Re: Higher Order Reasoning

On Jan 28, 2004, at 3:35 AM, Suresh Kumar M wrote:

> Hi
> 	I came across this line while reading the manual, that "PowerLoom
> supports limited form of higher order reasoing". Can somebody give
> pointers to what exactly are these higher order features. It would
> be great if  sample statements are given.

The main higher-order features that are supported are via 
FRAME-PREDICATES, the HOLDS relation and the IST relation.  The 
simplest form of higher-order reasoning would be something quantifying 
over a particular relation.

For example:

    (retrieve all (exists ?c (and (concept ?c) (holds ?c ?z))))

Here we are retrieving all objects for which there is a concept of 
which they are an instance.  We are existentially quantifying over 
concepts, and are thus second order.  Note that this will return 
essentially all objects in the KB.  In this particular case it isn't 
really an interesting query, but with some other constraints it may 
turn out to be useful.

We term the reasoning limited, since (for performance reasons among 
others) PowerLoom will not by itself want to generate all relations to 
try in a HOLDS clause.

The frame predicates are used to make assertions about relations and 
instances and may be considered to be a weak form of 2nd-order 
reasoning.


>
>
> with regards,
> Suresh Kumar M
>
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