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Re: Views on the outcomes of F2F

From: Lee Feigenbaum <lee@thefigtrees.net>
Date: Tue, 10 Nov 2009 16:45:59 -0500
Message-ID: <4AF9DF17.5070402@thefigtrees.net>
To: Andy Seaborne <andy.seaborne@talis.com>
CC: Steve Harris <steve.harris@garlik.com>, SPARQL Working Group <public-rdf-dawg@w3.org>
Andy Seaborne wrote:
> 
> On 10/11/2009 20:18, Steve Harris wrote:
>  > We're explicitly not chartered to do assignment - if that makes sense -
>  > somewhat tortured English. We voted on a list of things to be in the
>  > charter, and assignment was on the list that didn't make it.
>> You could regard it as syntactic sugar for subselect + project
>> expressions, but that doesn't appear to be what Holger is after, and
>> it's a little sophisitic to argue that IMHO.
> 
> We have now have had feedback that the assumption that SELECT expression 
> syntax is not sufficient.  We can respond to comments.
> 
> I believe Holger is asking for nothing more than syntactic sugar.
> Jeremy's syntactic conversion from LET to SELECT expressions shows what 
> they want and it's a syntactic rewrite even SPARQL syntax to SPARQL syntax.

I couldn't follow the transformation. Can you explain it, please? I'm 
trying to figure out if it matches what is implemented in Open Anzo or not.

> We know LET->SELECT and SELECT->LET as syntatic transforms.. There is no 
> new functionality (it does not change the algebra at all); it's all in 
> the syntax to algebra translation step, which is what I consider 
> syntactic suger.
> 
> I understand the comment as a request to make it easier to use by 
> exposing the assignment part of AS without the project interactions - 

Is this the "Extend" operator in the FPWD? I'm having trouble 
understanding the definition (and, again, checking if this is consistent 
with my implementation).

One of the things that I'm trying to evaluate in looking at 
TopQuadrant's request is whether this is as simple as they and you 
claim. Part of trying to evaluate that is seeing if the various 
implementors really have implemented the same thing. Another part is 
figuring out if different people have different expectations about what 
LET would do. (Easy case, do people expect to be able to do LET ?y := ?y 
+ 1 with any other effect besides returning no solutions.)

The Chairs do believe that this pretty clearly falls outside the scope 
of our charter, but we're considering it nevertheless given the new 
information.

Lee

> i.e. less verbose than SELECT *, (?x+?y AS ?z) without the pain of 
> needing to get the "*" right; better appearance for usse when there are 
> several assignments.
> 
> What do you think Holger is asking for?
> In what way does it fall outside syntactic sugar?
>    I would find a concrete example we can discuss helpful.
> Do you have a different definition of syntactic sugar?
> 
>     Andy
> 
> 
Received on Tuesday, 10 November 2009 21:46:43 GMT

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