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Re: comment on /2001/11/13-RDF-Query-Rules/ re 'single arc languages'

From: Uche Ogbuji <uche.ogbuji@fourthought.com>
Date: Mon, 24 Mar 2003 19:40:10 -0700
To: "Eric Prud'hommeaux" <eric@w3.org>
cc: Libby Miller <Libby.Miller@bristol.ac.uk>, Dan Brickley <danbri@w3.org>, www-rdf-rules <www-rdf-rules@w3.org>
Message-Id: <E18xeME-0000kY-00@borgia.local>

> There is a query defined at the top of a query/rules survey [1] which
> i use to compare the different protocol query languages. If you
> express this query in versa, I'll have what I need to drop it into the
> survey.

OK.  I think this is the one Libby asked me about a couple of weeks ago.  I 
answered:

"""If I understand the original query rightly, then perhaps:

Define a namespace mapping wsdl -> http://schemas.xmlsoap.org/wsdl/service

distribute(
 type(wsdl:service),
 '.'
 'distribute(. - wsdl:hasPort -> *,
   ".",
   "distribute(. - wsdl:binding -> *,
     \".\",
     \". - wsdl:name -> *\"
   "
 )'
)
"""

We're considering some core functions that would make this a lot more concise.

Also I caught these notes:

"No observed single arc languages support variables"

Versa supports varables:

$resource - rdfs:label -> *

"This leaves them unable to answer the specific query
represents(?x ?x) "What lawyers represent themselves?"

Versa can handle this just fine:

filter(type(x:Lawyer), ". - x:represents -> .")

Again, I am not convinced that there is any query that the SQL-ish languages 
can handle that Versa can't, and I get the sense that there are queries that 
Versa can handle that SQL-ish languages cannot.

BTW, the 4Suite Versa implementation supports all the above examples.


-- 
Uche Ogbuji                                    Fourthought, Inc.
http://uche.ogbuji.net    http://4Suite.org    http://fourthought.com
Universal Business Language (UBL) - http://www-106.ibm.com/developerworks/xml/l
ibrary/x-think16.html
EXSLT by example - http://www-106.ibm.com/developerworks/library/x-exslt.html
The worry about program wizards - http://www.adtmag.com/article.asp?id=7238
Use rdf:about and rdf:ID effectively in RDF/XML - http://www-106.ibm.com/develo
perworks/xml/library/x-tiprdfai.html
Keep context straight in XSLT - http://www-106.ibm.com/developerworks/xml/libra
ry/x-tipcurrent.html
Python Generators + DOM - http://www.xml.com/pub/a/2003/01/08/py-xml.html
Using SAX for Proper XML Output - http://www.xml.com/pub/a/2003/03/12/py-xml.ht
ml
SAX filters for flexible processing - http://www-106.ibm.com/developerworks/xml
/library/x-tipsaxflex.html
Received on Monday, 24 March 2003 21:42:57 GMT

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