[om-list] Relation Aspects

[Mark Butler]

Relation Aspects

As I mentioned before, I have implemented my data model using a rule 
that there is only one relation between any two concepts.  The relation 
itself is an abstraction - that nature of the relation is represented by 
various evalative predicates from various commentators about the 
relation.  Some might deny the existence of the relation all together, 
some might affirms some aspects, but not others, and so on.

This has some very interesting consequences that I haven't entirely 
become used to yet.  For example, I might be tempted to create a class 
called Belief that is an sub class of Relation.  However, in order to 
guarantee that only one relation exists between any two concepts, the 
relation object cannot be characterized prematurely.  Characterizing a 
relation as only a belief jumps the gun, because that relation may have 
other aspects besides belief.   

A relation between any two persons may have several independent aspects, 
including parenthood, friendship, belief, love, trust, loyalty, and so 
on.  All of those aspects have to be treated independently of the 
relation object itself under the rule I have adopted. That doesn't mean 
that the real world relation between two entities does not have 
objective character, but rather that this rule requires strict 
neutrality regarding the initial aspects and character of concepts and 
relations.

In order to process common aspects of relations, I have created a new 
helper class hierarchy rooted in Relation_Aspect.   A relation aspect is 
very similar to a one of the definitions of the word relationship.   
Relation aspects (or role specific relationships) are not normalized 
model components in my scheme, so I do not store them as persistent 
entities.   Nonetheless, they are very useful things to materialize at 
runtime, when you want the answer to questions like "How likely is it 
that X is the father of Y?"

 - Mark


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