Re: Cross-ontologies reasoning

[Drew McDermott: ]
    [Francis McCabe]
       Notwithstanding the technologies being discussed, *translation* 
    between ontologies is about as tractable in the general case as mapping 
    between English and Japanese.

This assessment is overly pessimistic.  We're not talking about
translating Japanese literature into English.  In most cases the
differences between ontologies fall into categories such as these:

* One ontology represents a concept as a class, the other as a property

* One ontology makes fine distinctions about a concept; the other uses
   a broader brush.

* One ontology uses a predicate with n arguments where the other uses
   a similar predicate with n+1.  The missing argument must be deleted
   or inferred somehow.

* and so forth

Translating back and forth can be done by straightforward deductions.

-----

I agree, provided that the language in which these ontologies are 
expressed is expressive enough. Examples like these are exactly what 
have motivated the design for SCL, which imposes no syntactic 
constraints which require some a-priori division into 'class' versus 
'thing' or n-ary versus m-ary relations. All relations are 
potentially variadic (can take any number of arguments.)  Then you 
can write things like

Married(x y) iff exists z Married (x y z)

or even, if you prefer

Married(x y) iff exists z Married(z) & wife(z)=x & husband(z)=y

which allows you to add as many other 'arguments' to a marriage as you like.

All of this can be done in a purely first-order language: the 
cross-ontology 'difficulties' are mostly artifacts of poor formalism 
design, where syntactic constraints have been lifted out of logic 
textbooks without considering the needs arising from information 
transmission over networks. We can do better than this.

Pat Hayes

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