Re: [BLD] Frame without slot/value pair?

> 
> Michael Kifer wrote:
> > 
> > [...]  Formulas like t[] are also useful. If they are allowed, their
> > semantics is that the object t exists (without testing any of its
> > properties).
> 
> Hmmm. I wonder how useful it is really.
> 
> In order to check the existence of object t, you have to denote it in 
> some way: How do you denote an object without either asserting or 
> checking its existence already in the process (thus removing any need to 
> check it further)?

What does one have to do with the other??

It is like asking, "why is it useful to test that a table is not empty?
Shouldn't one first create a table and put tuples into it?


> Actually, the only use I found for a formula like t[] is to allow the 
> retraction of an individual without having to allow retracting TERMs as 
> well as ATOMICs (in RIF-PRD). But that's a different can of worms...

You found a use in what context? In PRD or BLD? In logic programming-style
dialects this is undoubtedly useful.


	--michael  


> Christian
> 
> 
>