[SCL] Re: (SCL) Getting a move on

[Chris Menzel]

On Wed, Dec 18, 2002 at 10:05:30AM -0600, Pat Hayes wrote:
> Lets argue about sequence vars. I bet your company doesnt need full 
> CL seqvars, equivalent to an infinitary logic, right? Do you ever 
> need to write something like
> 
> (forall (?x) (exists (@y)....))
> 
> What do you do with it when you've written it??

Pat, 

Granted, the full semantics and proof theory of CL seqvars is
infinitary, but one may not need all of that power and still find a need
for seqvars just in virtue of using a variably polyadic predicate.  Your
question seems to run roughshod over that possibility.  For example,
suppose you are using a variably polyadic "eats" predicate, and you have
a constraint that there is always someone eating but you don't
necessarily have or care about the information about what is eaten when,
where, etc.  Thus, in your database at any given time, you might have
any of the following:

(eats pat)
(eats bill eggs)
(eats chris tofu noon)

but all you need to verify is that someone eats.  (exists (?x) (eats ?x)
won't do the job except in the first case.  (exists (@x) (eats @x))
expresses what we want in all cases.

> We havn't begun to think seriously about the meta-extension. 

I have. :-)

-chris

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