IRC log of sparql on 2009-07-07

Timestamps are in UTC.

13:59:37 [RRSAgent]

RRSAgent has joined #sparql

13:59:37 [RRSAgent]

logging to http://www.w3.org/2009/07/07-sparql-irc

13:59:39 [trackbot]

RRSAgent, make logs world

13:59:39 [Zakim]

Zakim has joined #sparql

13:59:41 [trackbot]

Zakim, this will be 77277

13:59:41 [Zakim]

ok, trackbot; I see SW_(SPARQL)10:00AM scheduled to start in 1 minute

13:59:42 [trackbot]

Meeting: SPARQL Working Group Teleconference

13:59:42 [trackbot]

Date: 07 July 2009

13:59:51 [LeeF]

zakim, this will be SPARQL

13:59:51 [Zakim]

ok, LeeF, I see SW_(SPARQL)10:00AM already started

13:59:56 [LeeF]

zakim, who's on the phone?

13:59:56 [Zakim]

On the phone I see john-l, kasei (muted)

14:00:05 [LeeF]

zakim, code?

14:00:05 [Zakim]

the conference code is 77277 (tel:+1.617.761.6200 tel:+33.4.89.06.34.99 tel:+44.117.370.6152), LeeF

14:00:28 [Zakim]

+LeeF

14:00:42 [Zakim]

+??P22

14:00:52 [KjetilK]

Zakim, ??P22 is me

14:01:00 [Zakim]

+KjetilK; got it

14:01:04 [Zakim]

+pgearon

14:01:20 [Zakim]

+??P25

14:01:23 [AndyS]

zakim, ??P25 is me

14:01:24 [KjetilK]

Zakim, mute me

14:01:37 [AndyS]

AndyS has joined #sparql

14:01:40 [Zakim]

+AndyS; got it

14:01:42 [Zakim]

KjetilK should now be muted

14:01:43 [AndyS]

AndyS has joined #sparql

14:01:46 [Zakim]

+[IBM]

14:01:56 [ivan]

zakim, dial ivan-voip

14:02:04 [Zakim]

ok, ivan; the call is being made

14:02:06 [Zakim]

+Ivan

14:02:12 [LeeF]

zakim, [IBM] is temporarily SimonKJ

14:02:19 [Zakim]

+SimonKJ; got it

14:02:29 [SimonS]

SimonS has joined #sparql

14:03:01 [LeeF]

zakim, who's on the phone?

14:03:03 [Zakim]

On the phone I see john-l, kasei (muted), LeeF, KjetilK (muted), pgearon, AndyS, SimonKJ, Ivan

14:03:40 [Zakim]

+SimonS

14:04:03 [Zakim]

+??P40

14:04:03 [LukeWM]

LukeWM has joined #sparql

14:04:19 [Zakim]

-??P40

14:04:22 [Prateek]

Prateek has joined #sparql

14:04:40 [LeeF]

Chair: LeeF

14:04:44 [LeeF]

Scribenick: KjetilK

14:05:01 [Zakim]

+??P42

14:05:11 [Zakim]

+cory

14:05:19 [Prateek]

+Prateek

14:05:19 [LukeWM]

+??P42 is Garlik

14:05:22 [LeeF]

zakim, cory is Prateek

14:05:23 [Zakim]

+Prateek; got it

14:06:10 [LukeWM]

Garlik has LukeWM,SteveH

14:06:39 [LukeWM]

zakim,+??P42 is Garlik

14:06:39 [Zakim]

sorry, LukeWM, I do not recognize a party named '+??P42'

14:06:52 [LukeWM]

zakim, who is on the phone?

14:06:52 [Zakim]

On the phone I see john-l, kasei (muted), LeeF, KjetilK (muted), pgearon, AndyS, SimonKJ, Ivan, SimonS, ??P42, Prateek

14:06:55 [john-l]

Zakim, ??P42 is Garlik

14:06:57 [Zakim]

+Garlik; got it

14:07:17 [LukeWM]

zakim, Garlik has LukeWM,SteveH

14:07:22 [LeeF]

topic: admin

14:07:24 [Zakim]

+LukeWM, SteveH; got it

14:07:29 [LeeF]

PROPOSED: Approve minutes at http://www.w3.org/2009/sparql/meeting/2009-06-30

14:07:56 [Zakim]

+EricP

14:08:03 [KjetilK]

LeeF runs through the agenda

14:08:21 [LeeF]

RESOLVED: Approve minutes at http://www.w3.org/2009/sparql/meeting/2009-06-30

14:09:16 [LeeF]

Next meeting: 2009-07-14 @ 15:00 BST / 10:00 EDT, IvanH to scribe

14:09:35 [alepas]

alepas has joined #sparql

14:09:56 [LeeF]

topic: liaisons

14:10:43 [Zakim]

+??P50

14:10:54 [AlexPassant]

Zakim, ??P50 is me

14:10:54 [Zakim]

+AlexPassant; got it

14:11:01 [LeeF]

topic: open actions

14:11:02 [LeeF]

http://www.w3.org/2009/sparql/track/actions/open

14:11:14 [KjetilK]

LeeF: nothing from the liasons

14:11:32 [LeeF]

trackbot, close ACTION-28

14:11:32 [trackbot]

ACTION-28 Provide tabulator update use case on wiki closed

14:11:48 [LeeF]

trackbot, close ACTION-32

14:11:48 [trackbot]

ACTION-32 Work with SimonS on explaining and comparing UNSAID and MINUS closed

14:11:57 [LeeF]

trackbot, close ACTION-39

14:11:57 [trackbot]

ACTION-39 Review F&R document closed

14:12:03 [LeeF]

Regrets: Axel, Chimezie

14:12:28 [KjetilK]

Zakim, unmute me

14:12:28 [Zakim]

KjetilK should no longer be muted

14:13:00 [LeeF]

trackbot, close ACTION-45

14:13:00 [trackbot]

ACTION-45 Adopt one more additional syntaxe UNSAID or NOT EXISTS for negation closed

14:13:04 [KjetilK]

thanks...

14:13:14 [LeeF]

trackbot, close ACTION-46

14:13:14 [trackbot]

ACTION-46 Review F&R closed

14:13:22 [LeeF]

trackbot, close ACTION-50

14:13:22 [trackbot]

ACTION-50 Work with Lee to publish FPWD of features & rationales closed

14:13:51 [LeeF]

topic: Negation

14:14:12 [LeeF]

http://www.w3.org/2009/sparql/wiki/Design:Negation

14:14:55 [KjetilK]

Zakim, who is talking?

14:15:06 [Zakim]

KjetilK, listening for 10 seconds I could not identify any sounds

14:15:28 [KjetilK]

ericP: I can say something about the UNSAID and NOT EXISTS

14:15:42 [AndyS]

q+ to disagree with that framing :-)

14:16:01 [KjetilK]

s/NOT EXISTS/MINUS/

14:16:22 [pgearon]

+1 for finding MINUS easier to figure out

14:17:06 [ivan]

q+

14:17:12 [LeeF]

ack AndyS

14:17:12 [Zakim]

AndyS, you wanted to disagree with that framing :-)

14:17:32 [KjetilK]

LeeF: for the simple cases "find the people who doesn't have a homepage", are those the same?

14:17:37 [KjetilK]

ericP: yeah

14:18:27 [LeeF]

ack ivan

14:18:45 [LeeF]

NOT EXISTS == UNSAID

14:20:01 [LeeF]

EricP's mail comparing MINUS & UNSAID is http://lists.w3.org/Archives/Public/public-rdf-dawg/2009JulSep/0022.html

14:21:00 [KjetilK]

AndyS: can you have a look at the negation design page and say where it starts to get confusing?

14:21:43 [KjetilK]

LeeF: I think that <NOT%20EXISTS> owl:sameAs <UNSAID>

14:22:05 [KjetilK]

...for the purpose of this discussion

14:22:13 [pgearon]

+q on syntactic use of MINUS

14:22:24 [KjetilK]

AndyS: NOT EXISTS is always a filter

14:24:14 [LeeF]

A. B. NOT EXISTS { C } . D. means Join(A . B) _then_ Filter out solutions compatible with Eval(C) _then_ join with D ?

14:25:06 [KjetilK]

ack pgearon

14:25:06 [Zakim]

pgearon, you wanted to comment on syntactic use of MINUS

14:25:09 [LeeF]

q+ to ask for more help understanding the difference :)

14:26:16 [AndyS]

q+ to ask if there is a difference without OPTIONAL?

14:27:10 [KjetilK]

LeeF: I think we need a deeper understanding of NOT EXISTS vs MINUS

14:27:12 [AndyS]

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14:27:34 [AndyS]

kasei?

14:27:51 [kasei]

yes?

14:28:09 [LeeF]

matches == same variables bound to same values

14:28:23 [AndyS]

You have UNSAID - does your experience help here to explain things?

14:28:59 [kasei]

mine is implemented essentially as you've described yours, equivalent to a filter.

14:29:39 [kasei]

with variable substitution from the result in the expr/bgp and then testing for existence.

14:30:03 [AndyS]

Example: ?a = "a" MINUS ?b = "b" is ????

14:30:28 [LeeF]

q?

14:30:31 [LeeF]

ack LeeF

14:30:31 [Zakim]

LeeF, you wanted to ask for more help understanding the difference :)

14:30:38 [kasei]

I would assume that would result in { a="a" }

14:30:47 [pgearon]

same here

14:30:53 [AndyS]

SPARQL-Join is ("a", "b")

14:31:05 [LeeF]

A - {?a = "a"} MINUS B - {?a = "a"}

14:31:21 [LeeF]

=> no solutions

14:31:30 [LeeF]

A - {?a = "a", ?b = "b"} MINUS B - {?a = "a"}

14:31:46 [LeeF]

=> no solutions

14:31:48 [ivan]

?

14:32:12 [ivan]

why not ?b="b"

14:32:24 [SteveH]

because you lose the whole solution

14:33:09 [LeeF]

A - {?a = "a", ?b = "b"} MINUS B - {?a = "a", ?c = "c"}

14:33:09 [ivan]

aha, too

14:33:23 [pgearon]

we're using the same "compatibility" test that a "join" uses

14:33:30 [LeeF]

=> no solutions

14:33:43 [ericP]

http://www.w3.org/2009/sparql/wiki/Design:Negation#MINUS_with_unification_on_multiple_columns

14:33:50 [LeeF]

A - {?b = "b"} MINUS B - {?c = "c"}

14:34:21 [LeeF]

joining would give {?b = "b", ?c = "c"}

14:34:21 [bglimm]

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14:34:28 [SteveH]

no, I dont think so

14:34:33 [Zakim]

+bcuencagrau

14:34:55 [bglimm]

Zakim, bcuencagrau is bglimm

14:34:55 [Zakim]

+bglimm; got it

14:35:08 [LeeF]

"""

14:35:09 [LeeF]

Definition: Compatible Mappings

14:35:09 [LeeF]

Two solution mappings µ1 and µ2 are compatible if, for every variable v in dom(µ1) and in dom(µ2), µ1(v) = µ2(v).

14:35:11 [LeeF]

"""

14:36:13 [LeeF]

=> A

14:36:14 [pgearon]

{?b = "b"}

14:36:25 [SteveH]

q+

14:36:42 [SteveH]

I think you get { ?b = "b" } { ?c = "c" }

14:36:51 [LeeF]

MINUS - for each solution A on LHS, remove it if there is at least one solution B on the RHS such that A and B are compatible and A and B share at least one variable in common in their domain

14:36:51 [SteveH]

not { ?b = "b", ?c = "c" }

14:37:25 [pgearon]

+q

14:37:28 [SteveH]

q-

14:37:34 [AndyS]

UNION gives { ?b = "b" } { ?c = "c" }

14:38:00 [SimonS]

q+

14:38:37 [AndyS]

AndyS has joined #sparql

14:38:52 [KjetilK]

ack AndyS

14:38:52 [Zakim]

AndyS, you wanted to ask if there is a difference without OPTIONAL?

14:38:55 [LeeF]

ack pgearon

14:38:59 [KjetilK]

ack pgearon

14:39:12 [LeeF]

q+ AndyS to ask if there is a difference without OPTIONAL?

14:40:33 [SimonS]

q-

14:40:38 [bglimm]

Zakim, mute me

14:40:38 [Zakim]

bglimm should now be muted

14:41:09 [LeeF]

q?

14:41:22 [LeeF]

ack AndyS

14:41:22 [Zakim]

AndyS, you wanted to ask if there is a difference without OPTIONAL?

14:42:22 [ericP]

q+ to defend that SQL's is the same

14:42:34 [SteveH]

+1 SQL's is the same

14:42:40 [LeeF]

AndyS: there are 3 possible MINUS definitions

14:42:42 [LeeF]

1) SQL's

14:42:45 [LeeF]

2) antijoin

14:42:54 [LeeF]

3) antijoin + restriction on sharing a variable (what LeeF wrote above)

14:43:14 [pgearon]

so it becomes a "set difference" operation in SQL

14:43:48 [kasei]

+1 on "anti-optional" -- underneath, that's exactly how mine is implemented :)

14:44:31 [pgearon]

I've mentioned this before, but I have a blog description of this "antijoin" http://gearon.blogspot.com/2004/10/owlsameas-majority-of-today-was-spent.html

14:44:58 [pgearon]

It's not necessarily well written, but I still think it's correct

14:45:27 [SteveH]

sql example: http://www.1keydata.com/sql/sql-minus.html

14:46:10 [AndyS]

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14:46:39 [ericP]

q-

14:47:01 [AndyS]

Steve - they are column compatible!

14:47:54 [pgearon]

+1 about either approach working for me

14:48:40 [LeeF]

AndyS: the one i find difficult is the pure antijoin where no variables in common means remove the solution

14:48:44 [SimonS]

+1 that restriction on sharing a variable will get us into trouble

14:50:20 [KjetilK]

AndyS: there is a problem of cardinality, if you have 3 on the LHS and 2 on the RHS, do you get 1 or 0?

14:50:28 [LeeF]

kasei, do you have an opinion on this in general?

14:50:29 [KjetilK]

ericP: I'd do what SQL does?

14:51:02 [kasei]

I think you've gotten it right. I prefer unsaid (but not exists is, I believe, just syntactically different).

14:51:21 [kasei]

... and am confused/worried by the 3 different characterizations of minus.

14:51:30 [SteveH]

UNION is horrible

14:52:21 [SimonKJ]

q+

14:52:38 [pgearon]

I think we have a general preference for either of LeeF's (2) or (3)

14:52:41 [LeeF]

ack SimonKJ

14:54:30 [LeeF]

SimonKJ: different approaches have significantly different impacts on query plans / optimizers, even if they'd give the same results

14:55:07 [SteveH]

I would find it had to optimise NOT EXISTS as a FILTER in SQL

14:55:13 [SteveH]

sorry, SPARQL

14:55:22 [pgearon]

+1

14:55:34 [AndyS]

An optimizer can do it how it likes - I do join/leftjoin like that.

14:55:46 [SteveH]

yeah, but I don't

14:55:57 [SteveH]

it would be a lot slower

14:56:28 [AndyS]

??

14:56:58 [pgearon]

I think that we should move it to the mailing list until everyone who wants to discuss it has their head around it

14:57:45 [KjetilK]

LeeF: we go to Update

14:58:14 [KjetilK]

LeeF: AndyS has asked if we could adopt the Member Submission as a starting point

14:58:26 [KjetilK]

AndyS: are there any completely different approaches?

14:58:35 [SteveH]

there's the explicit FILTER() form

14:58:47 [KjetilK]

...if there are, now it is the time to put it on the table

14:58:55 [ivan]

q+

14:59:00 [LeeF]

ack ivan

14:59:01 [SteveH]

what about the diff-like syntax?

14:59:37 [SteveH]

and/or DAV

15:00:02 [KjetilK]

ivan: the Member Submission has a lot of support allready, it is a starting point on its own merits

15:00:03 [pgearon]

I agree with Ivan, SPARQL-Update is already implemented in a lot of places

15:00:47 [Zakim]

-EricP

15:00:50 [Zakim]

-Ivan

15:00:51 [Zakim]

-john-l

15:00:52 [Zakim]

-SimonKJ

15:00:53 [Zakim]

-pgearon

15:00:54 [Zakim]

-Garlik

15:00:56 [Zakim]

-bglimm

15:00:58 [Zakim]

-SimonS

15:01:00 [Zakim]

-Prateek

15:01:02 [Zakim]

-AlexPassant

15:01:04 [Zakim]

-LeeF

15:01:04 [SimonKJ]

SimonKJ has left #sparql

15:01:08 [Zakim]

-KjetilK

15:01:10 [Zakim]

-kasei

15:01:12 [Zakim]

-AndyS

15:01:14 [Zakim]

SW_(SPARQL)10:00AM has ended

15:01:16 [Zakim]

Attendees were john-l, kasei, LeeF, KjetilK, pgearon, AndyS, Ivan, SimonKJ, SimonS, Prateek, LukeWM, SteveH, EricP, AlexPassant, bglimm

15:01:49 [kasei]

back to the wiki for rdf issue, the downside to using the upload feature is that it won't be editable...

15:02:02 [LeeF]

KjetilK, do you want to try doing the minutes steps, or would you like me to?

15:02:26 [KjetilK]

LeeF: I'll try

15:03:03 [LukeWM]

LukeWM has joined #sparql

15:03:21 [KjetilK]

LeeF: do I need to tell RRSAgent to generate the minutes first?

15:03:24 [LeeF]

nope

15:03:28 [KjetilK]

ok

15:04:07 [KjetilK]

uh: UnicodeDecodeError

15:05:21 [KjetilK]

UnicodeDecodeError: 'utf8' codec can't decode byte 0xb5 in position 7630: unexpected code byte

15:05:22 [KjetilK]

args = ('utf8', "13:59:37 <RRSAgent> RRSAgent has joined #sparql\n...ou like me to?\n15:02:26 <KjetilK> LeeF: I'll try\n", 7630, 7631, 'unexpected code byte')

15:06:33 [ChrisW]

ChrisW has joined #sparql

15:06:50 [ChrisW]

ChrisW has left #sparql

15:07:20 [KjetilK]

LeeF: any idea what could cause that?

15:07:52 [ericP]

KjetilK, what irc client are you using?

15:10:21 [KjetilK]

ericP: Konversation, on KDE

15:12:32 [ericP]

is it set up to emit utf8?

15:13:33 [ericP]

it's odd, i don't see any non-ascii around 15:02:26

15:14:31 [KjetilK]

ericP, yeah, it is UTF8 by default

15:14:54 [ericP]

aha,

15:15:06 [KjetilK]

I wrote "værsågod" early in the chat...

15:15:19 [ericP]

2009-07-07T14:35:09Z

15:15:33 [ericP]

trouble maker

15:15:55 [KjetilK]

:-)

15:16:18 [KjetilK]

isn't that encoded correctly?

15:16:45 [ericP]

looks like you have to edit the wiki around "Two solution mappings u1 and u2" (where i used 'u' instead of mu in order to not cause more trouble)

15:16:53 [ericP]

do you have a pointer to the wiki page?

15:16:54 [KjetilK]

aha

15:17:16 [KjetilK]

I don't think I ever got that far, it crashed on copy

15:18:56 [ericP]

i've invited the creator to join us for debugging/reparations

15:19:06 [KjetilK]

ok, cool

15:19:31 [KjetilK]

I've got dinner on the table here, I can join you later, perhaps?

15:19:51 [ericP]

sure

15:21:37 [KjetilK]

ok, bbian

15:21:41 [KjetilK]

err, bbiab

15:21:47 [ericP]

pointer to the mihutes?

15:21:52 [ericP]

sorry, irc log?

15:21:56 [ericP]

(so we can fix it)

15:22:07 [sandro]

sandro has joined #sparql

15:22:47 [sandro]

ericP, the error message sais it's position 7630 in http://www.w3.org/2009/07/07-sparql-irc.txt which isn't in utf-8.

15:23:05 [ericP]

odd, it was pasted in utf-8

15:23:52 [ericP]

009-07-07T14:35:09Z <LeeF> Two solution mappings µ1 and µ2 are compatible if, for every variable v in dom(µ1) and in dom(µ2), µ1(v) = µ2(v).

15:24:56 [AndyS]

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15:25:19 [sandro]

Could just be a bug in my code.

15:25:40 [sandro]

I suggest removing those lines from the RRSagent log, doing the copy, then pasting those lines back into the wiki,.

15:25:49 [ericP]

that works

15:26:51 [sandro]

sorry about the bug.

15:27:12 [sandro]

what kind of pretentious person uses mu on IRC anyway. :-)

15:27:26 [ericP]

np at all. just wondered if we should avoid utf-8

15:28:41 [sandro]

honestly, I'm terrible at keeping straight which strings are encoded and which are not, and it's easy for me to accidently decode twice or something, which is probably the bug.

15:33:57 [AndyS]

AndyS has joined #sparql

15:47:42 [ericP]

sandro, are you at the 'tute?

15:47:46 [ericP]

feel like debugging?

15:48:37 [sandro]

nope and nope :-)

15:49:59 [LeeF]

did sandro just call me pretentious? harrumph

16:07:21 [iv_an_ru]

iv_an_ru has joined #sparql

16:07:51 [KjetilK]

:-)

16:08:42 [KjetilK]

did you finish the generation of the minutes?

16:08:56 [ericP]

nah, i suck

16:08:59 [ericP]

got distracted

16:09:09 [ericP]

on it now