Re: D2RQ and Revelytix semantics

Thanks!  I think this is largely correct.  I was working on simple examples 
myself but you've done a lot more than I have. :)  




________________________________
From: Juan Sequeda <juanfederico@gmail.com>
To: Richard Cyganiak <richard@cyganiak.de>; Alex Miller <alexdmiller@yahoo.com>; 
public-rdb2rdf-wg@w3.org
Sent: Mon, July 26, 2010 3:51:24 PM
Subject: D2RQ and Revelytix semantics

Hi Richard, Alex and all

I took the liberty of analyzing D2RQ and Revelytix mapping language and compare 
it to the semantics that Marcelo and I have defined in Datalog [1]. (BTW, 
Marcelo defined the semantics of Datalog in the wiki also!) 

Marcelo and I are still working on this so you can see a draft of what we are 
doing in the following google doc (once we are done, we will put it on the 
wiki.... tables in the wiki are a pain!)

https://docs.google.com/document/pub?id=1APTqD2lJLRjwV6gmPKqDRqC3aT8bozHF0udIXndMNWQ 


Please forgive me if I butchered the mapping language.

Quick conclusion:

- Both mapping languages are very similar
- Both mapping languages have the semantics established as 
Database-Instance-and-Schema Mapping [1] (there is a definition of Classes and 
Properties). There is no way to formally prove this because both languages don't 
have existing defined semantics (right?)
- Revelytix language has different ways of saying the same thing for sake of 
query optimization ( right?). (I personally believe this is something we should 
avoid. Language and implementation details should be separate... just look at 
SQL)

Looking forward to Alex's presentation tomorrow!


[1] http://www.w3.org/2001/sw/rdb2rdf/wiki/Database-Instance-Only_and_Database-Instances-and-Schema_Mapping


Juan Sequeda
+1-575-SEQ-UEDA
www.juansequeda.com