On 2/11/2013 11:08, Steve Ray wrote:
Scott,
Thanks for telling me about Property Paths - I didn't know you could
do that.
The property path operator * allows you to walk up (or down) class
hierarchies, e.g.
?class rdfs:subClassOf* ?restriction .
?restriction owl:allValuesFrom ?allValuesFrom .
would find all restrictions above ?class.
Furthermore, there is a potentially useful built-in function
spif:walkObjects. See swa.spin.ttl -> swa:localRangeAtClass for some
sophisticated example. This function supports scenarios where you need
to walk up the class hierarchy until you find the *nearest*
allValuesFrom restriction.
HTH
Holger
Your query won't do what I need - I'm trying to traverse all three relations
(subclassof, "superclassof", and allValuesFrom) from a given starting point,
in an effort to expose "orphan classes" that aren't connected to all the
others (except through owl:Thing of course), which I will do by differencing
my results from your results. (I hadn't mentioned needed to also traverse
the sub- and super- relations.)
Meanwhile, I believe I have done it, using three pairs of functions (one
pair for allValuesFrom, one for subclassof, and one for "superclassof"), and
using smf:isBound as a termination test for functions that don't return
(because they contain empty results, or because they encounter a previously
visited class). Seems to work fine - I'd be happy to share if you are
interested, or if you believe I don't have to resort to recursion.
- Steve
Steven R. Ray, Ph.D.
Distinguished Research Fellow
Carnegie Mellon University
NASA Research Park
Building 23 (MS 23-11)
P.O. Box 1
Moffett Field, CA 94305-0001
Email: [email protected]
Phone: (650) 587-3780
Cell: (202) 316-6481
Skype: steverayconsulting
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Scott Henninger
Sent: Sunday, February 10, 2013 4:11 AM
To: TopBraid Suite Users
Subject: [topbraid-users] Re: Traversing a graph
Steve; I believe the following query will work for you:
SELECT ?avfCls
WHERE {
?cls rdfs:subClassOf ?x .
?x owl:allValuesFrom ?avfCls .
}
...and with SPARQL 1.1 Property Paths this can be shortened to
SELECT ?avfCls
WHERE {
?cls rdfs:subClassOf / owl:allValuesFrom ?avfCls .
}
Keep in mind that the graph pattern matching does the iteration for you.
Recursive solutions are rarely needed.
-- Scott
On Feb 8, 5:41 pm, "Steve Ray (CMU)" <[email protected]> wrote:
I have been working on writing a graph-traversal algorithm using
SPARQL queries and function calls, and it occurs to me that someone in
this group might have already done this. I am trying to transitively
follow all of the owl:allValuesFrom restrictions from a given starting
class. The two challenges are that this involves a double-hop from one
class to the next (rdfs:subClassOf followed by owl:allValuesFrom), and
that such a traversal typically has many cycles (i.e. closed loops)
within it, most trivially with bidirectional relations.
If anybody has done this, either elegantly or otherwise, I'd love to
see your solution. Meanwhile, I will share with this group when and if
I get mine to work.
- Steve
Steven R. Ray, Ph.D.
Distinguished Research Fellow
Carnegie Mellon University
NASA Research Park
Building 23 (MS 23-11)
P.O. Box 1
Moffett Field, CA 94305-0001
Email: [email protected]
Phone: (650) 587-3780
Cell: (202) 316-6481
Skype: steverayconsulting
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