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[protege-owl] Modeling change, source, uncertainty, contradiction?
matthew.williams at cancer.org.uk
Wed Aug 22 07:36:11 PDT 2007
This looks more like RDF reification.
You may have more luck looking at something like Jena.
Johann Petrak wrote:
> Matt Williams wrote:
>> As a very simple approach to modelling time, you could use
>> time-interval-valid versions of the ontology. Not pretty, but might be
> For my purpose, I would be more interested in searchability than
> deductability. In other words, I do not want to make deductions based
> on time -- it would be sufficient to find properties of instances
> that are valid at a specific time. (So time would not be an issue
> for classes, just for instances)
> Naively I want an attribute "valid during" for each property/relation
> between instances.
> More generically I want several attributs: "valid during", "source"
> The only thing I would need to do is to get the value of these
> attributes out of the knowledge base and to search for triples
> where these attributes match a specific pattern.
>> DL ontologies will not handle conflicting information. To do that, you
>> need to use a defeasible formalism. There is a little bit of work on
>> ontologies & defeasibel reasoning.
>> I have used argumentation & ontologies; there's a paper at
>> http://acl.icnet.uk/~mw/WillliamsHunterICTAI07.pdf which also has
>> references to the other approaches.
> Thank you for the reference. I am not sure I need it at such a
> complex level though, since I do not need a reasoner to
> come up with sets of entailed or conflicting facts.
> I think it would be sufficient for me to be able to model
> something like
> "source A indicates instanceX Rel1 instanceY"
> "source B indicates instanceX notRel1 instanceY"
> or put differently
> instanceX Rel1-withattr: from source A instanceY
> So it comes down to attatching searchable arbitrary attributes
> to properties/relations again.
> Could it be that I am missing something totally elementary
> here because it seems that should be something that is needed
> all the time?
>> If you want to discuss this in more detail, email me off-list.
>> Johann Petrak wrote:
>>> I am pretty new to using Ontologies for knowledge represenation so
>>> most of the tutorials and examples I have seen only are about
>>> modeling some consistent set of unchanging facts.
>>> However, in real word situations it is often necessary to deal
>>> with knowledge or information that has one of the following
>>> * a fact might change over time. More exactly, a property
>>> might be valid during some period of time but not another.
>>> Is it possible to model this in OWL ontologies and if yes,
>>> what are common design patterns to do it?
>>> * The fact that some instance has some property might be
>>> known based on sources A and B but might not be confirmed
>>> from source C. More problematic, it might contradict
>>> information from source D. So instead of some fact just
>>> "existing" we would like to model that it exists
>>> "according to source A" but "not confirmed by source C"
>>> and "not, according to source D"
>>> Is it possible to model this?
>>> * Sometimes it would be useful to attach a level of belief
>>> to a fact. E.g. some instance having some property might
>>> be likely but not certain.
>>> These things are probably differently hard to model, if at
>>> My biggest concern at the moment is change over time: for
>>> most applications where I need some knowledge representation
>>> it would be extremely important to be able to know that
>>> e.g. some name was used during a certain time or that some
>>> property existed during a certain period but not another.
>>> I would be thankful for any hints you could give me or
>>> any papers or sources you could point out where these
>>> issues are discussed.
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