Friendly amendment to rif:subClassOf

</chair>
Here is a hopefully friendly amendment to the proposal to add a 
rif:subClassOf relation to BLD:

If we just say that <rif:subClassOf rdfs:subPropertyOf 
rdfs:subClassOf> I think it goes part of the way in addressing the 
chief concern of Jos and Dave (which is, as I understand it, that we 
shouldn't add yet another subclass relation to the semantic web).

This would make it clear that we are not really creating something 
new, just imposing a restriction on something already there - in 
particular all rif:subClassOf relations are also rdfs:subClassOf 
relations, but not the reverse, and we would say that rif:subClassOf 
is not reflexive, only holds between classes, etc.

Less the new name, this is what Jos proposed - to define a suitably 
restricted subset of RDFS that would be usable for RIF.  I think the 
new name (rif:subClassOf) helps to make it clear that we do not intend 
the full rdfs semantics, rather than "hiding" that in the semantics.

<chair>

-Chris

Chris Welty wrote:
> 
> 
> Michael Kifer wrote:
>> Rumblings on why we need classification terms in RIF
>> (and why RDF's vocab should not be used)
>> ===================================================
>>
>> Two issues: whether we should define facilities for expressing some data
>> model stuff and whether we should use rdfs for this.
>>
>> Rationale:
>>    If we do not have such constructs then everybody will be inventing 
>> their
>>    own. People will not be able to specify any part of their data 
>> model in RIF
>>    which will reduce the usefulness of RIF as an exchange language.
>>
>> Why it is not good to use RDF's facilities to define class hierarchies.:
>>    RDF is a foreign language whose semantics is burdened with 
>> non-standard
>>    things. For instance, subclass is reflexive.
>>
>>    This is bad because not every language out there uses reflexive 
>> subclasses.
>>    For instance, if we map, say, FLORA-2's subclass relationship to 
>> RDFS's then
>>    in the translation (RIF) the query whether foo is a subclass of foo 
>> will
>>    say "yes" but in FLORA-2 it will say "no".
> 
> </chair>
> No, no - translating flora2:subclass into rdfs:subclass would be 
> incorrect, because they have different semantics.  For me, this is the 
> stronger point in favor of rif:subclass - since so few systems use the 
> rdfs semantics for subclass, very few systems when translating into RIF 
> would use it in their translations.
> 
> Same for below.  You shouldn't translate ilog:subclass into 
> rdfs:subclass.  So, in fact, as far as we know, only rdfs based systems 
> would ever use rdfs:subclass when translating through rif, and everyone 
> else would have to invent their own.
> <chair>
> 
>>
>>    Let's look at some other examples, like ILOG. From my limited 
>> experience
>>    with it, I remember that it uses Java as its data model. So, suppose
>>    there is a class foo in ILOG, which comes from Java. An ILOG set of
>>    rules must not derive "foo sub foo" because this is not true in the 
>> data
>>    model. However, it we translate Java subclass relationship into
>>    rdfs:subclassOf then the resulting RIF translation should generate 
>> "foo
>>    sub foo". (In truth, as I recall, ILOG does not have "sub" in the 
>> heads
>>    of the rules, but it is easy to imagine that next year ILOG is 
>> extended
>>    with something like a query facility. Then their stock will plummet
>>    because their rule sets will not be faithfully exchangeable through 
>> RIF
>>    :-)
> 
> 
> 

-- 
Dr. Christopher A. Welty                    IBM Watson Research Center
+1.914.784.7055                             19 Skyline Dr.
cawelty@gmail.com                           Hawthorne, NY 10532
http://www.research.ibm.com/people/w/welty

Received on Wednesday, 15 August 2007 13:20:06 UTC