Re: [Use Case] ETRI-UC1: Filling the holes of OWL ontology

Ans.
>
>With rules, it's trivial to describe "uncle" relation in a general way,
>with which all the 'uncle' relations between relevant individuals can be
>inferred. Take the following OWL sentences and a rule for example.
>
>ObjectProperty(hasSibling Symmetric)
>Class(Human partial
>   restriction(hasSibling allValuesFrom(Human)))
>Class(Man partial Human)
>Class(Parent partial
>   Human
>   restriction(hasChild someValuesFrom(Human)))
>Individual(Sam type(Human))
>Individual(John type(Man))
>Individual(Bob type(Human) value(hasChild Sam) value(hasSibling John))
>
>Uncle001: hasUncle(?x,?y) :- hasChild(?z,?x) ^ hasSibling(?z,?y) ^ Man(?y)
>
>Now, you don't have to enumerate any "uncle" relation instances as they are
>derived by the added rule. The above rule can be used to infer that "Sam has
>an uncle John", which saves many sentences if it were to be described in OWL
>only. Moreover, you don't need all the unnatural tweaks that were introduced
>into the OWL ontology to express "uncle" relation.

umm, well, yeah sort of - there is an issue that if I tell you
  Uncle(John, Mary) it is unclear to me that you could conclude from 
the rules above that
    hasChild(?z, Mary)
(or that it would be inconsistent for Mary to be in a class of people 
who have no parents) without grounding the assertions (i.e. using 
some sort of safe reasoning)

I'm just trying to get people to be very careful about what they are 
claiming -- when we move to RL, we need to be careful about what is 
required for grounding variables (i.e. the rule above would be safe 
if you made it
Uncle001: hasUncle(?x,?y) :- hasChild(?z,?x) ^ hasSibling(?z,?y) ^ 
Man(?y) ^ Person(?z) ^Person(?y)

This open vs. closed world reasoning can get tricky, and even in 
closed worlds, you have to be careful exactly what you are claiming.
  -JH

-- 
Professor James Hendler			  Director
Joint Institute for Knowledge Discovery	  	  301-405-2696
UMIACS, Univ of Maryland			  301-314-9734 (Fax)
College Park, MD 20742	 		  http://www.cs.umd.edu/~hendler
(New course: http://www.cs.umd.edu/~hendler/CMSC498w/)

Received on Tuesday, 13 December 2005 02:55:30 UTC