Re: WOWG: first language proposal

Frank.van.Harmelen@cs.vu.nl wrote:
>Looking forward to a discussion on our proposal

I have a few questions about the language proposal that probably
stem from my lack of familiarity with Frame Representation Systems.
A quick scan through the seemingly relevant parts of the Karp paper
didn't reveal any new answers, so I am asking the group.

Limited Cardinalities:
>3.Notice that the "light" idiom limits cardinality constraints to the 
>values 1 and "greater than 1" (as mathematicians say: "0,1,infinity" :-) 

Why?  Is this all that the Frame idiom typically provides?


Properties -vs- Slots:

The walkthrough includes the following examples:

>SubPropertyOf(hasMother, hasParent)

What are the semantics associated with SubProperty?  I 
assume at least: 
  Any valid value of the SubProperty 
  must also be a valid value of the Parent property.
But is there more?

>PrimitiveClass(Animal,
>                slot(hasParent, range=Animal, required)
>                slot(hasMother, range=Female, required, singlevalued))

The language description says:
"Slot definitions place restrictions on properties in classes."

Are slot definitions also able to define properties, as seems to occur 
in this example?  My larger question is, what exactly are properties?
Are they partially defined relations (slots)?  If so, how much about them 
must be defined for them to be reusable (in slots or in SubProperty 
definitions)?

-Evan

Received on Tuesday, 19 March 2002 14:56:19 UTC