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Question on XQuery formal semantics

From: Axel Polleres <axel.polleres@deri.org>
Date: Wed, 2 Mar 2011 15:22:58 +0000
Message-Id: <90D567C2-2988-47FB-9B5C-B69E14090D45@deri.org>
Cc: Nuno Alexandre Lopes <nuno.lopes@deri.org>, Stefan Bischof <stefan.bischof@deri.org>
To: public-qt-comments@w3.org
(re-send from Jan26, seems this message didn't get through)

Dear XQuery WG,

Although we don't think the XQuery formal semantics document [1] is currently open for comments within the working group, we would appreciate a small clarification (or pointers to earlier discussions in this regard) on the "function" fs:new:

First of all, fs:new appears in the document several times, before it is actually explained (in acouple of normalization rule).

Then, the first time it is explained is within the normalization rule in section 4.12.1. Here it says:

"Note that the following normalization rule uses a variable $fs:new, which is a newly created variable which must not conflict with any variables already in scope."

We are not entirely clear, what "scope" means here. The term "scope" doesn't seem to be defined in the context of normalization rules, it seems. What's particularly worrying us it, that this does not formally seem to preclude that the newly generated variable is - for instance - a variable which is actually used later on in a return clause.  

We acknowledge that this is probably a pretty theoretical only problem, since, and this is pretty sure what you wanted to say, you mean that fs:new would create a new variable that doesn't appear anywhere else in the query at hand and that any "call" to fs:new during normalisation would create such a new variable, yes? Still, we are afraid this needs a bit of clarification, unless we missed something.

Could you comment on that?

thanks a lot,

Axel, Nuno, Stefan

1. http://www.w3.org/TR/2010/REC-xquery-semantics-20101214/
Received on Wednesday, 2 March 2011 15:24:00 UTC

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