[om-list] Problems with Concept Relation Form

[Mark Butler]

Hello everybody,

    I have been attempting lately to cast my model completely in concept 
relation form, where there are no explicit concept attributes, just 
concepts and relations between concepts, maintaining the rule of only 
one true relation between any two concepts.   This normalization has 
some very attractive properties, but I have found it difficult to use.

The main problem is that natural language is full of attributes, which 
are always interpreted as noun expressions standing for the target 
concept, not the relationship itself - so I commonly deal with three 
intermediary concepts relating to two concepts and a relationship 
between them - two attributes and one relation.  For example, in an 
employee / employer relationship we have the attribute 
employee.employer, the set attribute employer.employees,  and the 
relationship between an employee and an employer.

 Those three things have very different senses that make it difficult to 
eliminate the first two and deal only with the latter.  For example, let 
us say I want to express the idea that an employer has three employees - 
I could make an evaluation of the employer->(employee class) 
relationship and and say it has cardinality three, but how do I clealy 
specify that I mean the employer has three employees rather than 
Employee has three employers.  That is where attribute concepts come in 
handy - if I evaluate the employer.employee attribute and say it has 
cardinality three, the ambiguity goes away.  Anytime I talk about a 
relationship on the other hand, the polarity of the relationship and the 
way each statement refers to it is criticial.

Time and space predicates present a similar issue - If I want to express 
something about the state of an object as of a particular time, I am 
really creating a new concept, an object state, and expressing a 
proposition about that rather than the object itself.  The problem is 
that like an attribute, an object state does not map 1:1 to the 
relationship between an object and a specific time.  That particular 
(O,t) relationship could have other aspects which make it more than just 
an object state.  However, in order to refer to the object state, I need 
a concept that stands for the object state and nothing else.  This can 
be done in pure CRF, but the number of objects required to represent a 
simple statement quickly gets out of hand.

My preliminary conclusion is that using nominative concepts like 
attributes and states will be more efficient than representing 
everything in terms of pure class/object concepts and relations between 
them, initial appearance to the contrary. 

 - Mark