal preserves OWL DL compatibility.
>The entailment rules mentioned under 6 are meant to preserve
>interoperability between vocabularies that use different approaches to
>represent lexical labels.
>
>
>
>
>
>--
>Vrije Universiteit Amsterdam, Computer Science
>De Boelelaan 1081a, 1081 HV Amsterdam, The Netherlands
>T: +31 20 598 7739/7718; F: +31 84 712 1446 Home page: 
>http://www.cs.vu.nl/~guus/
Received on Tuesday, 29 May 2007 14:51:40 UTC

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