[SCL] Re: [CL] editing questions on CL std

[Pierluigi Miraglia]

CycL has had seqvars at least since 2001 (when I found out, and I was
there! ;)  But they can only be in the last arg position. So one
still can't replace all the rules that Bill intended to refer to.

One reason is that such rules are not frequently found in Cyc is that
backchaining on unbound pred vars is (or was last I checked) a very
dark inference sinkhole.

--- Bill Andersen <andersen at ontologyworks.com> wrote:
> 
> On Apr 17, 2005, at 2354, Pat Hayes wrote:
> 
> >> Pat,
> >>
> >> How many projects that use KIF are actually using seqvars?
> >
> > I gather that OntologyWorks use them, or something with equal 
> > expressive power (an LP subset supporting recursion.)
> >
> > John, if this is the start of a campaign to remove seqvars,
> please 
> > don't go there. You have had over three years of opportunity to 
> > suggest changes like this to the CL design. At some point, we
> just 
> > have to take some decisions.
> 
> We use them -- heavily.  Example:
> 
> (forall (p q)
>    (implies
>      (subsumedBy p q)
>      (implies
>        (p ...x)
>        (q ...x))))
> 
> This and a number of other applications.  CycL, the last time I saw
> it, 
> didn't have seqvars, and the result was that they had to write n 
> versions of every such axiom which is, if nothing else, a pain.
> 
> Thanks for the heads-up, Pat!
> 
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--
Pierluigi 
plmiraglia yahoo com