''As an example, we used a common ontology approach in mapping a set of
real estate databases some years ago. They all had the same domain, but
different naming and organization of tables. We first created a formal
ontology of real estate. Next we created a common database by
hand-compiling the ontology into a relational DB (Oracle).'' (01)
I am looking how a common ontology is to be applied to real estate matters.
As far as i learnt, good sources are rather few: The Ontology and Modelling
of Real Estate Transactions, published by Ashgate. Would much appreciate to
have access to your real estate ontology, if it is somehow documented. (02)
----- Original Message -----
From: "Adam Pease" <adampease@xxxxxxxxxxxxx>
To: "[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>
Sent: Thursday, May 03, 2007 7:36 PM
Subject: Re: [ontolog-forum] A "common basis" (04)
> We then
> mapped individual databases one at a time to the common DB. The first
> few DBs generated some small changes in the common DB and then it was
> smooth sailing. We had several dozen DBs mapped, integrated and running
> on the server backend, up 24/7, before the dot-com company ran out of
> It's anecdotal evidence only of course. We could have tried to
> create a data warehouse, bottom-up and that might have worked, although
> I think we then would have taken a lot of effort along the way to define
> precisely what each term meant, rather than doing it once, formally and
> ahead of time. This application couldn't have used pair-wise
> integration since the goal was a common DB, but one might imagine a
> distributed application where all the individual DB owners wanted to
> communicate. If they each had developed a pair-wise mapping between
> their DB and everyone else's it would have been the N^2 case, and
> clearly less efficient, and more error prone than creating a common
> Cassidy, Patrick J. wrote:
>> Actually, N^2 applies to the terms of ontologies also. The notion of
>> using existing equivalence of two terms in two ontologies to reduce the
>> effort of mapping might work, but only partly because:
>> (1) one has to know the equivalence mapping in all the other
>> ontologies -- not a trivial amount of work, and certainly not 0. If
>> there are a large number of ontologies, one has to inspect the
>> equivalence mappings of **every one**!! Try it, you won't like it.
>> (2) exact equivalence of intended meaning occurs in probably less
>> than half the terms in any two ontologies, and there is often meaning
>> overlap which is much more work to reduce
>> (3) *any* structural difference (difference in the relations) of two
>> terms in two ontologies will make them formally different (different
>> inferences) even if their intended meanings are the same.
>> Even if it seemed to work on a very small number of ontologies, it
>> is totally impractical when you get over 10. If you know of an example
>> where it has been done, let us know.
>> Patrick Cassidy
>> 260 Industrial Way West
>> Eatontown NJ 07724
>> Eatontown: 732-578-6340
>> Cell: 908-565-4053
>>> -----Original Message-----
>>> From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx
>>> [mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx] On Behalf Of
>>> Christopher Menzel
>>> Sent: Thursday, May 03, 2007 11:09 AM
>>> To: [ontolog-forum]
>>> Subject: Re: [ontolog-forum] A "common basis"
>>> On May 3, 2007, at 5:03 AM, Patrick Durusau wrote:
>>>> Adam Pease wrote:
>>>>> Hi Chris,
>>>>> Many thanks. I was really addressing a point that you weren't
>>>>> making, but which is all too common.
>>>>> I'm sympathetic to using SUMO for semantic interoperability.
>>>>> When I've done projects in that area, it has worked well. At the
>>>>> risk of stating the obvious, the advantage, at least in
>>> theory, of
>>>>> a common model over a federated approach is that one has mappings
>>>>> linear in the number of products needing integration, rather than
>>>>> potentially N^2.
>>>> I am glad you mentioned the "potentially N^2" issue. I have seen
>>>> that claim on a number of occassions but never with what I
>>>> considered a convincing explanation of why it must be so.
>>>> For example, assume that I have terms A, B, and C, all of which I
>>>> wish to say represent the same subject.
>>>> While I agree that it is possible to say A = B, A = C, B =
>>> C, ....,
>>>> isn't that an implementation choice?
>>>> In other words, if I have the mapping A = B and then later add B =
>>>> C, do I really need A = C? The effect of the first two mappings is
>>>> sufficient to reach the desired result.
>>>> Well, it should be noted that relying upon separate mappings does
>>>> result in a problem Steve Newcomb has faced with his topic map
>>>> implementation, that is how to determine when "all" the mappings
>>>> have been performed.
>>>> Ah, or is the N^2 claim based on a requirement that in order to
>>>> apply whatever inferences are available at A to C, a direct
>>>> is required? Still, that seems to be an implementation
>>> question and
>>>> not one of the actual mapping.
>>>> That is a particular methodology of mapping is being presumed. I
>>>> would assume once the mapping is complete, then the outcomes of
>>>> inferencing will be the same. Yes?
>>>> I have usually encountered the N^2 comment when a particular
>>>> vocabulary is being advocated. Noting that an implied mapping is
>>>> being peformed even by those who advocate a particular vocabulary,
>>>> but that the implied mapping is not (usually) available for others
>>>> to inspect or use. (The same can be the result using topic maps.
>>>> There is no requirement that a mapping in an implementation, which
>>>> may be commercial intellectual property, be disclosed. For
>>> the most
>>>> part, I think greater disclosure can potentially lead to more
>>>> interoperability. But, there are tradeoffs and reasonable people
>>>> will draw the line on disclosure at different places.)
>>> I don't think this is the issue Adam had in mind, Patrick. I
>>> Adam's N^2 remark doesn't have anything to do with the terms in a
>>> particular vocabulary (though there may in fact *be* an N^2 problem
>>> of some sort lurking there), but with the number of the languages
>>> used by the ontologies one is trying to integrate. Suppose we have
>>> four ontologies, each one written in a separate language --
>>> say Loom,
>>> Classic, SNEPS, and KL-1 (chosen because I have some appropriate
>>> graphics from a presentation I gave a few years ago :-) :
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