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Possible error in the SPARQL 1.1 spec

From: Bernardo Cuenca Grau <bernardo.cuenca.grau@cs.ox.ac.uk>
Date: Fri, 19 Jun 2015 12:55:58 +0100
Message-ID: <CAH4DSMUs0PW+1-tr5CzFfp0RZwMB1YSG-hr9yapm=C4Kw4=bsA@mail.gmail.com>
To: ivan@w3.org, public-rdf-dawg-comments@w3.org
Dear all,

I would like to report a possible error in the SPARQL 1.1 query language
document, which does not seem to be reflected in the accompanying list of
errata.

The possible error in question is in Section 18.6 (Evaluation Semantics).
If we look at the evaluation of Aggregates

eval(D(G), Aggregation(exprlist, func, scalarvars, P))

We can see that the algebraic function Aggregation takes as last parameter
a pattern P. This seems inconsistent with the semantics of the
corresponding construct in section 18.5 as well as with the transformation
from SPARQL 1.1 into the algebra in Section 18.2.4, which both suggest that
P should be replaced by a group.


There is also some confusion in Section 18.5.1 in the definition of
Aggregation, where on the first line {key_1 -> \Omega_1, \ldots, key_n ->
\Omega_n } is
referred to as a "multiset", whereas the evaluation of groups given before
in the first section produces a "set".


Kind regards,


Prof. Bernardo Cuenca Grau
Associate Professor and Royal Society Research Fellow
Department of Computer Science
University of Oxford.
Received on Friday, 19 June 2015 13:55:22 UTC

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