On Wed, February 5, 2014 09:35, Mike Bennett wrote: (01)
> On 02/02/2014 21:40, Kingsley Idehen wrote:
>> On 2/2/14 10:11 AM, Mike Bennett wrote:
>>> The problem with using owl:sameAs is that you have immediately
>>> changed the nature of your model: from a model of concepts to a model
>>> of words. That is, from an ontology to a vocabulary. (02)
Agreed. (03)
>> When you put Linked Data in the mix its about terms rather than words
>> i.e., terms being words that have the duality of denotation and
>> reference baked in. (04)
Words standardly have both. However, NL words normally have multiple
denotations. (05)
>> Thus, you can use owl:sameAs to express
>> coreference in ABox oriented statements about entities. (06)
> I find the term "term" a little slippery in its many applications.
> Presumably then in Linked Data "term" refers to a label (with a URI)
> that denotes an individual in the world or a fact about that individual? (07)
Different Linked Data "terms" denote individuals, classes, and relations. (08)
>> For TBox or RBox oriented descriptive statements (for entity types and
>> relation types, respectively) you have owl:equivalentClass and
>> owl:equivalentProperty, respectively. (09)
> Right - I was thinking of owl:equivalentClass. There's good reason to
> use this when asserting that a class in one OWL ontology represents the
> same concept as one in someone else's OWL ontology (though you end up
> bringing in the assertions from that other ontology so you'd better be
> sure it really is the same concept!). (010)
If you are importing an OWL ontology, you can use the concepts from that
ontology, you needn't create your own copy. You only need to use
owl:equivalentClass, owl:equivalentProperty, and owl:sameAs if you are
importing multiple ontologies which share concepts, but not terms for them. (011)
> What I was resisting was the
> tendency to use OWL to make what appear to be TBox assertions about the
> existence of a class, where that class is tied to one natural language
> word, and another class is tied to another natural word in the same
> ontology which is synonymous, and the synonymy is dealt with using an
> assertion that the two classes mean the same thing (have the same
> extension). When is that a useful thing to do and when is it the wrong
> thing to do? (012)
It does not seem useful to me. (013)
> I can see for example that if one were doing text extraction from a
> corpus of unstructured data, it would be useful to have an ontology
> which defines all the words individually (014)
Sure. Each word is an individual. Each individual word has one (or more)
spellings, frequent misspellings, pronunciations, and standard
transformations
(declinations, conjugations, etc.). Each individual word also has a mapping
to one or more classes, individuals, or relations. Phrases (short word
lists)
also have mappings to such meanings. (015)
A text extraction system should express these mappings. (016)
> with equivalent class assertions, (017)
No. The words are individuals, not classes. They should not map to each
other (unless you want to model different spellings as different words),
but to meanings. (018)
> whereas if one wanted to reason over concepts (for example,
> to calculate financial exposures across financial instruments and
> counterparty hierarchies) then you really would not want to do that. (019)
Agreed. (020)
-- doug foxvog (021)
> ... (022)
> Best regards,
>
>
> Mike (023)
>>> As long as it's clear which one of those you are doing, that's fine.
>>> But I find an ontology of concepts to be far more useful than a
>>> vocabulary of words.
>>
>> Horse for courses :-)
>>
>>>
>>> The only place I would use owl:sameAs is when mapping between
>>> ontologies that have concepts with the same meanings.
>>
>> See comment above. (024)
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