[seek-kr-sms] Semantic Web Rule Language and GrOWL
Bertram Ludaescher
ludaesch at ucdavis.edu
Sat Apr 23 08:11:56 PDT 2005
Hi Serguei:
I haven't followed SWRL very closely, but as far as I can see, this is
all about syntax for Horn rules (which have a well-defined syntax
since quite a while). For example this is a SWRL rule:
Implies(Antecedent(hasParent(I-variable(x1) I-variable(x2))
hasBrother(I-variable(x2) I-variable(x3)))
Consequent(hasUncle(I-variable(x1) I-variable(x3))))
and this is the "actual" Horn rule (in Prolog syntax):
hasUncle(X1,X3) :-
hasBrother(X2,X3),
hasParent(X1,X2).
Interestingly, SWRL call their syntax "abstract". I think it's not
abstract but concrete. Also interesting: the Prolog rule is
1. more human readable and
2. just as easily machine readable as the SWRL one (possibly even more
easily).
Then why is SWRL needed?
But the fact that tools such as RACER will support SWRL syntax is of
course noteworthy. What other rule syntaxes do they allow?
Bertram
Serguei Krivov writes:
> I have heared that RACER based extension to SWRL is coming out in near
> future, which perhaps render some practical value to SWRL. I have looked
> carefuly at resent SWRL proposal:
>
> http://www.daml.org/2003/11/swrl/
>
> All SWRL rules are conjunctive and have form antecedent => consequent, where
> both antecedent and consequent are conjunctions of atoms of the form x:C or
> (x,y):R, where C is class description, R is role name, x, y are either
> variable or individual names.
>
>
> In this case GrOWL -Query could be accurately extended to GrSWRL without
> adding any new symbols for operators. Here are the first and the last rule
> examples from RSWL proposal, given at
> http://www.daml.org/2003/11/swrl/examples.html
>
>
>
>
> Implies(Antecedent(hasParent(I-variable(x1) I-variable(x2))
> hasBrother(I-variable(x2) I-variable(x3)))
> Consequent(hasUncle(I-variable(x1) I-variable(x3))))
>
>
>
>
>
>
>
> Implies(Antecedent(Artist(I-variable(x))
> (restriction(artistStyle
> maxCardinality(1)))(I-variable(x))
> Style(I-variable(y))
> creator(I-variable(z) I-variable(x)))
> Consequent((restriction(style/period
> maxCardinality(1)))(I-variable(z))))
>
>
> Hope that this was entertaining,
> Serguei
>
>
>
>
>
>
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>
> <p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
> font-family:Arial'>I have heared that RACER based extension to SWRL is coming
> out in near future, which perhaps render some practical value to SWRL. I
> have looked carefuly at resent SWRL proposal:</span></font></p>
>
> <p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
> font-family:Arial'><a href="http://www.daml.org/2003/11/swrl/">http://www.daml.org/2003/11/swrl/</a></span></font></p>
>
> <p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
> font-family:Arial'>All SWRL rules are conjunctive and have form a</span></font><span
> class=syntax>ntecedent</span> => <span class=syntax>consequent, </span>where
> both <span class=syntax>antecedent</span> and <span class=syntax>consequent</span>
> are conjunctions of atoms of the form x:C or (x,y):R, where C is class
> description, R is role name, x, y are either variable or individual names.</p>
>
> <pre><font size=2 face="Courier New"><span style='font-size:10.0pt'> </span></font></pre><pre><font
> size=2 face="Courier New"><span style='font-size:10.0pt'>In this case GrOWL –Query could be accurately extended to GrSWRL without adding any new symbols for operators. Here are the first and the last rule examples from RSWL proposal, given at http://www.daml.org/2003/11/swrl/examples.html</span></font></pre><pre><font
> size=2 face="Courier New"><span style='font-size:10.0pt'> </span></font></pre>
>
> <p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
> 12.0pt'><img border=0 width=444 height=156
> src="cid:image001.jpg at 01C547ED.A78F3A10"></span></font></p>
>
> <pre><font size=2 face="Courier New"><span style='font-size:10.0pt'>Implies(Antecedent(hasParent(I-variable(x1) I-variable(x2))</span></font></pre><pre><font
> size=2 face="Courier New"><span style='font-size:10.0pt'> hasBrother(I-variable(x2) I-variable(x3)))</span></font></pre><pre><font
> size=2 face="Courier New"><span style='font-size:10.0pt'> Consequent(hasUncle(I-variable(x1) I-variable(x3))))</span></font></pre>
>
> <p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
> 12.0pt'> </span></font></p>
>
> <p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
> 12.0pt'> </span></font></p>
>
> <p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
> 12.0pt'><img border=0 width=423 height=157
> src="cid:image002.jpg at 01C547ED.A78F3A10"></span></font></p>
>
> <pre><font size=2 face="Courier New"><span style='font-size:10.0pt'>Implies(Antecedent(Artist(I-variable(x)) </span></font></pre><pre><font
> size=2 face="Courier New"><span style='font-size:10.0pt'> (restriction(artistStyle maxCardinality(1)))(I-variable(x))</span></font></pre><pre><font
> size=2 face="Courier New"><span style='font-size:10.0pt'> Style(I-variable(y))</span></font></pre><pre><font
> size=2 face="Courier New"><span style='font-size:10.0pt'> creator(I-variable(z) I-variable(x)))</span></font></pre><pre><font
> size=2 face="Courier New"><span style='font-size:10.0pt'> Consequent((restriction(style/period maxCardinality(1)))(I-variable(z))))</span></font></pre><pre><font
> size=2 face="Courier New"><span style='font-size:10.0pt'> </span></font></pre><pre><font
> size=2 face="Courier New"><span style='font-size:10.0pt'> </span></font></pre><pre><font
> size=2 face="Courier New"><span style='font-size:10.0pt'>Hope that this was entertaining,</span></font></pre><pre><font
> size=2 face="Courier New"><span style='font-size:10.0pt'>Serguei</span></font></pre>
>
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