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Meeting minutes 15 August 2006

From: Jeen Broekstra <jeen.broekstra@aduna-software.com>
Date: Wed, 16 Aug 2006 13:24:40 +0200
Message-ID: <44E30078.7050204@aduna-software.com>
To: dawg mailing list <public-rdf-dawg@w3.org>, Kendall Clark <kendall@monkeyfist.com>

---------- http://www.w3.org/2006/08/15-dawg-minutes ----------

  Data Access Working Group Telecon


    15 Aug 2006

See also: IRC log <http://www.w3.org/2006/08/15-dawg-irc>


    Attendees

Present
    KendallClark, ericP, PatH, AndyS, FredZ, Jeen, Bijan, EliasT, LeeF,
    SimonR
Regrets
    LibbyM
Chair
    KendallClark
Scribe
    Jeen


    Contents

    * Topics <#agenda>
         1. 1. Convene [1]RDF Data Access WG meeting of Tuesday, 15
            August, 2006 at 14:30:00 UTC <#item01>
         2. 2. DISTINCT Underspecified <#item02>
         3. 4. Value testing and D-Entailment <#item04>
    * Summary of Action Items <#ActionSummary>

------------------------------------------------------------------------


      1. Convene [1]RDF Data Access WG meeting of Tuesday, 15 August,
      2006 at 14:30:00 UTC

<kendallclark>
http://lists.w3.org/Archives/Public/public-rdf-dawg/2007JulSep/0103.html

andys comments that the agenda is rather long; kendall agrees

<kendallclark> http://www.w3.org/2006/08/08-dawg-minutes

<SimonR> Discussion of correction to minutes:
http://lists.w3.org/Archives/Public/public-rdf-dawg/2006JulSep/0113.html


      3. DISTINCT Underspecified

<kendallclark>
http://lists.w3.org/Archives/Public/public-rdf-dawg/2006JulSep/0092.html

bijan: specification definitely needs tightening

andys: agree

<bijan> ?x ?y

<bijan> _:x :mochi

<bijan> :Bijan :mochi

bijan: andys thinks that this is a possible correct answer for a
distinct query, I do not

<LeeF> bijan, are you saying that you read DISTINCT as NOT-REDUNDANT ?

<LeeF> yes

<LeeF> thanks

<bijan> :bijan :loves :mochi

<bijan> _:x :hates :mochi

<EliasT> :elias :loves :mochi

<kendallclark> I despise it.

<EliasT> :kendallclark :hates :mochi

<kendallclark> a discussion in where?

andys: we had a discussion with enrico about this earlier, and we agreed
that DISTINCT meant term-distinct, not non-redundant

<kendallclark> ah, 'with enrico'

<Zakim> ericP, you wanted to say that I've been modeling everything
based on SPARQL query symbols (no logical entailment necessary)

bijan: think making leanness available is important

ericP: i've been doing all this based purely on symbols, not on entailment

<SimonR> If we choose not to treat bnodes as existentials, are we
basically choosing not to use RDF Semantics...?

<bijan> Yes

<bijan> IMHO

<SimonR> I agree, and I'm rather alarmed by that.

<kendallclark> At the very least, it's a problem that I have to take to
SWCG, I believe.

andys: I don't understand why this is affected by rdf semantics, because
we are talking about a result set here, not a graph

bijan: it depends on how see the relation with entailment, and also
there is a possible issue when looking at CONSTRUCT

bijan volunteers for an action item on this

<Zakim> ericP, you wanted to suggest that bijan has proposed a keyword
that lets andy and bijan agree on at least one form of redundancy

ericP: bijan mentioned "DISTINCT" vs. "LEAN" as two keywords

<SimonR> My take would be this: whatever form of entailment you are
currently using, a solution which is entailed by another solution may be
eliminated from the solution set without loss of information. Only the
order of co-entailed solutions is arbitrary in that case, I think.

<SimonR> Order of elimination, rather.

<bijan> *ACTION:* bijan to show that the "strong" version of DISTNCT
doesn't interfere with intermittent algebraic operations [recorded in
http://www.w3.org/2006/08/15-dawg-minutes.html#action01]

<AndyS> bijan, could you also describe the reduction algorithm as well?
I think I know what it is informally but it would be good to see it
formally. And that can go in the doc.

<bijan> AndyS, yes, that's in the plan

<kendallclark> bijan: let's add another action for that, please

<AndyS> Cool

kendall: the utility of the tool is one consideration, but another
consideration is (PR if you will) respecting RDF semantics

ericP: analogy is an XQuery engine that respects xml:ID

<kendallclark> *ACTION:* Bijan to describe reduction algorithm [recorded
in http://www.w3.org/2006/08/15-dawg-minutes.html#action02]

<Zakim> AndyS, you wanted to talk about the range of use cases (a
difference between AndyS and Bijan)

AndyS: I think that we have a spec that allows writing queries that
respect RDF semantics, but some things are a bit outside that

<SimonR> Treating the bnode identifiers like names rather than
existentials basically would mean they we're choosing a...drat, what the
name for? In logic, where you have a model by interpreting the symbols
back to themselves...it's named about someone.

<SimonR> about/after

bijan: we are chartered in the light of existing specs, so we have to
make _very_ clear that are compliant or, if we deviate, where exactly.

<SimonR> Herbrand model, that's what I was thinking of....

kendall: it's not currently clearly marked where we depart from rdf
semantics, so that is at least a possible and useful thing to do

<bijan> I would work on an appendix detailing the differences

AndyS: I understand and appreciate bijan's concerns with distinct, but
what I would like to see is support from other people on the issue

<kendallclark> Question: Is respecting RDF semantics w/r/t DISTINCT
important to your organization?

SimonR: i think we should base our semantics on rdf, bnodes are
existential variables there and that should be reflected

LeeF: if it turns out that the choice is between RDF semantics or not,
then we should respect. I can see use cases for both ways of distinct
though.

FredZ: I don't know the opinion of my organization
... still forming my own opinion on the issue

ericP: in favor of keeping simple. (symbol based)

jeen: agrees with ericP mostly

<ericP> oh weak, just remembered my other point: i wanted to say that
saddle could express higher level semantics

jeen: needs to form a more thorough opinion on the issue though

EliasT: what Lee said. I also want what is simplest for the user of
SPARQL, which might be seeingonly lean result sets

EliasT:I think simple distinct as ericP defines it, it's fine because
one could post-process to get a lean answer. But I'd rather SPARQL have
LEAN and DISTINCT.

AndyS: I am not so worried about redundant solutions, it doesn't violate
rdf semantics

bijan: there are a number of points where we need alignment. both forms
of distinct are useful. if we are going to sacrifice one of them we need
to be very clear
... i could go either way, as long as we're very clear

<bijan> Well, that's what people disagree :)

<bijan> er

<bijan> on

<SimonR> The particular interpretation's ability to infer extra
statements is directly related to the ability to determine whether
solutions are equal. Similarly to the way we leave it up the engine to
choose to infer extra statements, it's the enginer rather than the query
which can prove that solutions are redundant.


      4. Value testing and D-Entailment

AndyS: i propose "if the graph matching does entailment then distinct
does as well."

<SimonR> What kinds of equalities do we have? In simple entailment, we
have syntactic equality by name. In D-entailment, we might have
additional equalities from the datatype processor. In OWL, we have
explicit statements of equality. Any others?

<kendallclark>
http://lists.w3.org/Archives/Public/public-rdf-dawg/2006JulSep/0095.html

<bijan> There are entailed equalities in OWL

<bijan> And tehre are entailed inequalities wrt the various XSD types in
RDF +D-entailment

bijan: there is some question about how to understand literals with
lexical types that do not correspond to the datatype

ericP: my approach is that we do not expect tools to handle this

bijan: it is underspecified, and there are choices that can be made. I
do not find ericP's apparent choice unreasonable per se. but we need to
explore the options and clarify at least
... also have concerns about some of the options being outside our charter
... (but I don't know for sure if that is the case)

<AndyS> Testcases.

andys: does this discussion apply to all operators?

bijan: yes

<kendallclark> PatH: sounds like a use/mention issue

<kendallclark> (sorry, UPS at the door)

<kendallclark> jeen: i'm trying to take over

<kendallclark> PROPOSED to meet 22 Aug 14:30 UTC, with PatH scribing

APPROVED

<kendallclark> PROPOSED to adjourn

APPROVED

<kendallclark> *ACTION:* *[DONE]* EricP to redraft section 11 to support
extensible datatypes [recorded in
http://www.w3.org/2006/08/08-dawg-minutes.html#action08]

there is some irc bot wizardry involved in publishing the log and
creating the minutes right? can someone help me out?

<kendallclark> *ACTION:* EricP to redraft section 11 to support
extensible datatypes [recorded in
http://www.w3.org/2006/08/08-dawg-minutes.html#action08]

<kendallclark> DONE

<kendallclark> *ACTION:* *[PENDING]* LeeF to To review rq24. [recorded
in http://www.w3.org/2006/08/08-dawg-minutes.html#action04] *[DONE]*

<kendallclark> *ACTION:* *[PENDING]* DanC to review PFPS's comments for
more test cases [recorded in
http://www.w3.org/2006/08/08-dawg-minutes.html#action06] *[PENDING]*
*[CONTINUED]*

<kendallclark> *ACTION:* *[PENDING]* EricP to turn FredZ's test case
sketches into tests. [recorded in
http://www.w3.org/2006/08/08-dawg-minutes.html#action07] *[DONE]*

http://mmm.idiap.ch/mlmi04/MLMI-Talk-016/slides/slide10-0.html

kendall: that link contains something which looks relevant to publishing
minutes

<kendallclark> ah, thanks


    Summary of Action Items

*[NEW]* *ACTION:* Bijan to describe reduction algorithm [recorded in
http://www.w3.org/2006/08/15-dawg-minutes.html#action02]
*[NEW]* *ACTION:* bijan to show that the "strong" version of DISTNCT
doesn't interfere with intermittent algebraic operations [recorded in
http://www.w3.org/2006/08/15-dawg-minutes.html#action01]
*[NEW]* *ACTION:* EricP to redraft section 11 to support extensible
datatypes [recorded in
http://www.w3.org/2006/08/08-dawg-minutes.html#action08]

*[PENDING]* *ACTION:* DanC to review PFPS's comments for more test cases
[recorded in http://www.w3.org/2006/08/08-dawg-minutes.html#action06]

*[DONE]* *ACTION:* EricP to turn FredZ's test case sketches into tests.
[recorded in http://www.w3.org/2006/08/08-dawg-minutes.html#action07]
*[DONE]* *ACTION:* LeeF to To review rq24. [recorded in
http://www.w3.org/2006/08/08-dawg-minutes.html#action04]

[End of minutes]
------------------------------------------------------------------------
Minutes formatted by David Booth's scribe.perl
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$Date: 2006/08/16 11:04:20 $


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Received on Wednesday, 16 August 2006 11:26:39 GMT

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