IRC log of rdfn on 2010-06-26

Timestamps are in UTC.

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logging to
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rrsagent, set log public
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Meeting: RDF Next Step Workshop
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16:19:00 [pfps]
Where are my tomatoes?
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#rdfn tag for twitter, etc. ?
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scribenick pfps
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what do I need to do to be the scribe
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I made a short URL for the agenda:
16:21:45 [pfps]
official agenda URL
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scribenick: pfps
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Scribe: Peter F. Patel-Schneider
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Introduction of all participants
16:29:00 [dajobe]
and search for lost participants
16:29:01 [pfps]
Today will be presentation of many of the submissions
16:29:17 [pfps]
Tomorrow will be breakout sessions
16:29:31 [pfps]
Also today, initial setup of breakout sessions
16:31:07 [pfps]
Presentation from Richard Cyganiak
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cygri: Four Boundary Conditions for RDF Next Steps
16:32:00 [Jeremy]
16:32:41 [pfps]
Above is a version of Richard's slides
16:32:45 [ojirio]
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16:33:20 [pfps]
cygri: I want to set up boundary conditions on what we can do and what we can't do.
16:33:49 [pfps]
Some information from the slides will not be minuted
16:34:10 [sandro]
cygri: #1: Standards are a tool for achieving interoperability
16:34:17 [pfps]
cygri: Boundary Condition 1: Standards are a tool for achieving interoperability.
16:34:35 [pfps]
cygri: Boundary Condition 2: Change can disrupt the network effect.
16:35:52 [pfps]
cygri: Boundary Condition 3: W3C is not good at R&D.
16:37:18 [pfps]
cygri: Boundary Condition 4: Focus on areas where RDF has proven useful.
16:39:08 [pfps]
cygri: What does this mean?
16:39:43 [pfps]
cygri: Optimality can never be achieved.
16:41:14 [pfps]
cygri: W3C can turn existing practice (quasi-standards) into recommendations.
16:42:08 [pfps]
cygri: We can align the stack.
16:42:21 [pfps]
cygri: Currently the stack is rather messy.
16:43:06 [pfps]
cygri: Even within RDF - e.g., containers vs lists
16:43:53 [mdean]
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cygri: A messy stack causes problems for new people.
16:44:54 [pfps]
cygri: There are ways to align the stack, including deprecation, notes,
16:46:03 [kasei]
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16:46:25 [pfps]
cygri: My preferences - put common practice into Rec, explain the messiness
16:47:46 [juansequeda]
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16:48:23 [pfps]
sandro: What are consequences of only looking at where RDF is useful?
16:49:02 [pfps]
jeremy: Remember the forced compatability between RDF and OWL.
16:49:17 [sandro]
sandro: whar are the things that are NOT areas where RDF has proven useful ?
16:49:57 [sandro]
andy: RDF for encoding OWL ontologies vs OWL for defining RDF properties
16:50:35 [pfps]
cygri: Don't come up with a new semantics for RDF here (e.g., to make it work with blogic).
16:50:37 [sandro]
cygri: As a foundation for KR languages, RDF has not proven itself. Let's not spend a lot of time with the RDF Semantics to make that happen.
16:51:07 [sandro]
david: Be careful of tyranny of the majority; don't kill something just because it's not popular (yet)
16:51:19 [pfps]
david: Let's not preclude the future.
16:51:37 [sandro]
david: On the spectrum between Change Nothing and All-Powerful-WG, where are you?
16:51:56 [AndyS]
TBL: (June 2010)
16:51:59 [pfps]
cygri: Any WG should turn practice into REC, anything else can be dangerous.
16:52:04 [sandro]
cygri: Yes change quasi-standards into Recs. Be very careful about scope-creep on WG fixing stuff.
16:52:44 [sandro]
ivan: cygri, be a guard dog at this workshop, please, pointing out if people violate your principals.
16:52:59 [pfps]
Jeremy Carroll: Towards a minor revision of RDF
16:53:24 [pfps]
16:53:49 [pfps]
jeremy: Small Steps Please!
16:54:19 [pfps]
Jeremy: "If it ain't brokce, don't fix it"
16:54:24 [cygri]
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16:54:51 [pfps]
jeremy: No bugs in RDF spec (contrast with HTML).
16:55:13 [ivan]
rrsagent, draft minutes
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I have made the request to generate ivan
16:55:15 [pfps]
jeremy: The parts that aren't being used don't matter.
16:55:55 [pfps]
jeremy: Let's also consider the costs of doing something (HP spent 0.8M on RDF Rec)
16:55:59 [pfps]
david; HERESY!
16:56:38 [pfps]
jeremy: There are also implementation and training costs, ....
16:57:53 [pfps]
jeremy: Semantic Web has yet to really prove itself, too much change at this point can be detrimental.
16:59:42 [pfps]
jeremy: We should instead be linking data, building apps, ....
17:00:49 [pfps]
jeremy: We could make a few small steps, e.g., deprecate containers, but for any thing someone wants it.
17:01:19 [pfps]
cygri: Deprecating something doesn't mean that the feature has to go away, as users can do it themselves.
17:01:21 [sandro]
cygri: Are those folks using these maybe-deprecate features using them in an interoperable way?
17:01:40 [sandro]
jjc: "Not to be used for new vocabularies" WEAKLY DEPRECATE.
17:01:48 [sandro]
17:01:54 [dajobe]
17:02:02 [ivan]
17:02:03 [pfps]
jeremy: Let's use weak deprecation - "Don't use this in future work - new vocabularies"
17:02:07 [sandro]
jjc: "SHOULD not use"
17:02:36 [sandro]
sandro: RDF parses MUST still parse it
17:02:36 [pfps]
ivan: Real deprecation has this pragmatics that the feature *will* go away.
17:02:57 [sandro]
dbooth: Encourage authors of older vocabs to migrate.
17:03:02 [sandro]
jjc: a MAY
17:03:07 [pfps]
17:03:52 [sandro]
li: maybe will improve computaton complexity
17:04:10 [pfps]
jeremy: "I hate it" is a good enough reason to deprecate something :-)
17:04:23 [pfps]
jeremy: If enough hate it, there is something wrong with it
17:04:31 [pfps]
?: What about backwards compatability?
17:05:01 [pfps]
17:05:41 [pfps]
jeremy: weakly deprecated features shouldn't be used by other recs
17:06:02 [dajobe]
we should have a 'weakly deprecate' column on the whiteboard
17:06:20 [sandro]
david: weakdepr puts a stake in the ground in the direction to go.
17:06:39 [iand]
we can use things like the linked data patterns book to help with deprecating things, e.g.
17:07:10 [pfps]
cygri: foaf uses "archaic" for this purpose
17:07:11 [sandro]
cygri: Danbri says "archaic" not "deprecated".
17:07:56 [pfps]
jeremy: OK do to turtle and named graphs, maybe "follow your nose"
17:07:57 [AndyS]
Better, not "deprecation" but "best practices"
17:08:06 [AxelPolleres]
core/deprecating/best practices seem to revolve around the same issue ... discouraging some less used features, 2 questions are: which features are these, how doe we "brand" that?
17:08:13 [pfps]
jeremy: need to do a cost/benefit analysis
17:08:40 [pgearon]
I'd like to note the regular questions on mailing lists about "I've heard that Containers are bad, but I can't find out why"
17:08:49 [pfps]
jeremy: throwing out RDF semantics could be good, but it would be costly
17:08:52 [sandro]
jjc: Maybe throw our RDF Semantics, but DONT THROW OUT THE BATHWATER WITH THE BABY. Lots of good bathwater there.
17:09:05 [AxelPolleres]
paul, good point...
17:09:58 [pfps]
andys: maybe use "best practices" instead of "weak deprecation" - its cheaper
17:10:18 [sandro]
andy: Always point to a good practice instead, next to anything deprecated
17:10:34 [pfps]
axel: want to discourage some stuff, but we need to come up with a tag for that
17:10:51 [sandro]
paul: for things like rdf:value, say what you should do instead
17:11:03 [pfps]
pgearon: if we are going to "wd" we should also say what *to do*
17:11:23 [pfps]
dajobe: RDF syntaxes 2.0
17:11:45 [pfps]
17:12:21 [Jeremy]
Dave is not representing his employer
17:12:36 [pfps]
dajobe: syntaxes - RDF/XML, N-Triples, RDFa, Turtle - first 2 recs last one not
17:12:42 [Anchakor]
what would be the point of throwing out RDF Semantics? is pat hayes participating in this discussion?
17:13:52 [GuusSchreiber]
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17:14:02 [pfps]
dajobe: other syntaxes have less use
17:14:25 [dingl]
17:15:41 [pfps]
dajobe: some minor change is possible in most syntaxes
17:16:55 [pfps]
dajobe: if backwards compatability is not a concern then can remove rdf:ID, property attributes, reification
17:17:25 [pfps]
dajobe: if major change is possible then turtle could add named graphs
17:18:32 [pfps]
dajobe: recommend that new syntaxes cover *entire* RDF model
17:18:47 [pfps]
dajobe: Turtle - make a REC, polish, tidy
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dajobe: JSON - make a version for RDF as a Rec
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17:20:04 [pfps]
dajobe: binary - no need demonstrated yet
17:20:21 [pfps]
dajobe: named graphs not an obvious addition
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17:21:17 [pfps]
iand: what about ATOM
17:21:30 [pfps]
dajobe: not much takeup for ATOM, so not a major need
17:21:44 [Jeremy]
Somone: what about TriG
17:21:46 [pfps]
pmika: what about a data feed?
17:22:13 [pfps]
ivan: submission on gdata from Google
17:22:40 [pfps]
ivan: also interest from Microsoft
17:23:50 [iand]
I am interested in Atom as an encoding for the RDF model, not an RDF expression of the Atom model
17:23:52 [pfps]
cygri: active work in community - so may need to wait before REC
17:24:19 [pfps]
pmika: there is enough work that it would be good to start on REC now
17:24:47 [sandro]
(Microsoft interested in increasing compatibility between RDF and OData)
17:25:22 [sandro]
Dave: DON'T use binary XML for this.
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17:26:12 [pfps]
dajobe: new XML syntaxes - XML is tree, RDF is graph - so there is no good solution - so don't try
17:26:15 [AndyS]
Turtle is not a subset of TriG which is hard to explain.
17:26:36 [LeeF]
TriG is really a serialization of RDF Datasets (c.f. SPARQL spec)
17:26:40 [pfps]
dajobe: Turtle has worked - why? - it doesn't look like XML
17:27:16 [sandro]
dajobe: DO NOT create any new XML Syntaxes for RDF. There's no way to make a really good one.
17:27:42 [LeeF]
Is anyone here (or elsewhere) strongly suggesting a new XML syntax?
17:27:52 [pfps]
iand: XML has order, RDF doesn't, this is another mismatch
17:28:12 [pfps]
dajobe: some parts of RDF capture order
17:28:17 [iand]
s/iand/Li Ding/
17:28:18 [pfps]
17:28:36 [iand]
17:29:08 [sandro]
jjc: I get a lot of defect reports from end users where people expect their RDF/XML to look nice.
17:29:18 [pfps]
dbooth: What I Want in RDF 2.0
17:29:39 [pfps]
17:30:41 [sandro]
dbooth: What helps US (experts) is far less important than what will help new users.
17:30:54 [pfps]
dbooth: REC for some human-friendly syntax
17:31:12 [pfps]
dbooth: REC for rules language based on SPARQL CONSTRUCT
17:31:50 [LeeF]
Disagree strongly with focusing on new RDF users rather than existing RDF users
17:31:55 [sandro]
dbooth: 1. standards a rules language based on sparql construct.
17:32:00 [pfps]
ivan: isn't this just something for RIF core
17:32:20 [pfps]
ivan: RDF friendly syntax for RIF core?
17:32:32 [pfps]
dbooth: yes
17:32:36 [sandro]
sandro: would a presentation syntax for RIF that looked like SPARQL construct solve the problem
17:32:46 [pfps]
mdean: OPTIONAL in SPARQL is a very powerful construct
17:32:50 [sandro]
dbooth: Yes.
17:33:03 [pfps]
dbooth: SPARQL has wide use - so use it
17:33:04 [LeeF]
sandro, I would be very happy if I had a clearly defined way to understand SPARQL in terms of RIF semantics
17:33:20 [pfps]
pmika: how does this relate to RIF?
17:33:24 [pfps]
dbooth: don't know
17:34:04 [sandro]
sandro: Put this on the agenda for tomorrow -- RIF-SPARQL-etc
17:34:08 [LeeF]
pgearon, I guess the answer to my earlier question is "dbooth is" :-)
17:34:08 [pfps]
dbooth: REC for some XML Schema-friendly serialization - maybe TriX - RDF/XML is awful from many points
17:34:17 [pfps]
dbooth: add literals as subjects
17:34:49 [AxelPolleres]
cool, +1 for the breakout on RDF rules based on SPARQL+RIF ... thinking about making a short presentation why it is *not* a no-brainer, but still feasible
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17:35:22 [pfps]
some people want literals as subjects, some don't
17:35:27 [LeeF]
I'm in the "don't care one way or the other" group :-)
17:35:47 [pgearon]
I have been wondering if literals as subjects could be replaced with formal semantics on rdf:value
17:36:13 [pfps]
ivan: this may raise internationalization issues
17:36:35 [dajobe]
literals as subjects are not allowed in rdf triples as per rdf concepts spec.
17:37:15 [pfps]
dbooth: named graphs - obvious to me
17:37:17 [pgearon]
yes, but there are a lot of parts of the rdf concepts spec that are already being ignored
17:38:17 [pfps]
dbooth: bnodes are a pain - do *something* - maybe get rid of them - maybe skolemization
17:38:26 [sandro]
+1 std way to skolemize bnodes
17:38:43 [sandro]
(for the folks who want to skolemize them)
17:38:45 [pfps]
cygri: too late - bnodes as existentials are here!
17:38:50 [pfps]
axel: bnodes are useful
17:39:11 [pfps]
dbooth: *syntax matters*
17:39:21 [AxelPolleres]
bnodes are natural *local* identifiers, noty accessible form ouside a doc ... by definition.
17:39:28 [AxelPolleres]
... that is needed sometimes
17:39:34 [AndyS]
Bnode refs: Needed to have distributed graphs - currently can't do based on stds only
17:39:54 [pfps]
*break for coffee*
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18:05:31 [Jeremy]
scribenick: Jeremy
18:05:39 [Jeremy]
jun is presenter
18:05:44 [Jeremy]
18:05:59 [Jeremy]
Provenance Requirements for the Next Version of RDF
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18:06:12 [Jeremy]
co-authors: Jun Zhao, Christian Bizer, Yolanda Gil, Paolo Missier, and Satya Sahoo
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18:09:44 [ivan]
slidenick: Jeremy
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18:10:43 [iand]
info URIs could be an option for skolemization
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18:11:48 [Jeremy]
Authors are W3C Provenance Group
18:11:51 [LeeF]
scribenick: Jeremy
18:12:23 [pgearon]
iand: based on UUIDs?
18:12:41 [ivan]
-> Jun Zhao's slides
18:12:51 [iand]
pgearon: register a new bnode domain
18:13:17 [iand]
18:14:20 [pgearon]
iand: OK, so it has the same effect as a UUID, only manually generated, and human readable
18:14:29 [Jeremy]
Problems start with sets of RDF statements ...
18:14:55 [Jeremy]
Provenance allows addressing quality issues with linked data
18:15:19 [sandro]
I'm amused to see Dan Connolly's "Oh Yeah?" button adopted in Jun's slides.
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18:15:51 [dbooth]
zakim, who is here?
18:16:15 [Jeremy]
is zakim here at all?
18:16:24 [dbooth]
I guess not
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18:16:34 [Jeremy]
I see RRSAgent
18:16:38 [dbooth]
rrsagent, where am i?
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18:18:33 [dbooth]
i/Jun Zhao/Topic: Provenance
18:20:01 [dbooth]
peter: Jun seems to be using the term "resource" in a generic English sense, rather than the RDF sense.
18:20:28 [Jeremy]
peter: resource has technical meaning in RDF - the use on slides "Requirement 1: Identity" seems different
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18:22:42 [Jeremy]
peter: Requirement 2: new URIs means new URIs related to old URIs
18:22:46 [Jeremy]
jun: yes
18:23:47 [dbooth]
Jun: When should a new URI be minted versus when should existing URI be used? URI evolution
18:23:56 [AxelPolleres]
peter: this is an issue outside RDF
18:24:11 [AxelPolleres]
???: it IS an issue of the *use* of RDF
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18:26:37 [Jeremy]
Best practice is missing about when to use different items from state of the art
18:26:52 [Jeremy]
Some state of art items are not yet standardized
18:27:14 [Jeremy]
Annotations of RDF graphs general requirement not just provenance
18:28:52 [Jeremy]
18:29:11 [Jeremy]
Scott: it is important to say stuff about a named graph.
18:29:50 [Jeremy]
Scott: from linked open data cloud ...
18:30:29 [Jeremy]
Scott: provenance allows you to say where a particular graph came from how it was made etc
18:30:47 [Jeremy]
Scott: also can say stuff about what is in it - annotations
18:30:57 [Jeremy]
Ivan: what's the question
18:31:19 [dbooth]
i/What I Want in RDF 2.0/Topic: David Booth: What I Want in RDF 2.0/
18:32:11 [Jeremy]
Scott: ??? something about saying something about named graphs ....
18:32:38 [sandro]
mscott: do y'all think it's important to be able to talk about what's in a named graph, to characterize it?
18:33:43 [Jeremy]
andy: it seemed to be talking about a set of statements
18:33:48 [sandro]
ivan: Provenance is somewhat independent of RDF -- but this is important to us to know about their requirements w.r.t. 'named graphs'.
18:33:53 [Jeremy]
andy: this may be more general than named graph
18:34:03 [Jeremy]
jun: we do not want to tie to particular technology
18:34:11 [Jeremy]
jun: not in scope for provenance group
18:34:15 [guus]
a poll in the SW group at VU (35 people) put named graph as THE top req in case of an RDF revision, far ahead of anything else
18:34:32 [Jeremy]
dbooth: do we need another category of output: best practices
18:34:52 [sandro]
I want a little buzzer to press when anyone says "Named Graphs". (I hate the ambiguity of the term.)
18:35:02 [Jeremy]
ivan: i think the provenance XG will come back with suggestion of group
18:35:03 [webr3]
sandro: +100
18:36:03 [dbooth]
i/RDF syntaxes 2.0/Topic: Dave Beckett: RDF syntaxes 2.0
18:36:37 [Jeremy]
debMcG: named graphs need to be first class objects
18:36:53 [Jeremy]
debMcG: with this I am happy - goodbye
18:37:22 [dbooth]
i/Jeremy Carroll: Towards a minor revision of RDF/Topic: Jeremy Carroll: Towards a minor revision of RDF
18:37:31 [Jeremy]
speaker: Elisa
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18:38:07 [Jeremy]
18:38:21 [Jeremy]
OMG Ontology PSIG,
18:38:34 [dbooth]
i/cygri: Four Boundary Conditions for RDF Next Steps/Topic: Richard Cyganiak: Four Boundary Conditions for RDF Next Steps
18:39:00 [dbooth]
Topic: Elisa Kendall: OMG Ontology PSIG Position Paper
18:39:11 [Jeremy]
PSIG = Platform Special Interest Group
18:39:21 [Jeremy]
(slide 1)
18:39:29 [sandro]
(Jeremy, I think sometimes people mean graph literals, sometimes they mean graph reification (reasoning about the elements in a graph), sometimes they mean a way to talk about the state of a triplestore, ....)
18:39:56 [Jeremy]
(Sandro, that ambiguity was deliberate)
18:40:35 [mscottm]
Replying to Sandro's question: "do y'all think it's important to be able to talk about what's in a named graph, to characterize it?" YES. Would be nice if the characterization was available from the SPARQL endpoint.
18:41:00 [Jeremy]
(slides 2) Elisa clarifies difference in charter between OMG and W3C
18:41:39 [sandro]
(Well, I find it causes me almost physical pain, each time I hear someone use the term, because I don't actually know which position they are advocating.)
18:42:28 [Jeremy]
(slide 3) we need one or two documents for the basics
18:42:29 [sandro]
mscottm, I was scribe-assisting, writing down your question, not asking it.
18:42:33 [Jeremy]
not seven or eight
18:43:35 [Jeremy]
sandro: let's put tidying up namespaces on board
18:43:45 [Jeremy]
peter: wehy does namespace matter
18:43:58 [Jeremy]
evan: in metamodel you may namespace into ....
18:44:07 [Jeremy]
a package
18:44:18 [AxelPolleres]
rdfs:domain owl:sameAs rdf:domain ... done?
18:44:49 [sandro]
+1 Axel. :-) DL folks might not like that, though. :-)
18:45:17 [Jeremy]
(slide 4)
18:47:17 [Jeremy]
Sandro: Jena and Sesame are not really APIs because not multiple impl
18:47:27 [AxelPolleres]
but then... why not also owl:sameAs owl:sameAs rdf:sameAs ?... admittedly probably that goes too far, but ... where'd be the border... kinda leaning towards disliking my own proposal now
18:47:30 [webr3]
re named graphs: when people say named graphs, often they mean the URI of the resource which contains a serialized RDF description of the current state of that resource. This doesn't 'Name a Graph' because a graph is a distinct set of triples, you can't change a set and if you add or remove anything it becomes a new set (thus a new graph).
18:47:36 [webr3]
re named graphs: what most want is a way to be able to refer to a distinct set of triples and annotate it in order to provide provenance, enable version control, temporal matters and most uses of RDf in message rather information space, but this can't be achieved with any form of named graph.
18:47:37 [Jeremy]
Sandro: DIG only real API
18:47:44 [webr3]
re named graphs: .. especially not with the conflated named graph most think of, nested graphs *does* however provide the means to cover all aforementioned the things we need /end
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18:48:15 [vmom]
axel: every sparql query result will list:: "x rdf:domain y. x rdfs:domain y". it will be tricky to process it query time
18:48:16 [Jeremy]
DaveB: W3C is not very good at API
18:48:39 [Jeremy]
Elisa: OMG issued an RFP: API for KB
18:48:44 [sandro]
elisa: need standard Java/Enterprise interfaces (APIs)
18:48:52 [Jeremy]
s(slide 5)
18:50:07 [pgearon]
AxelPolleres: I don't want rdf:sameAs.... I want to see rdf:equals (same meaning, but with a name that tells newbies what it actually means)
18:51:34 [Jeremy]
Ivan: DOM went wrong because one api for all languages, but then we have too many languages to support
18:51:48 [Jeremy]
DaveB: Java commuinity should do API for Java
18:52:20 [Jeremy]
Ivan: well defined web interface for SPARQL
18:52:20 [DaveB]
I meant to say w3c isn't so good at programming APIs
18:52:29 [DaveB]
web APIs, a *little* better
18:52:33 [AxelPolleres]
vmon: you mean for SPARQL engines that support entailment... anyways, as mentioned, throughinh the URIs together by sameAs is arguable... where should one stop, we peobably don't want to embrace all of rdfs: and owl: within rdf: ... this is all a surface syntax issue, what it seems to me is rather Elisa is arguing for a "surface syntax" where she doesn't have to care for the namespaces, whereas peter says, "so what, it's all IRIs, it could equally be
18:52:33 [AxelPolleres]
a:domain b:range c:sameAs, d:type..." both are right in a sense
18:52:33 [Jeremy]
(sorry for misscribing)
18:52:37 [pgearon]
DaveB: Yes. I've had several people approach me about this (API for Java). e.g. bblfish
18:53:02 [AxelPolleres]
18:53:43 [Jeremy]
squabbling over the defn of "week"
18:53:46 [Jeremy]
18:54:17 [DaveB]
looks like it'll appear at
18:56:26 [Jeremy]
":What do you want?" (David Wood)
18:56:27 [DaveB]
didn't sound to me like the namespace separation were showstoppers for Elisa
18:56:33 [Jeremy]
Elisa: slide 3: named graphs
18:56:43 [DaveB]
"it would be great"
18:56:46 [DaveB]
= nice to have
18:56:47 [Jeremy]
Elisa: namespace untangling
18:57:19 [Jeremy]
Peter Mika: profile docs in RDFa would be potential soln to namespace problem
18:57:28 [iand]
i think many people are using the "named graph" phrase incompatibly here
18:57:31 [Jeremy]
Richard: agree with Peter Mika
18:57:41 [Jeremy]
Richard: jiggling around is not soln
18:57:50 [Jeremy]
Richard: need to hide
18:58:18 [dbooth]
Richard: RDFa profiles are a good example of how to do this
18:58:26 [Jeremy]
Jeremy: however we jiggle around namespaces someone will be unhappy
18:58:30 [DaveB]
18:58:44 [Jeremy]
Elisa: I would be happy with this sort of soln
18:59:08 [Jeremy]
DaveB: we mix data and schema, untanlged namespaces happen
18:59:36 [Jeremy]
Elisa: minimally, in a document update, add commentary about tangled namespace
18:59:52 [Jeremy]
to say to reader "you are not a lunatic to be confused here"
19:00:19 [Jeremy]
DavidW: WG could issue WG note "Known pitfalls"
19:00:22 [sandro]
19:00:40 [DaveB]
here be pits
19:01:01 [Jeremy]
Axel Polleres
19:01:06 [Jeremy]
next up
19:01:21 [dbooth]
Topic: Axel Polleres: RDF and XML: Towards a Unified Query Layer
19:01:37 [Jeremy]
authors are authors of XSPARQL
19:04:28 [Jeremy]
(slide 5, 6) transformation as well as query
19:05:41 [Jeremy]
slide 8: too many variants of RDF/XML rep of single graph
19:06:24 [Jeremy]
(slide 9) structure of SPARQL and XUQERY similar: head + body
19:07:50 [Jeremy]
slide 14: formal semantics combine
19:07:57 [Jeremy]
slide 16: why
19:08:34 [dbooth]
Anyone know URL for Axel's slides?
19:09:03 [Jeremy]
19:09:07 [Jeremy]
no sorry
19:09:17 [Jeremy]
19:11:32 [Jeremy]
Summary: RDF and XML communities need to talk to one another
19:13:40 [Jeremy]
]Jeremy: I wrote paper on canonical RDF/XML a long time ago
19:13:44 [Jeremy]
on hp web site
19:13:50 [Jeremy]
DaveB: so did I
19:13:59 [Jeremy]
DaveB and Jeremy: but no real take up
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19:14:14 [Jeremy]
Peter: XML and RDF are different, very different
19:15:13 [Jeremy]
Axel: in a way this is a scripting language
19:15:13 [mdean]
should add canonical RDF/XML to whiteboard - probably under RDF-Core Maybe Never
19:15:49 [Jeremy]
DavidWood: where is the line in other formats
19:16:55 [AndyS]
Link all "query" into one thing? Seems top down.
19:17:00 [Jeremy]
?: RDFa how do you query, as XML or using SPARQL
19:17:04 [Jeremy]
Axel: as RDF
19:17:51 [Jeremy]
Sandro: there is a wd in RID on mapping XML docs to RIF Frames (which are RDFs)
19:17:57 [Jeremy]
does that address ?
19:18:10 [Jeremy]
Axel: I am afriad that is like saying XSLT is the answer
19:18:39 [Jeremy]
Sandro: I advocate direct mapping canoncial RDB to RDF and then use rules to transform
19:19:19 [Jeremy]
Peter: XSLT is wrong tech for mapping in second phase of Sandro's case
19:19:30 [Jeremy]
Sandro: RIF is declarative
19:19:39 [Jeremy]
(off topic on quality of RIF)
19:21:40 [Jeremy]
Jeremy: suggests globally replace "RDF URI Reference: with "IRI"
19:22:04 [Jeremy]
DavidWood: aren't you just moving around where the implicit knowledge is?
19:22:06 [DaveB]
the rdb2rdf wg seems to have made one doc:
19:22:25 [Jeremy]
Axel: one use case is legacy datasources
19:22:39 [Jeremy]
In this one you need xforms to RDF queried by SPARQL
19:22:53 [Jeremy]
But other use case is going from RDF to something else
19:23:24 [Jeremy]
DavidW: would this be addressed by canonical RDF/XML
19:23:28 [Jeremy]
Jeremy: it is disgusting
19:23:40 [Jeremy]
AndyS: what about JSON
19:24:08 [Jeremy]
Ivan: there was an attempt to write a 2nd Cambridge Communique
19:24:23 [Jeremy]
it was friendly, but (Sandro): there was not a single consensus statement
19:24:35 [Jeremy]
Ivan: there is a social gap
19:24:52 [Jeremy]
Ivan: some XML people feel threatened (economically) by RDF
19:25:40 [Jeremy]
DavidB = david booth
19:25:45 [Jeremy]
DaveB = Dave Beckett
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19:31:28 [Jeremy]
canoniocal RDF/XML
19:31:48 [Jeremy] [PDF]Jeremy J Carroll Signing RDF Graphs - The SemanticWeb-ISWC 2003, 2003 - Springer
19:33:13 [Jeremy]
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20:15:14 [DeborahMcGuinness]
*greetings from sfo - looks like you are at lunch. sorry had to leave early
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20:32:33 [LeeF]
scribenick: LeeF
20:32:50 [LeeF]
topic: Revisiting Blank Nodes in RDF to Avoid the Semantic Mismatch with SPARQL
20:33:01 [LeeF]
Speaker is Alejandro Mallea
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20:33:27 [LeeF]
Alejandro: I'm going to talk about issues with the semantics of blank nodes
20:33:32 [AxelPolleres]
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20:33:33 [LeeF]
ivan: the semantics of what??? ;-)
20:34:21 [LeeF]
Alejandro: in SQL, NULL doesn't count as an item when counting items
20:34:38 [LeeF]
... in SPARQL, a blank node counts as 1
20:34:44 [LeeF]
AndyS: Why is that similar?
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20:35:00 [LeeF]
Alejandro: We have the same information -- we interpreted a blank node as (SQL) NULL
20:35:15 [LeeF]
ivan: I would read a blank node as "John owns something" and expect a count of 1
20:35:27 [LeeF]
Alejandro: But this behavior is not natural to SQL people
20:35:37 [LeeF]
pfps: everyone agrees the behavior of NULL in SQL is wrong - why should we be wrong like them?
20:36:05 [LeeF]
Alejandro: in SQL NULL means we don't know and in SPARQL blank nodes mean we don't know a name
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20:37:12 [LeeF]
Alejandro: graphs get meaning when nodes are related to real objects
20:38:10 [FabGandon]
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20:38:19 [AndyS]
Codd pointed out there are more than one kind of null in SQL. Codd, E.F. (1990). The Relational Model for Database Management (ed 2)
20:38:21 [sandro]
jjc: You're suffering a bit from the Realist Fallacy, as if there is one right Interpretation
20:38:28 [LeeF]
Alejandro: proposed new definition - A representation of an RDF Graph G is the image of G under an interpretation. In a sense, it's a real version of G.
20:38:58 [sandro]
Alejandro: I'm saying *a* real version, not *the" real version
20:39:10 [dbooth]
dbooth suggests that Alejandro take a look at his SemTech paper, which does not talk about bnodes, but talks a lot about interpretations:
20:39:41 [cygri]
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20:39:42 [LeeF]
Alejandro: the set of representations of G is equal to the union of the representations of all ground versions of G
20:40:35 [LeeF]
Alejandro: two different blank nodes can be replaced by the same URI, which is different from what SPARQL does
20:40:45 [sandro]
wood: *laugh* It's really hard to watch this with Jeremy's head going up and down and pfps's head going side to side
20:41:17 [webr3]
Perhaps a bnode doesn't equate to SQL NULL, perhaps a bnode equates to a table where the primary key is across all columns, thus _:b1 is a pointer to the set of values of that node
20:41:26 [AxelPolleres]
alejandro, FILTER a != b is different from a owl:differentFrom b
20:41:49 [LeeF]
Alejandro: blank nodes don't add much meaning - the only difference that we can tell is that blank nodes are non-dereferenceable
20:42:03 [sandro]
Alejandro: In terms of meaning, blank nodes don't add expressive power to the ground datasets. The only relevant difference is they are non-dereferenceable.
20:42:31 [LeeF]
Alejandro: SPARQL considers distinct blank symbols as distinct objects
20:42:35 [AxelPolleres]
... that is != in SPARQL could *very informally* be viewed as "not known to be equal"
20:43:04 [LeeF]
dbooth: doesn't SPARQL consider blank nodes as possibly distinct items?
20:43:07 [sandro]
dbooth: SPARQL treats them as POSSIBLY distinct, it can't assume they are the same.
20:43:25 [LeeF]
Alejandro: No, they're always distinct
20:43:31 [LeeF]
AxelPolleres: != in SPARQL is syntactical, it's not semantic
20:43:42 [sandro]
axel: The problem is != in SPARQL is syntactic, NOT the semantic not-equal.
20:44:56 [LeeF]
Alejandro: if blank nodes are treated as incomplete information, then the data complexity of SPARQL with only BGPs, SELECT, UNION, and FILTER (?X != ?Y) is coNP-hard
20:45:24 [LeeF]
Alejandro: We then looked at how blank nodes are used on practice on the Web
20:46:03 [LeeF]
Alejandro: blank nodes are rarely used -- often used aspointers to collections of data
20:46:13 [LeeF]
Alejandro: they almost always have an in-defree of 1 and an out-degree of 1 or more
20:47:32 [LeeF]
DavidW: how often? did you measure?
20:47:39 [LeeF]
Alejandro: we didn't measure, but it was every time in our sample
20:48:01 [LeeF]
Alejandro: We also looked at the linked data perspective, which discourages the use of blank nodes
20:48:08 [LeeF]
ivan: that's the opinion of some (respectable) people
20:48:12 [AxelPolleres]
in my humble opinion, the view presented by alejandro reflects mostly coneptual disagreements of what "incomplete data" means between how we treat it in the form of bnodes in RDF and the community doing research on incomplete databases (which is where they're coming from), or no? it is valid to raise that there is this disagreement. Plus, he is right that bnodes are mostly used in the [] way rather than really named bnodes would be needed.
20:48:14 [dbooth]
dbooth: The fact that the in-degree is typically 1 suggests that a *standard* way to write n-ary predicates may help address this.
20:48:49 [LeeF]
Alejandro: we propose to redefine the semantics of blank nodes in RDB to align with the semantics in SPARQL
20:49:00 [LeeF]
Alejandro: That is, assume that two blank nodes with different BNIDs are different
20:49:10 [LeeF]
Alejandro: which turns blank nodes into just non-dereferenceable URIs
20:49:15 [LeeF]
Alejandro: further discussion --
20:49:23 [LeeF]
Alejandro: what is the usage role of blank nodes?
20:49:38 [LeeF]
Alejandro: anonymous idnetifiers, unknown information, eliminated altogether, other?
20:50:02 [AxelPolleres]
bnodes are anonymous identifiers
20:50:16 [LeeF]
DavidW: first suggestion is to make a new type of collection in RDF?
20:50:27 [LeeF]
Alejandro: one option, not necessarily our position
20:51:01 [LeeF]
ivan: We already have blank nodes recorded in a similar fashion, so let's move on
20:51:14 [LeeF]
ivan: we'll discuss in breakout groups tomorrow
20:51:29 [LeeF]
DavidW: we have several SPARQL implementors in the room who have had to deal with this issue
20:51:37 [LeeF]
DavidW: I'd like to know what decisions they've made
20:52:02 [mdean]
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20:52:05 [LeeF]
Jeff(?): does this mean unique name assumption for blank nodes?
20:52:27 [LeeF]
Jeff(?): having unique name assumption only for blank nodes but not for ordinary resources
20:52:51 [LeeF]
Alejandro: My opinion is to eliminate blank nodes - as a group, we propose to align semantics as in SPARQL
20:52:56 [LeeF]
Jeff(?): But what does that mean?
20:52:56 [AndyS]
SPARQL defn for bNode treatment:
20:53:01 [LeeF]
Alejandro: Need help form SPARQL people for that
20:53:11 [LeeF]
DavidW: that's why I brought up the SPARQL implementors
20:53:35 [LeeF]
mdean: last year I analyzed the billion triple challenge corpus - there were 12 datasets there and 5 of those datasets had more blank nodes than URIs
20:53:42 [LeeF]
mdean: that seems to be different results then you got
20:54:10 [LeeF]
Alejandro: in the US Census data set, 99% are blank nodes - very similar usage to what I've outlined here
20:54:20 [LeeF]
mdean: I'm finding a lot of other datasets also have extensive use of blank nodes
20:54:27 [LeeF]
ivan: which means eliminating blank nodes completely would be a big problem
20:54:53 [LeeF]
dbooth: a standardized encoding for Nary predicates ... not sure how much interest htere is there, but this seems like what Alejandro is observing
20:55:49 [AxelPolleres]
I see the point... it is about some awkwardness about leanness or not, which makes the behaviour of queries on lean and non-lean graphs different, or no? that is, you can have different results of queries on a lean version of the same graph, which is equivalent.
20:55:53 [LeeF]
PeterMika: ???
20:56:18 [LeeF]
Alejandro: our result was that everything you can do with blank nodes you can do without
20:56:19 [mdean]
2009 Billion Triples Challenge analysis slide 14
20:56:24 [LeeF]
<general murmur of disagreement>
20:56:59 [LeeF]
AndyS: can I tell the difference in SPARQL without using COUNT(...) ? COUNT ends up closing the world no matter what
20:57:23 [LeeF]
Alejandro: with DISTINCT
20:58:00 [LeeF]
topic: Contextualized RDF Importing
20:58:25 [AxelPolleres]
does that summarize Alejandro's point? ... It is awkward to get potentially different answers on queries on (simple) equivalent RDF graphs?
20:58:33 [AxelPolleres]
speaker is Jie Bao
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20:59:05 [LeeF]
JieBao: <gives two examples of LiDing with different roles & affiliations at different organizations
20:59:24 [LeeF]
JieBao: using owl:sameAs leads to confusing/wrong conclusions because context has been lost
21:00:08 [dbooth]
anyone got the URL for the slides?
21:00:23 [LeeF]
JieBao: 2nd example is assumptions - foaf:mbox is an owl:IFP, but what if in an open forum the value of foaf:mbox is "n/a"?
21:00:42 [LeeF]
JieBao: 3rd example is "World" -- which universe is something true in?
21:01:24 [LeeF]
JieBao: context is something related to the meaning of a sentence (provenance, assumptions, world)
21:01:34 [LeeF]
JieBao: we need a way to make context explicit when a triple is published
21:01:49 [LeeF]
JieBao: what about named graphs, C-OWL, N3 quotation, or Contextx in AI?
21:02:29 [LeeF]
JieBao: Named graphs - name is a context. But contexts are more than a name - some triples may be in multiple contextx - one context may be reused
21:02:30 [webr3]
21:02:58 [LeeF]
cygri: but the same triple can be in multiple graphs, what's the problem?
21:03:11 [LeeF]
JieBao: duplicate information increases the risk of inconsistency and many other things
21:03:24 [LeeF]
DavidW: you're saying that you can't draw a clean boundary to deifne the context?
21:03:26 [LeeF]
JieBao: Yes
21:03:33 [LeeF]
jjc: to me, the context information is just things encoded in graphs
21:03:47 [jjc]
turtles all the way down
21:04:56 [LeeF]
JieBao: C-OWL is about mapping that respects contexts
21:05:20 [LeeF]
JieBao: knowledge transfer is controlled, but context is more than mapping
21:05:31 [LeeF]
JieBao: N# -- contexts are more than quotation
21:05:51 [LeeF]
JieBao: we propose to base on named graphs and add two vocabulary terms: rdf:context & rdf:imports
21:06:15 [LeeF]
JieBao: when we publish a set of triples, we can relate a context document to that set of triples
21:06:49 [LeeF]
JieBao: G: rdf:context C - C may give a context definition document
21:07:34 [LeeF]
JieBao: one graph can import another - each graph may have a context
21:07:48 [LeeF]
JieBao: contexts may have an (in)compatibility relationship with one another that controls what happens on import
21:08:16 [iand]
provenance is a broad term that is basically the main use case for named graphs
21:08:46 [LeeF]
pfps: do documents have multiple graphs in them?
21:08:51 [LeeF]
JieBao: possible but not necessary
21:09:00 [ekendall]
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21:09:06 [LeeF]
pfps: if you don't have multiple graphs in one document, then this looks like owl:imports and owl:incompatileWith
21:09:14 [LeeF]
JieBao: no, because even if you import, you're not required to reuse the semantics
21:09:24 [LeeF]
pfps: I don't see the difference
21:09:38 [LeeF]
JieBao: the difference is copy&paste (OWL) vs. citation
21:10:20 [LeeF]
<discussion of example on slide 12>
21:11:12 [LeeF]
DavidW: we'd have the same conflict between RDF and OWL with this that we have today
21:11:22 [LeeF]
JieBao: yes, but the main difference is having the choice of which parts are reused
21:12:39 [LeeF]
dbooth: am I right in understanding that basically what you're doing would be supported by named graphs?
21:12:43 [LeeF]
JieBao: Yes
21:12:57 [LeeF]
ivan: but you have to add on as a separate specification somewhere which adds the semantics on the imports and context properties
21:13:03 [LeeF]
dbooth: so that would be a semantic extension?
21:13:17 [LeeF]
stefan: so this is named graphs + RDF infrastructure for contexts
21:13:21 [LeeF]
jjc: What needs standardizing?
21:13:37 [LeeF]
jjc: when we did the named graphs work we were trying to minimize the scope of it to focus on a minimal piece
21:13:42 [webr3]
can you trust a graph to specify it's own context..
21:13:47 [LeeF]
jjc: after you do the named graph stuff you can optionally do the hairy stuff
21:14:36 [LeeF]
JieBao: maybe standardize named graph stuff today and context stuff maybe later
21:14:55 [LeeF_]
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21:15:04 [LeeF_]
ivan: this touches on - how would all the inferencing rules of RDF SWchema work together with the contents of named graphs
21:15:15 [LeeF_]
scribenick: LeeF_
21:16:08 [LeeF_]
jjc: if we standardize named graphs, then people can go off and do research not under the W3C banner for things like context
21:16:15 [LeeF_]
DavidW: does your context operate over one or more named graphs?
21:16:22 [LeeF_]
JieBao: Yes
21:16:33 [LeeF_]
DavidW: so you can't have a context that operates on part of a named graph
21:16:37 [LeeF_]
JieBao: Correct
21:16:46 [LeeF_]
DavidW: that helps simplify this
21:17:33 [vmom]
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21:17:45 [LeeF]
scribenick: LeeF
21:17:47 [Anchakor]
found this btw:
21:18:15 [LeeF]
topic: RDF(S) needs annotations
21:18:19 [LeeF]
Speaker is AxelPolleres
21:18:20 [dbooth]
Axel's paper: slides:
21:19:05 [LeeF]
AxelPolleres: context, as before
21:19:18 [LeeF]
AxelPolleres: e.g. time, provenance
21:19:35 [LeeF]
AxelPolleres: trust/certainty
21:21:02 [LeeF]
AxelPolleres: needs come from academia, practice, XGs, etc.
21:21:34 [LeeF]
... two issues are (1) representation of annotations and semantics of annotations
21:21:54 [LeeF]
... we claim that RDF needs agreement on representation and semantics
21:22:01 [LeeF]
... we propose something we call annotated RDFS
21:22:49 [LeeF]
... sensor example - need to capture location of a tag in a room, time of the sensor reading, signal strength
21:23:24 [LeeF]
... one way of representing these is with reification
21:23:50 [LeeF]
... problem is no semantics
21:23:57 [LeeF]
... and reification is not popular
21:24:18 [LeeF]
... other possi bilities is N-Quads, TriG, TriX
21:24:25 [LeeF]
iand: what about N-ary predicates?
21:24:29 [LeeF]
AxelPolleres: that's the same as reification
21:25:15 [LeeF]
dbooth: as N-ary predicates, the subject would be an observation
21:25:21 [LeeF]
<lots of yes murmurs>
21:25:59 [LeeF]
jjc: the distinction is that you can decide up front as part of your data model that certain things such as time, location are important - that becomes the safe as all other parts of your data model OR you can say that in general annotations are important for EVERYTHING so things like time & location should be part of the data model
21:26:29 [LeeF]
AxelPolleres: we need semantics of these annotations for RDF(S)
21:26:34 [Alejandro]
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21:27:50 [LeeF]
... we have a generic framework for describing annotation domains and telling how they can coexist with non-annotated RDF data
21:28:17 [LeeF]
... an annotation domain is a lattice with the representation of the annotation (time intervals), an order between the elements, and a top and bottom element
21:28:52 [LeeF]
???: are partial orders enoguh?
21:28:56 [LeeF]
21:29:06 [LeeF]
AxelPolleres: it does need a top and bottom element
21:29:18 [LeeF]
AxelPolleres: we need a t-norm operator (often AND), and a combining operator (OR)
21:30:25 [LeeF]
AndyS: in the sensor case, there are dependent events, so you can't combine probabilities in such a simple way?
21:30:41 [jun]
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21:30:42 [LeeF]
AxelPolleres: if you're combining annotation domains, then we're treating them independently
21:31:04 [LeeF]
AndyS: in that case with probabilities it's a race to the bottom?
21:31:12 [LeeF]
AxelPolleres: this is not probabilities, it's fuzziness
21:32:14 [LeeF]
... several options for integrating with non-annotated triples
21:32:20 [LeeF]
... (1) treat non-annotated triples as top element
21:32:40 [LeeF]
... (2) another approach is that a triple is true at "some" time (a la blank nodes)
21:32:44 [LeeF]
AndyS: ordered blank nodes!
21:33:08 [LeeF]
AxelPolleres: (3) triple is valid until "now" - current time
21:33:33 [LeeF]
... the only upwards compatible option here is (1)
21:33:42 [LeeF]
iand: how do you annotate which clock was used for the timings?
21:34:28 [LeeF]
iand: meta annotations?
21:34:35 [LeeF]
AxelPolleres: Seriously though. :-)
21:34:49 [LeeF]
AndyS: Do you need layers of annotations? Can I put annotations on the annotations?
21:34:54 [LeeF]
AxelPolleres: No. The annotations are separate.
21:35:06 [sandro]
everyone: it's a problem that you can't annotate annotations
21:35:25 [sandro]
axel: No, not really, but I'll get back to that.
21:35:47 [LeeF]
... inference rules use t-norm and OR operators to combine contexts
21:37:52 [LeeF]
cygri: why do this within W3C rather than defining this somewhere else and advertise it?
21:38:02 [LeeF]
AxelPolleres: you need interoperability when you want to talk about temporal (e.g.) information
21:38:23 [LeeF]
cygri: but W3C is for when there are multiple non-interoperable implementations/proposals out there - I don't see that here
21:38:30 [LeeF]
AxelPolleres: people use ad hoc solutions for this right now
21:39:05 [LeeF]
cygri: think about Good Relations - someone has written it down, promoted it to the point of adoption - what's lacking from what you have now is the deployment & promotion
21:39:21 [mdean]
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21:39:23 [LeeF]
AxelPolleres: Yes & no. The temporal stuff is there and implicit. Provenance is there and implicit.
21:40:00 [LeeF]
jjc: you need to point to something losing money because of an interoperability failure -- there's not enough use here for there to be a problem to solve
21:40:07 [LeeF]
mscottm: there's an opportunity cost
21:40:27 [LeeF]
AxelPolleres: there is RDB2RDF work, but no temporal DB to RDF because people can't do it
21:40:35 [LeeF]
jjc: people are doing RDB2RDF in different interoperable ways
21:40:52 [LeeF]
ivan: what does this require on the core level?
21:42:56 [LeeF]
DavidW: Franz with AllegroGraph got to a point where they neede dto do annotations - their solution was to create a quad store where they assign a URI to every single triple - that allows them to cascade annotations
21:43:06 [LeeF]
ivan: rdflib does this also
21:43:27 [LeeF]
ivan: this could be an alternative to the named graph
21:44:25 [LeeF]
jjc: named graphs is more popular than reification because reification is standardized and people have to use it
21:45:19 [webr3]
assigning a uri to every triple is just creating a named graph where the graph contains exactly one triple, nested graphs would cater for this and named graphs use cases and much more
21:45:39 [LeeF]
sandro: "named graph" is a horrible name - "graph metadata" sounds good
21:45:51 [mscottm]
21:45:52 [LeeF]
topic: RDF: Back to Graph
21:46:03 [sandro]
(actually, I said "graph metadata" is the best I know so far, but it's still not great.
21:46:07 [sandro]
21:46:13 [LeeF]
sandro, mscottm -- in Anzo, every graph has an accompanying "metadata graph" for pretty much these purposes
21:46:14 [DaveB]
let's not re-use/abuse 'metadata'
21:46:37 [sandro]
Tell me something better, DaveB
21:46:41 [LeeF]
speaker is Peter F Patel-Schneider
21:47:06 [DaveB]
21:47:13 [dbooth]
Topic: Peter F Patel-Schneider: RDF: Back to the Graph
21:47:15 [dbooth]
Peter's paper: slides:
21:47:21 [Anchakor]
everything is sort of "meta"
21:47:35 [LeeF]
pfps: I'm not proposing anything different than what's already out there in the world
21:47:42 [LeeF]
... RDF has 2 competing purposes
21:47:49 [LeeF]
... it's a data structure language & it's a KR formalism
21:47:58 [LeeF]
... some people like the 1st, some people like the 2nd, some people do neither
21:48:38 [LeeF]
... the problem here is if you're using this stuff as the foundation to build upon
21:49:11 [LeeF]
... if we believe that all syntax is triples and all semantics is based on RDF semantics, then semantic extensions result in paradoxes
21:49:53 [LeeF]
... the claim that RDF is the basis of the Semantic Web is a lie
21:50:01 [LeeF]
... OWL, RIF, SPARQL don't use triples for everything
21:50:31 [LeeF]
... RDFS uses triples, but there are lots of incomplete implementations
21:51:49 [LeeF]
... let's stop saying that it's true if it's not true
21:52:06 [LeeF]
... let's say that Semantic Web semantics is not necessarily an extension of the RDF semantics
21:52:09 [LeeF]
... syntax is not just triples
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21:52:49 [Anchakor]
pfps +1
21:52:51 [LeeF]
... this is how extensions have been done by mathematical philosophers for ages
21:53:10 [scor_]
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21:53:31 [LeeF]
... invent new syntax when you have something new to say
21:54:05 [LeeF]
... if we did this, then:
21:54:12 [LeeF]
... RDFS might have its own syntax
21:54:17 [LeeF]
... OWL would have its own syntax
21:54:23 [LeeF]
... RIF, SPARQL would have their own syntaxes
21:54:27 [LeeF]
... mostly compatible semantics
21:54:35 [LeeF]
... but this is reality (except for RDFS)
21:55:07 [guus]
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21:55:24 [LeeF]
pfps: there is a good rationale to have a common core of the Semantic Web
21:55:27 [LeeF]
... what shoudl this be?
21:55:35 [LeeF]
... it could be RDF if RDF is containing *data*
21:55:43 [LeeF]
... retain things like "say anything about anything" (more or less)
21:55:53 [LeeF]
... IRIs as global names, entities, properties, ...
21:56:17 [LeeF]
... allow higher languages to use RDF for their data and interpret it however they want
21:56:37 [LeeF]
... OWL could strip out annotations in a pre-processing step (e.g. remove facts not true "now")
21:57:00 [LeeF]
... RDF would still support linked data
21:58:20 [LeeF]
... RDF could be either just a data structuring language or it could be used as part of the syntax of a representation language
21:58:31 [LeeF]
... the higher level language could validate / restrict inputs
21:58:39 [LeeF]
... e.g. restrict vocabulary
21:59:33 [LeeF]
... this leads to a freer Semantic Web
21:59:44 [LeeF]
... this doesn't change that much
22:00:19 [LeeF]
... we can extend RDF freely without necessarily affecting things like RDFS or OWL - the higher pieces can use syntactic or semantic extraction methods to handle the extensions
22:00:24 [sandro]
NOW is a time I want Pat here. :-/
22:00:54 [LeeF]
pfps: MIME types, change over period to make this happen
22:01:52 [LeeF]
dbooth: are you suggesting that the semantics should be separated from the RDF? when RDF is given to someone, then they choose what semantics they apply to the RDF?
22:01:59 [LeeF]
pfps: more or less --
22:02:19 [LeeF]
dbooth: if an RDF author writes RDF and sends it to someone else - how should the consumer of the RDF statements know what semantics are intended by the author?
22:02:22 [LeeF]
pfps: MIME type
22:02:29 [LeeF]
cygri: or rdf:type on the document
22:02:37 [LeeF]
pfps: an internal or extenral syntactic data-ish marker
22:03:21 [LeeF]
stefan: if RDF is a data structure language, it still has a semantics - a la a database has semantics - it may not be full FOL semantics, but it has semantics that can be described and expressed using logics
22:03:29 [LeeF]
... the different languages on the stack still need to respect each other
22:03:40 [LeeF]
... maybe what is wrong here is not what is wrong with RDF but what is wrong with OWL
22:04:11 [LeeF]
pfps: the point is that there's nothing wrong with the duality as long as you're low down in the stack - as soon as you get higher (not just OWL), you run into these problems
22:04:24 [LeeF]
stefan: I think people still typically do more database-oriented work
22:04:39 [LeeF]
pfps: there should retain compatibility issues -- i'm saying that the lockstep is too strict
22:05:00 [LeeF]
jjc: the semantics that RDF statements have differs from the RDF Semantics
22:05:35 [LeeF]
jjc: the underlying RDF semantics actually seems to come from SPARQL
22:05:51 [LeeF]
jjc: I agree that this is the current situation -- what do we need to change?
22:06:05 [LeeF]
pfps: I want to deprecate the RDF Semantics document as it applies to RDF(S)
22:06:11 [LeeF]
pfps: precisely so that other things can be added
22:06:27 [LeeF]
jjc: no one is suggesting mapping a named graph extension to triples
22:06:31 [AndyS]
SPARQL treats things as symbols (still partially there under entailment regimes as well). Oops.
22:06:36 [LeeF]
DavidW: we're saying precisely the opposite
22:06:59 [LeeF]
pfps: but you will need a semantics for named graphs, that will have to cover every corner case for ... whatever.
22:07:11 [LeeF]
pfps: as soon as you have named graphs, you need to deal with cycles, multiple documents, etc.
22:07:21 [LeeF]
jjc: perhaps "maybe never" give a semantics to named graphs
22:07:36 [LeeF]
cygri: of all the stuff i've heard today, this is the one that I really wish we could do
22:07:56 [LeeF]
cygri: there's some stuff in RDF Semantics that can't just be deprecated - maybe 3 pages or so
22:08:03 [LeeF]
pfps: agreed, but most of that is in RDF Concepts as well
22:08:38 [LeeF]
cygri: Could we just point to the useful bits in RDF Semantics and let people ignore the rest of it?
22:08:41 [LeeF]
pfps: Possibly
22:08:48 [LeeF]
cygri: most people are ignoring it already
22:09:03 [LeeF]
pfps: What about RDFS? RDFS has at least an operational semantics for its built-in constructors
22:10:01 [LeeF]
pfps: possible world semantics for RDF graphs belongs at a higher level
22:10:17 [LeeF]
pfps: the principles of Semantic Web at an RDF graph level still belongs to RDF (e.g. identifiers)
22:10:36 [LeeF]
dbooth: I think you need to distinguish between the intended semantics when authored and the semantics that an RDF consumer chooses to apply to it - may be differnet
22:10:40 [LeeF]
22:10:51 [LeeF]
dbooth: suppose 2 graphs A & B with different semantics - what happens when you merge them?
22:10:56 [LeeF]
pfps: depends on compatibility issues
22:11:45 [LeeF]
pfps: i think the intended semantics of the author is always mangled by the consumer
22:11:50 [dbooth]
dbooth: Suppose you have graph Ga with semantics Sa, and graph Gb with semantics Sb. And then you merge graphs Ga and Gb. What should be the semantics of the merged graph?
22:12:06 [Anchakor]
there could be an semantics interoperability vocabulary
22:12:08 [dbooth]
dbooth; Presumably the intended semantics should be both Sa and Sb.
22:13:10 [LeeF]
stefan: in my terms, you're proposing finally applying database semantics into RDF - including UNA, CWA, etc.
22:13:16 [LeeF]
pfps: no! just data, not knowledge
22:13:39 [LeeF]
pgearon: how many people have leaned out a graph in reality?
22:13:41 [LeeF]
jjc: I have!
22:13:58 [LeeF]
AxelPolleres: Can you clarify what you said about RDFS?
22:14:25 [LeeF]
pfps: Personally, I don't think RDFS has much place in the universe - BUT I was saying that there are parts of the semantics of RDFS that if you're going to keep RDFS as an RL then you want some of these semantics
22:14:34 [LeeF]
pfps: maybe the right way to do RDFS is completely operational?
22:14:41 [pgearon]
people have made graphs lean? For commercial purposes? Or for theoretic/research purposes?
22:14:53 [LeeF]
pfps: that frees you from concerns but opens up a can of worms because there are so many more degrees of freedoms compared to model theoretic semantics
22:15:06 [LeeF]
sandro: this is appealing but i'm worried about linked data and worried that the key to linked data is being able to merge graphs
22:15:28 [LeeF]
cygri: triples are just edges in a graph, not true statements
22:15:35 [LeeF]
sandro: I think that breaks the Semantic Web as a social construct
22:15:51 [LeeF]
???: several issues that I want to comment on
22:15:53 [sandro]
dbooth: I agree
22:15:55 [Anchakor]
it's not like the data would have no semantics if rdf semantics is deprecated, it's a sort of signal of the openness of the system, allowing anyone, perhaps just in natural language define semantics
22:16:06 [LeeF]
... Semantic Web calls for proposals for NSF - how do we make available data on the Web and create unexpected use of the data?
22:16:23 [LeeF]
... semantics would be assigned by the user side - publisher can recommend semantics but user will take a different interpretation
22:16:59 [LeeF]
... since we're talking about data structures, do we care about IRIs and HTTP or do we not care?
22:17:19 [LeeF]
... if no linked data, then are we back at graph databases that's been looked at in the past by DB community?
22:17:26 [AndyS]
22:17:28 [LeeF]
pfps: No, I think we want to keep IRIs as names at the data level
22:18:25 [LeeF]
pfps: my proposal is to slash out pieces of the semantics document?
22:18:56 [LeeF]
cygri: I don't think saying that W3C is going to deprecate this document would fly
22:19:05 [LeeF]
... could we summarize this? fold this into RDF Concepts?
22:19:12 [LeeF]
jjc: we could move the word "normative" around
22:19:23 [LeeF]
pfps: Yes, and/or any new additions to RDF don't need to show up in this document
22:19:28 [LeeF]
ivan: that is an important statement
22:19:36 [LeeF]
jjc: the typical reader would not notice this
22:19:45 [LeeF]
pfps: one intended consequence would be to trash the RDFS semantics as wlel
22:19:47 [LeeF]
22:20:12 [dbooth]
The important thing in communicating information is that the RDF consumer must have the *ability* to know what the RDF author intended, whether or not he/she chooses to use it. I.e., the RDF author must be able to indicate the intended semantics.
22:20:13 [dbooth]
But the semantic web is all about *merging* data. This means that the mechanism for indicating the semantics must be amenable to graph merging. This works well if predicate URIs in the graph are used to signal the semantics. I don't see how this could work as well if the intended semantics are *separated* from graph, such as being in a MIME type.
22:20:42 [LeeF]
22:20:48 [dbooth]
Topic: Dinner and Logistics
22:20:59 [ivan]
rrsagent, draft minutes
22:20:59 [RRSAgent]
I have made the request to generate ivan
22:21:33 [Anchakor]
it is hard to imagine this without RDFS
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22:50:40 [AxelPolleres]
scribe: AxelPolleres
22:50:43 [DaveB]
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22:51:23 [AxelPolleres]
Fabien's presentaion upcoming...
22:51:35 [cygri]
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22:51:46 [LeeF]
scribenick: AxelPolleres
22:52:27 [AxelPolleres]
Ivan and Sandro arguing about working overnight...
22:52:57 [AxelPolleres]
fabien: a lot said about named graphs already
22:53:18 [dbooth]
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22:53:33 [AxelPolleres]
... "preaching to the converted"
22:53:55 [scor]
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22:54:07 [ivan]
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22:54:09 [AxelPolleres]
... named graphs useful to model context
22:54:16 [guus]
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22:54:19 [dbooth]
i/Fabien's presentaion upcoming/Topic: Fabien Gandon: Name that Graph
22:54:56 [AxelPolleres]
... document != graph
22:55:09 [mscottm]
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22:55:12 [AxelPolleres]
... so, using the doc URI to speak about a graph is bad practice.
22:55:33 [AxelPolleres]
... we heard about C-OWL, con text ,etc.
22:55:47 [AxelPolleres]
... not yet mentioned: nested typed graphs
22:55:57 [AndyS1]
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22:56:37 [AxelPolleres]
... nested graphs also have an equivalent to bnodes.
22:57:10 [Alejandro_]
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22:57:30 [AxelPolleres]
we use nested graphs in RDF, e.g. for tagging
22:57:54 [AxelPolleres]
fabien: ... or for nested context
22:58:18 [AxelPolleres]
sandro: is that an XML syntax extension? compatible with RDF/XML?
22:58:37 [AxelPolleres]
fabien: we had to modify by an additional attribute.
22:58:48 [AxelPolleres]
sandro: so, not a syntax errror
22:58:53 [sandro]
dajobe: It parses as RDF/XML
22:59:23 [AxelPolleres]
fabien: we use that for various applications.
22:59:40 [jjc]
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22:59:51 [AxelPolleres]
axelR: Can you use different applications at the same time?
23:00:16 [jun]
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23:00:37 [AxelPolleres]
fabien: in principle yes, with some limitation
23:01:16 [AxelPolleres]
fabien: I want RDF1.1 not RDF2.0
23:01:30 [AxelPolleres]
... i.e. agree with small steps
23:02:22 [AxelPolleres]
naso: how can you meet all your requirements with a single mechanism?
23:02:46 [AxelPolleres]
fabien: named graphs are an underpinning for all of those
23:03:34 [AxelPolleres]
stefan: i have you down for named graphs and bnodes
23:03:34 [AxelPolleres]
fabien: I don't like bnodes
23:04:00 [AxelPolleres]
topic: andy's presentation “Supporting Change Propagations in RDF”, Andy Seaborne and Ian Davis
23:04:08 [AxelPolleres]
23:04:39 [AxelPolleres]
AndyS: Web not only read-only
23:04:47 [AxelPolleres]
... changes, edits
23:05:14 [dwood]
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23:05:26 [dbooth]
i/Seaborne and Ian/Topic: Andy Seaborne: Supporting Change Propagation in RDF/
23:05:29 [AxelPolleres]
... looking at the web as a single graph doesn't caprute the semantic web
23:05:36 [dbooth]
Andy's paper: slides:
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23:06:59 [AxelPolleres]
AndyS: moving around large graphs on the web is problematic (gives some examples)
23:07:16 [AxelPolleres]
23:08:51 [AxelPolleres]
AndyS: surveys approaches for change propagation (Delta, RDF Difference, SemVersion, ChangeSets, RDFSync)
23:10:00 [AxelPolleres]
... you move around manifest, two graphs (add, remove)
23:10:14 [AxelPolleres]
... how to package those graphs?
23:11:21 [LeeF]
Think it's a good idea to drill into the idea of RDF Datasets more - I think it would be good to consider them explicitly
23:11:34 [AxelPolleres]
AndyS: Named Graphs is different to RDF Datasets
23:12:29 [AxelPolleres]
+1 to LeeF, understanding you say so far they're already part of SPARQL standard, but you say could be useful for other uses on RDF?
23:13:15 [AxelPolleres]
Andy: exmplifying ChangeSets, sparql update
23:13:25 [AxelPolleres]
... TriG
23:14:00 [AxelPolleres]
s/TriG/Graph Bundles(TriG)
23:14:29 [AxelPolleres]
... Syntax for Graph Bundles matters
23:14:44 [dbooth]
Andy's example in n3:
23:14:45 [dbooth]
23:14:46 [AxelPolleres]
Richard: you could have a literal whose value is a graph.
23:14:46 [dbooth]
@prefix : <> .
23:14:46 [dbooth]
@prefix rdf: <> .
23:14:46 [dbooth]
<> a :ChangeSet;
23:14:46 [dbooth]
:addition [
23:14:47 [dbooth]
a rdf:Statement;
23:14:49 [dbooth]
rdf:object "New Title";
23:14:53 [dbooth]
rdf:predicate <>;
23:14:55 [dbooth]
rdf:subject <> ];
23:14:57 [dbooth]
:changeReason "Change of title";
23:14:59 [dbooth]
:createdDate "2006-01-01T00:00:00Z";
23:15:01 [dbooth]
:creatorName "Anne Onymous";
23:15:03 [dbooth]
:removal [
23:15:05 [dbooth]
a rdf:Statement;
23:15:07 [dbooth]
rdf:object "Original Title";
23:15:09 [dbooth]
rdf:predicate <>;
23:15:11 [dbooth]
rdf:subject <> ];
23:15:13 [dbooth]
:subjectOfChange <> .
23:15:15 [dbooth]
23:15:16 [AxelPolleres]
ivan: vocabulary for change might be useful to standardise as well.
23:16:16 [AxelPolleres]
sandro: how to change bnodes?
23:16:53 [AxelPolleres]
AndyS: that's a problem, TriG NQuad-s don't specify scope of bnodes.
23:17:47 [AxelPolleres]
... bnode could be treated as "_:URI"
23:17:52 [sandro]
AndyS: I want BNodes to be just a kind of URIs, so they're table and I can do this, yes.
23:18:22 [AxelPolleres]
sandro: this would be the strongest use case for changing bnodes.
23:19:07 [dbooth]
Ian: In Talis we don't support bnodes because we want to propagate changes.
23:19:15 [sandro]
sandro: because you need at least some stable notion of URI names in order to propagate changes
23:20:10 [sandro]
andy: the label only has meaning if you go back to the original graph
23:20:20 [sandro]
mika: this is related to feed formats (atom)
23:20:24 [sandro]
ivan: Yes
23:20:25 [AxelPolleres]
axel: seems enough to qualify bnodes by their graph name (bnodes are local identifiers)
23:21:14 [AxelPolleres]
there is an issue on how to model bnode (scope) in named graphs
23:21:23 [dbooth]
Topic: James Leigh: RDF Isolation API
23:21:39 [AxelPolleres]
topic: RDF Isolation API, James Leigh
23:21:41 [AxelPolleres]
23:22:18 [dbooth]
James's paper:
23:22:28 [AxelPolleres]
james: this also needs changesets (connection with andy's talk)
23:23:01 [AxelPolleres]
... protocol to change an RDF store and do query operations
23:23:40 [AxelPolleres]
... can also delegate to other services
23:23:47 [dbooth]
s/topic: RDF Isolation API, //
23:24:17 [ivan]
rrsagent, draft minutes
23:24:17 [RRSAgent]
I have made the request to generate ivan
23:24:37 [AxelPolleres]
james gives an example of a virtual service
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23:26:54 [ekw_]
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23:27:32 [AxelPolleres]
axel: this is rather on top of SPARQL update/SPARQL protocol/SPARQL http-protocol, right?
23:28:02 [AxelPolleres]
james: yes, SPARQL 1.1 doesn't allow service creation
23:28:25 [dbooth]
Topic: James Leigh: An Ordered RDF List
23:28:35 [AxelPolleres]
23:28:53 [dbooth]
James's paper:
23:29:18 [AxelPolleres]
James: currently "two forms of RDF" lists
23:29:48 [AxelPolleres]
... my proposal is to make the rfd:first rdf:rest way "syntactic sugar"
23:30:28 [AxelPolleres]
... in favor of a first-class single RDF term way to write lists.
23:31:46 [AxelPolleres]
james: that would have a big impact in SPARQL, needs treatment of lists, results need to return lists (instead of just a bnode)
23:32:59 [AxelPolleres]
david: I see two aspects, the first could be just addressed by "advice to serializers", the second "needs" modification on SPARQL
23:33:13 [jjc]
select ?n ?o
23:33:16 [AxelPolleres]
ivan: ongoing discussion on SWIG list on RDF lists
23:33:16 [jjc]
23:33:33 [jjc]
<s> rdf:rest { ?n } / rdf:first ?o .
23:33:50 [AxelPolleres]
... one issue is that OWL uses lists heavily, tempering with them is dangerous.
23:34:56 [AxelPolleres]
... another way would be to introduce first-class lists, separately.
23:35:38 [AxelPolleres]
sandro: we have lists as first-class entity in RIF, and syntactic "sour" for rdf:first rdf:rest for RDF compatibility
23:36:23 [pgearon]
The term "hijack" was used by Normal Gray. Pat Hayes said this was historically inaccurate, and suggested the word "pre-jacked"
23:36:50 [AxelPolleres]
???: I like a more flexible way that allows ordered, non ordered, etc.
23:37:18 [AxelPolleres]
AxelR: I do like containers more like collections, removing elements, etc. a lot easier.
23:38:04 [jjc]
23:38:17 [AxelPolleres]
thomas: how, in james' proposal can you refer to e.g. the third element of the list?
23:39:05 [AxelPolleres]
james: you need extra stuff to refer to elements
23:39:32 [AxelPolleres]
jie: why we need all that, may bloat the standard
23:40:07 [AxelPolleres]
peter: do we really need lists-lists *and* lisp-lists?
23:40:23 [ekendall]
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23:40:30 [AxelPolleres]
jjc: points to mail
23:41:16 [AxelPolleres]
discussion about malformed lists...
23:41:46 [AxelPolleres]
ivan: more comments? hearing none...
23:41:59 [vmom]
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23:42:11 [AxelPolleres]
stefan: what to note down (on the whiteboard)
23:42:13 [AxelPolleres]
23:42:41 [AxelPolleres]
stefan: notes lists construct on "RDF Core"
23:42:42 [dbooth]
Topic: Ivan Herman: When owl:sameAs isn’t the Same: An Analysis of Identity Links on the Semantic Web
23:42:42 [dbooth]
Ivan's paper: slides:
23:43:43 [AxelPolleres]
ivan: linked data community uses owl:sameAs all over the place... in some examples used wrongly
23:44:19 [AxelPolleres]
... we should probably define a vocabulary for alternatives, SKOS being a good starting point.
23:44:40 [AxelPolleres]
... but they are defined as having domain skos:concept
23:45:14 [AxelPolleres]
... only case not covered by skos properties is if equality depends on the context
23:45:26 [AxelPolleres]
.... as mentioned by jie earlier.
23:46:12 [webr3]
possibly worth noting | 'One of possibly many URIs which identify something.'
23:46:20 [LeeF]
I think they're hijacking the owl:sameAs predicate ;-)
23:47:01 [AxelPolleres]
richard: more useful, e.g. a property for "two documents having the same topic"
23:47:28 [AxelPolleres]
peter: sameAs may be useful for particular applications.
23:47:29 [jun]
Ivan: there are also cases for modelling the context under which two URIs being stated as the same
23:47:41 [AxelPolleres]
... for that application owl:sameAs is fine.
23:48:12 [AxelPolleres]
ivan: people don't realise the consequences of owl:sameAs
23:48:28 [AxelPolleres]
richard: people jsut us it for creating links
23:48:50 [AxelPolleres]
ivan: there is room for differentiatiation
23:49:23 [AxelPolleres]
... for finer-grained connections.
23:49:42 [AxelPolleres]
richard: in practice people use it in a "best effort" manner
23:50:20 [AxelPolleres]
david: not against other predicates, e.g. skos, great, but not convinced that LOD commmunity is using it really incorrectly.
23:51:01 [AxelPolleres]
... but there is a lack of understanding how owl:sameAs should work in distr environment.
23:51:22 [AxelPolleres]
... look at myths in my semtech slides (remark: link?)
23:51:24 [dbooth]
dbooth's SemTech paper on resource identity, which sheds some light on owl:sameAs:
23:51:27 [Alejandro_]
David, can you post a link to those slides?
23:51:53 [mdean]
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23:52:30 [ekw]
A recent OWL paper that created a taxonomy of relations that might support some LOD use cases for sameAs
23:53:58 [sandro]
yes,! let's call it: rdf:notQuiteTheSameAs
23:54:07 [AxelPolleres]
david: in some application things may be the same.
23:54:12 [pgearon]
what about rdfs:seeAlso?
23:54:25 [sandro]
eh, more than seeAlso
23:54:40 [AxelPolleres]
... may be precise enoguh for some applications, but not for all, that's life, and this is fundamental.
23:54:43 [pgearon]
23:55:11 [sandro]
(I just liked dbooth's phrasing as notQuiteTheSameAs :-)
23:55:33 [dwood]
dbooth's SemTech slides are at
23:55:36 [DaveB]
23:55:48 [sandro]
(I'm mildly in favor of something like this.)
23:56:02 [AxelPolleres]
axel: not sure whether adding mroe URIs solves the problem, people will still make mistakes
23:56:21 [dwood]
Also see the paper by Pat Hayes and Harry Halpin that David referenced:
23:56:37 [AxelPolleres]
jjc: people could use skos:concepts, domain/range are not prescriptive
23:56:55 [AxelPolleres]
guus: jeremy, that's right, but it might scare people off.
23:57:06 [AxelPolleres]
guus: I disagree with david.
23:57:22 [AxelPolleres]
... if we put out a graph, we express our interpretation.
23:57:44 [dbooth]
jeremy, I think that is just adding more muddiness
23:58:38 [sandro]
let's just promote skos:closeMatch
23:59:30 [AxelPolleres]
petermika: for LOD people, reusing owl: may not imply buying into owl semantics