Patrick, (01)
Patrick Cassidy wrote:
>
> But I haven't seen examples of the problem you refer. Can you provide
> examples that were actually caused by multiple inheritance rather than
> simple errors in some instance of assigning subtype per se?
> (02)
Maybe it is necessary to say what is meant by an error. Multiple
inheritance could cause *problems* if one needed to divide the ontology
into multiple modules. I think that is why Alan Rector et al. developed
their normalisation technique [1] in the OpenGalen project. It doesn't
say that you can't use multiple inheritance but rather that you should
build a kind of taxonomy "backbone" with only single-inheritance and
then build upon it. (03)
Jakub (04)
[1] Alan L Rector, Modularisation of Domain Ontologies Implemented in
Description Logics and related formalisms including OWL
http://www.cs.man.ac.uk/~rector/papers/Modularisation-normalisation-rector.pdf (05)
> Pat
>
> Patrick Cassidy
> MICRA, Inc.
> 908-561-3416
> cell: 908-565-4053
> cassidy@xxxxxxxxx
>
>
>> -----Original Message-----
>> From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx [mailto:ontolog-forum-
>> bounces@xxxxxxxxxxxxxxxx] On Behalf Of Alan Ruttenberg
>> Sent: Monday, May 12, 2008 11:16 PM
>> To: bfo-discuss@xxxxxxxxxxxxxxxx; Phillip Lord
>> Cc: [ontolog-forum] ; obo-relations@xxxxxxxxxxxxxxxxxxxxx
>> Subject: Re: [ontolog-forum] [bfo-discuss] Re: Heterarchy & Hierarchy,
>> oh my my
>>
>> On May 6, 2008, at 11:54 AM, Phillip Lord wrote:
>>>>>>>> "Alan" == Alan Ruttenberg <alanruttenberg@xxxxxxxxx> writes:
>>> Alan> I've seen the disadvantages of multiple asserted
>>> inheritance when
>>> Alan> reviewing, e.g. the Cell ontology in OBO, where it was
>>> demonstrated
>>> Alan> (by the authors) that it was quite easy to find mistakes of
>>> the sort
>>> Alan> where all of the properties described in the definition of
>>> (multiple,
>>> Alan> and transitive) superclasses were not true of instances of
>>> the class
>>> Alan> in question. Regarding (c) what is perhaps being referred
>>> to is that
>>> Alan> if one practices "normalization" in the sense that Alan
>> Rector
>>> Alan> proposes [1] then the component single inheritance
>>> ontologies from
>>> Alan> which more complex terms are constructed are more likely to
>>> be able to
>>> Alan> be reused by other projects. Certainly that's the intention
>> of
>>> Alan> creating and using PATO. I've found the exercise of factoring
>>> Alan> definitions in this manner is often helpful and is
>>> conducive to
>>> Alan> helping the sorts of people I work with think carefully when
>>> Alan> constructing ontologies.
>>>
>>> I think that we need to be clear here; there is a fundamental
>>> distinction
>>> between normalisation as according to Alan Rector and to the idea
>>> of single
>>> inheritance is a correct reflection of reality.
>> I think I've been clear on this. What I consider interesting is that
>> the same conclusions about the pragmatics of ontology construction
>> arise from two different approaches. For me, since I have respect for
>> the purveyors of these two approaches, this strengthens the case that
>> this is a good way to go about doing things.
>>
>>> While you are correct that allowing multiple inheritance increases
>>> the risk of
>>> some common errors, it also allows modelling that is not possible
>>> otherwise;
>>> in particular it can be used to avoid a combinatorial explosion of
>>> terms.
>> Example?
>>
>>> My take; single inheritance can be easier and simpler sometimes,
>>> but not always;
>> Curious about the not always. And not sure about the easier or
>> simpler either. "I would have written a shorter letter if I had
>> time", etc. But I think it leads to better quality results.
>>
>>> using a computationally amenable languages and normalisation allows
>>> you to get some of the advantages of both.
>> +1 on that one.
>>
>> -Alan
>>
>> (the *other* Alan R ;-)
>>
>>> Phil
>>>
>>>
>>>
>>> ps, I started of writing this email referring to Alan Rector as
>>> "Alan". Then I
>>> had to correct it to "Alan R" to disambiguate from you. Then again.
>>> Eech.
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> (06)
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