IRC log of dawg on 2007-01-30

Timestamps are in UTC.

14:28:01 [RRSAgent]

RRSAgent has joined #dawg

14:28:01 [RRSAgent]

logging to http://www.w3.org/2007/01/30-dawg-irc

14:28:04 [LeeF]

zakim, this will be DAWG

14:28:04 [Zakim]

ok, LeeF; I see SW_DAWG()9:30AM scheduled to start in 2 minutes

14:28:41 [LeeF]

LeeF has changed the topic to: Data Access Working Group weekly telecon -- agenda: http://lists.w3.org/Archives/Public/public-rdf-dawg/2007JanMar/0055.html

14:28:51 [LeeF]

Meeting: RDF DAWG Weekly

14:28:56 [LeeF]

Agenda: http://lists.w3.org/Archives/Public/public-rdf-dawg/2007JanMar/0055.html

14:29:00 [LeeF]

Chair: LeeF

14:29:07 [LeeF]

Scribe: PatH

14:29:16 [LeeF]

Regrets: EliasT, Jeen

14:29:27 [LeeF]

agenda + Convene

14:29:32 [LeeF]

agenda + Review ACTION Items

14:29:36 [sdas2]

sdas2 has joined #dawg

14:29:38 [LeeF]

agenda + Test suite

14:29:44 [LeeF]

agenda + Blank node label scope

14:29:58 [LeeF]

agenda + Extent of BGPs (vis a vis FILTERs)

14:30:07 [LeeF]

agenda + Minimal test suite?

14:30:10 [Zakim]

SW_DAWG()9:30AM has now started

14:30:14 [LeeF]

agenda + rq25 status

14:30:17 [Zakim]

+Simon_Raboczi

14:30:21 [LeeF]

zakim, code?

14:30:21 [Zakim]

the conference code is 7333 (tel:+1.617.761.6200 tel:+33.4.89.06.34.99 tel:+44.117.370.6152), LeeF

14:30:45 [Zakim]

+LeeF

14:31:34 [ericP]

Zakim, please dial ericP-617

14:31:34 [Zakim]

ok, ericP; the call is being made

14:31:35 [Zakim]

+EricP

14:31:39 [Zakim]

+Souri_Das

14:31:49 [LeeF]

zakim, disconnect ericP

14:31:49 [Zakim]

EricP is being disconnected

14:31:50 [Zakim]

-EricP

14:32:01 [ericP]

Zakim, please dial ericP-617

14:32:01 [Zakim]

ok, ericP; the call is being made

14:32:02 [Zakim]

+EricP

14:32:36 [Zakim]

+??P1

14:32:38 [AndyS]

zakim, ??P1 is me

14:32:38 [Zakim]

+AndyS; got it

14:35:35 [Zakim]

+Orri_Erling

14:35:42 [ericP]

iv_an_ru_, meeting time

14:36:07 [LeeF]

Scribe: LeeF

14:36:11 [LeeF]

Jan 16. minutes http://www.w3.org/2007/01/16-dawg-minutes

14:36:30 [SimonR]

(Sorry, it always does that and I have no idea how to turn it off. It's probably a security feature...)

14:36:45 [LeeF]

Approved, AndyS seconding

14:36:53 [LeeF]

Jan 23. minutes http://www.w3.org/2007/01/23-dawg-minutes

14:37:17 [SimonR]

Zakim, who's on the phone?

14:37:17 [Zakim]

On the phone I see Simon_Raboczi, LeeF, EricP (muted), Souri_Das, AndyS, Orri_Erling

14:37:29 [LeeF]

Approved, AndyS seconding

14:38:08 [SimonR]

Meet again next week (Feb 6), SimonR to scribe

14:38:44 [LeeF]

zakim, take up agenda 1

14:38:44 [Zakim]

agendum 1. "Convene" taken up [from LeeF]

14:38:50 [LeeF]

zakim, take up agenda 2

14:38:50 [Zakim]

agendum 2. "Review ACTION Items" taken up [from LeeF]

14:39:04 [SimonR]

LeeF: solicits comments on the agenda (additions, deletions) -- no requests from the group for changes

14:39:12 [LeeF]

ACTION: AndyS to reply to http://lists.w3.org/Archives/Public/public-rdf-dawg/2007JanMar/0041

14:39:13 [LeeF]

mentioning the possibility of banning the same bnode id from appearing in multiple BGPs in a query [DONE]

14:39:27 [LeeF]

ACTION: LeeF to look back through minutes and mailing list to determine if the group has made a past decision on blank node scope [DONE]

14:39:53 [LeeF]

ACTION: AndyS to reply to Bob M noting changes in examples in curent algebra [CONTINUES]

14:40:02 [LeeF]

ACTION: EricP to run the yacker tool over and annotate the existing tests [CONTINUES]

14:40:10 [LeeF]

ACTION: Jeen to mark approved tests as dawg:approved [CONTINUES]

14:40:11 [AndyS]

No progess on my action item.

14:40:20 [LeeF]

ACTION: LeeF to remember that the wee, lost filter tests should be put [CONTINUES]

14:40:30 [LeeF]

zakim, take up agendum 3

14:40:30 [Zakim]

agendum 3. "Test suite" taken up [from LeeF]

14:40:50 [LeeF]

Test sutie status from Jeen: http://lists.w3.org/Archives/Public/public-rdf-dawg/2007JanMar/0050.html

14:40:57 [LeeF]

agendum, take up agendum 4

14:41:03 [LeeF]

zakim, take up agendum 4

14:41:03 [Zakim]

agendum 4. "Blank node label scope" taken up [from LeeF]

14:42:19 [LeeF]

LeeF: <explains blank node label scope issue as per http://lists.w3.org/Archives/Public/public-rdf-dawg/2007JanMar/0055.html>

14:42:34 [LeeF]

AndyS: Sometimes you need to use blank node labels instead of square brackets (e.g. shared objects)

14:43:11 [LeeF]

AndyS: Question is then what is the scope of these labels -- right now you can't refer to one blank node from a different BGP, but you can reuse the label to mean a different bnode

14:43:13 [LeeF]

... this is confusing

14:43:15 [patH]

patH has joined #dawg

14:43:29 [LeeF]

... I'd rather put the burden on the application writer so that it is something that is caught by the parser

14:43:48 [ericP]

Zakim, ack me

14:43:48 [Zakim]

unmuting EricP

14:43:49 [Zakim]

I see no one on the speaker queue

14:44:17 [LeeF]

ericP: I'm content with that restriction;

14:44:31 [SimonR]

If I recall correctly, we prohibit a variable from being reused between parallel OPTIONAL clauses. I'm still of the impression that when the bnode syntax occurs in a query, it's not an existential (as it would be in a graph), but an `undistinguished' variable. So, the prohibition of reusing variable labels would apply to the undisinguished ones as well.

14:44:51 [Zakim]

+PatH

14:45:04 [AndyS]

SimonR : not any more. Can reuse the var - has a natural meaning in the algebra.

14:45:06 [patH]

hi, sorry late

14:45:31 [SimonR]

AndyS: Turns it into some sort of UNION...?

14:45:50 [ericP]

scribe: patH

14:46:00 [AndyS]

Turns it into "try this, if not try that"

14:46:09 [Zakim]

-LeeF

14:46:21 [iv_an_ru_]

iv_an_ru_ has joined #dawg

14:46:31 [Zakim]

+LeeF

14:46:33 [SimonR]

AndyS, so the order of the OPTIONAL clauses makes a difference now?

14:46:57 [AndyS]

SimonR : yes - that is true for SQL left join as well (in the same way)

14:47:06 [LeeF]

Straw poll: What do you think about the proposal to make it illegal to include the same blank node label in multiple BGPs in a single query?

14:47:13 [LeeF]

zakim, who's here?

14:47:13 [Zakim]

On the phone I see Simon_Raboczi, EricP, Souri_Das, AndyS, Orri_Erling, PatH, LeeF

14:47:15 [Zakim]

On IRC I see iv_an_ru_, patH, sdas2, RRSAgent, Zakim, AndyS, SimonR, afs, SteveH, LeeF, ericP

14:47:37 [patH]

simon:like it

14:48:08 [patH]

eric:yep

14:48:14 [patH]

suri:happy

14:48:30 [SimonR]

If two things are different, the syntax checker forces you to label them differently.

14:48:58 [patH]

ori:good

14:49:15 [patH]

pat:as good as itgets

14:49:23 [SimonR]

PatH: Doesn't like it, but supports it as the lesser evil

14:49:38 [patH]

lee:pity about invalidating existing, but good

14:50:18 [LeeF]

PROPOSED: Blank node labels are scoped to the BGP in which they appear; it is an illegal query to include the same blank node label in multiple BGPs in a single query

14:51:24 [patH]

pat:second

14:51:37 [LeeF]

RESOLVED

14:52:12 [LeeF]

ACTION: AndyS to add text clarifying this resolution to rq25

14:52:16 [LeeF]

ACTION -7

14:52:29 [LeeF]

ACTION: AndyS to add test clarifying the prohibition on blank node labels in multiple BGPs to rq25

14:52:41 [LeeF]

zakim, take up agendum 5

14:52:41 [Zakim]

agendum 5. "Extent of BGPs (vis a vis FILTERs)" taken up [from LeeF]

14:52:43 [AndyS]

s/test/text/

14:53:24 [LeeF]

Andy's test cases on blank node label scope: http://lists.w3.org/Archives/Public/public-rdf-dawg/2007JanMar/0056.html

14:53:40 [LeeF]

Andy's test case on the extent of BGPs: http://lists.w3.org/Archives/Public/public-rdf-dawg/2007JanMar/0052.html

14:54:37 [AndyS]

Example: { <x> :p _:a . FILTER(true) . <x> :q _:a }

14:54:39 [patH]

Issue: does a filter break a BGP into two BGPs?

14:55:58 [LeeF]

AndyS: tension between principles of FILTERs applying to group and BGPs being adjacent triple patterns

14:56:39 [LeeF]

AndyS: If we decide that FILTERs do not break-up a BGP then we probably want a slight grammar change

14:57:02 [ericP]

me

14:57:06 [sdas2]

Was there ever a discussion on banishing FILTER to the far right end?

14:57:41 [LeeF]

ericP: I'm imagining a pattern of query writing that highly interleaves triple patterns with the constraints on those patterns, and I'd like to be able to include the same blank node through all of those

14:57:42 [AndyS]

Souri - yes - there has been a little.

14:58:06 [AndyS]

A balance between that and placing close to the thing it restricts.

14:59:39 [ericP]

{ _:who foaf:mbox ?mbox FILTER regexp(?mbox, "^mailto:") _:who foaf:name ?name FILTER LANGMATCHES(?name "EN") }

15:00:50 [LeeF]

patH: Feels strange to have FILTERs break up scoping which is otherwise in line with the curly braces

15:01:26 [AndyS]

c.f. inserting OPTIONAL or even {} which will break the BGP regardless.

15:02:00 [LeeF]

AndyS: the principle for demarkating the edges of a BGP has been adjacency of triples

15:02:33 [LeeF]

other example: { _:a <p> <o> . { ?x ?y ?z } . _:a <p2> <o2> }

15:03:53 [sdas2]

That looks like three BGPs.

15:04:22 [AndyS]

{ _:a <p> <o> . OPTIONAL { ?x ?y ?z } . _:a <p2> <o2> }

15:05:05 [ericP]

{ ?a <p> <o> . ?a <p2> <o2> OPTIONAL { ?x ?y ?z } }

15:05:18 [ericP]

{ ?a <p> <o> OPTIONAL { ?x ?y ?z } . ?a <p2> <o2> }

15:05:53 [LeeF]

ericP: is there a difference between the above two constructs?

15:06:05 [LeeF]

AndyS: In simple entailment, no; but in higher entailments, perhaps.

15:06:22 [ericP]

{ _:a <p> <o> . OPTIONAL { ?x ?y ?z } . _:a <p2> <o2> }

15:06:27 [ericP]

A

15:06:30 [AndyS]

Different again: {OPTIONAL { ?x ?y ?z } . { ?a <p> <o> } ?a <p2> <o2> }

15:06:39 [ericP]

{ ?a <p> <o> . ?a <p2> <o2> OPTIONAL { ?x ?y ?z } }

15:07:33 [LeeF]

patH: If we decided that that *is* one BGP, then that's the way it is and it could/would be sent to a (e.g.) DL engine that way

15:08:37 [LeeF]

<discussion of what's the nice design here>

15:08:43 [AndyS]

UNION, GRAPH, extra {}

15:08:53 [LeeF]

ericP: possibility, say FILTER does not break up BGPs ...

15:10:06 [ericP]

'{' pattern '}'

15:10:57 [LeeF]

AndyS: I would probably change the production rule name

15:11:12 [LeeF]

zakim, who''s here?

15:11:13 [Zakim]

I don't understand your question, LeeF.

15:11:17 [LeeF]

zakim, who's here?

15:11:17 [Zakim]

On the phone I see Simon_Raboczi, EricP, Souri_Das, AndyS, Orri_Erling, PatH, LeeF

15:11:19 [Zakim]

On IRC I see iv_an_ru_, patH, sdas2, RRSAgent, Zakim, AndyS, SimonR, afs, SteveH, LeeF, ericP

15:11:39 [LeeF]

straw poll: What's your feeling on whether a FILTER should break up a BGP?

15:11:57 [LeeF]

patH: does not break up

15:12:45 [LeeF]

Orri: at first no, but concerns over passing parts to reasoning engines

15:13:18 [LeeF]

Orri: slight preference for not breaking it up

15:13:24 [LeeF]

AndyS: slight preference for breaking it up

15:13:34 [LeeF]

Souri: prefer not breaking it up

15:14:11 [LeeF]

Souri: (since we can always push filters to the end (eqiuvalent meaning), then they shouldn't break up a BGP

15:14:32 [patH]

thnks eric. He is always faster then me :(

15:14:34 [patH]

{ _:a <p> <o> . OPTIONAL { ?x ?y ?z } . _:a <p2> <o2> }

15:14:48 [patH]

?how did tht happen? never mind

15:14:59 [LeeF]

ericP: not breaking it up

15:15:45 [LeeF]

SimonR: not break it up

15:16:19 [patH]

good man

15:17:42 [LeeF]

PROPOSED: FILTER clauses do not break up a BasicGraphPattern; a BGP is an adjacent block of triples, possibly with interleaved FILTER clauses

15:18:12 [LeeF]

ericP seconds

15:18:29 [SimonR]

AndyS: abstains

15:18:34 [LeeF]

RESOLVED, AndyS abstaining

15:19:08 [LeeF]

ACTION: AndyS to clarify the extent of BGPs is not broken up by FILTER clauses and to change production rule name in the grammar

15:19:52 [LeeF]

agenda + ericP and existential nature of bnodes

15:20:09 [LeeF]

zakim, take up agendum 8

15:20:09 [Zakim]

agendum 8. "ericP and existential nature of bnodes" taken up [from LeeF]

15:21:09 [LeeF]

ericP: I think in a bag language such as SPARQL that existentials have a cardinality of 0 or 1

15:21:45 [LeeF]

ericP: current rq25 text uses the word "existential" to describe blank nodes

15:23:00 [LeeF]

http://lists.w3.org/Archives/Public/public-rdf-dawg/2006OctDec/att-0175/28-dawg-minutes.html#item04

15:24:08 [AndyS]

Text in http://www.w3.org/2001/sw/DataAccess/rq23/rq25.html#QSynBlankNodes

15:24:31 [AndyS]

"""Blank nodes in query patterns act as existential variables, not as references to specific blank nodes in the data being queried."""

15:25:24 [AndyS]

If it's the text that a problem, what would be better text?

15:25:33 [SimonR]

I'm (still) under the impression that graph patterns *never* contain real existential bnodes in the same way that RDF graphs do. You could never assert that an existential in a graph is the same existential in your query, which we determined wasn't very useful back in November. We use the same syntax that was developed for bnodes in graph patterns, but it means undistinguished variables instead.

15:25:55 [SimonR]

See Definition 4 in http://www.debruijn.net/publications/ppswr-05.pdf

15:27:53 [patH]

Simon, there isnt a real diference between undistinguished varaible and existential when we are limited to simple (or RDF.RDFS) entailment. They are the same.

15:28:05 [patH]

Until you get to the DL case.

15:28:44 [SimonR]

Pat, okay, let me meditate upon that. :)

15:29:07 [LeeF]

AndyS: I think would be tough to map to SQL with a cardinality of 1 because can't have partial DISTINCT projections in SQL

15:29:28 [patH]

Simon, the killer change in DL is that the language has disjunction in it. So the 'binding' can be either-this-or-that.

15:30:12 [SimonR]

Pat, ahhhhh...

15:31:42 [AndyS]

This is the only use of "existential" in rq25.

15:34:33 [SimonR]

Pat, it would be okay to treat existentials and non-distinguished variables until to get to an interpretation with disjunction in (such as DL), in which case it causes problems.

15:34:51 [SimonR]

(Oops, should've been "Pat:" there)

15:34:58 [LeeF]

+2s/Pat,/Pat:

15:41:44 [patH]

much discussion of wording of 4.1.4. Lee thinks essential point is this sets up to fix a possible misunderstanding. Andy thinks nondistinguished better than existential.

15:41:50 [patH]

maybe.

15:41:53 [sdas2]

Aside: Is '?' right in Rule [13] ('WHERE' ? GroupGraphPattern)

15:42:12 [SimonR]

We have two kinds of interpretation functions, the ones that satisfy the RDF graph's model (which interpret the bnodes) and the query solutions (which interpret the query variables, nondistinguished and otherwise).

15:42:21 [LeeF]

Souri, yes, the WHERE keyword is optional

15:43:32 [sdas2]

I see. So, SELECT ?x {?x :name <John>} is ok?

15:43:58 [AndyS]

Souri, yes.

15:44:11 [sdas2]

Thx.

15:44:13 [AndyS]

ASK { ?x :name "John" }

15:44:28 [LeeF]

zakim, take upa gendum 7

15:44:28 [Zakim]

I don't understand 'take upa gendum 7', LeeF

15:44:35 [SimonR]

Accept-language: en-SQL, en-logician, en-webdeveloper

15:44:58 [AndyS]

unsatisfiable!

15:45:31 [patH]

Pat apologises in writing for being a lousy scribe.

15:45:41 [Zakim]

-Orri_Erling

15:45:41 [AndyS]

ADJOURN

15:45:43 [Zakim]

-Souri_Das

15:45:45 [Zakim]

-PatH

15:45:46 [SimonR]

ADJOURNED at 15:45 Z

15:45:46 [Zakim]

-EricP

15:45:53 [Zakim]

-LeeF

15:45:57 [LeeF]

ericP, I"ll get the minutes to you in a few days

15:45:58 [Zakim]

-AndyS

15:46:03 [LeeF]

rrsagent, please generate minutes

15:46:03 [RRSAgent]

I have made the request to generate http://www.w3.org/2007/01/30-dawg-minutes.html LeeF

15:46:07 [Zakim]

-Simon_Raboczi

15:46:09 [LeeF]

rrsagent, make logs world-access

15:46:11 [Zakim]

SW_DAWG()9:30AM has ended

15:46:13 [Zakim]

Attendees were Simon_Raboczi, LeeF, EricP, Souri_Das, AndyS, Orri_Erling, PatH

15:46:22 [AndyS]

zakim, please leave

15:46:22 [Zakim]

Zakim has left #dawg

15:46:36 [AndyS]

rrsagent, please leave

15:46:36 [RRSAgent]

I see 8 open action items saved in http://www.w3.org/2007/01/30-dawg-actions.rdf :

15:46:36 [RRSAgent]

ACTION: AndyS to reply to http://lists.w3.org/Archives/Public/public-rdf-dawg/2007JanMar/0041 [1]

15:46:36 [RRSAgent]

recorded in http://www.w3.org/2007/01/30-dawg-irc#T14-39-12

15:46:36 [RRSAgent]

ACTION: LeeF to look back through minutes and mailing list to determine if the group has made a past decision on blank node scope [DONE] [2]

15:46:36 [RRSAgent]

recorded in http://www.w3.org/2007/01/30-dawg-irc#T14-39-27

15:46:36 [RRSAgent]

ACTION: AndyS to reply to Bob M noting changes in examples in curent algebra [CONTINUES] [3]

15:46:36 [RRSAgent]

recorded in http://www.w3.org/2007/01/30-dawg-irc#T14-39-53

15:46:36 [RRSAgent]

ACTION: EricP to run the yacker tool over and annotate the existing tests [CONTINUES] [4]

15:46:36 [RRSAgent]

recorded in http://www.w3.org/2007/01/30-dawg-irc#T14-40-02

15:46:36 [RRSAgent]

ACTION: Jeen to mark approved tests as dawg:approved [CONTINUES] [5]

15:46:36 [RRSAgent]

recorded in http://www.w3.org/2007/01/30-dawg-irc#T14-40-10

15:46:36 [RRSAgent]

ACTION: LeeF to remember that the wee, lost filter tests should be put [CONTINUES] [6]

15:46:36 [RRSAgent]

recorded in http://www.w3.org/2007/01/30-dawg-irc#T14-40-20

15:46:36 [RRSAgent]

ACTION: AndyS to add test clarifying the prohibition on blank node labels in multiple BGPs to rq25 [8]

15:46:36 [RRSAgent]

recorded in http://www.w3.org/2007/01/30-dawg-irc#T14-52-29

15:46:36 [RRSAgent]

ACTION: AndyS to clarify the extent of BGPs is not broken up by FILTER clauses and to change production rule name in the grammar [9]

15:46:36 [RRSAgent]

recorded in http://www.w3.org/2007/01/30-dawg-irc#T15-19-08

15:46:43 [AndyS]

simon, please stop recording