17:57:44 <RRSAgent> RRSAgent has joined #shapes
17:57:44 <RRSAgent> logging to http://www.w3.org/2015/07/16-shapes-irc
17:57:46 <trackbot> RRSAgent, make logs rdf-data-shapes
17:57:46 <Zakim> Zakim has joined #shapes
17:57:48 <trackbot> Zakim, this will be SHAPES
17:57:48 <Zakim> I do not see a conference matching that name scheduled within the next hour, trackbot
17:57:49 <trackbot> Meeting: RDF Data Shapes Working Group Teleconference
17:57:49 <trackbot> Date: 16 July 2015
17:59:48 <Dimitris> Dimitris has joined #shapes
18:00:32 <Arnaud> present+ Arnaud, ericP, hknublau, kcoyle, simonstey
18:01:24 <Labra> Labra has joined #shapes
18:01:57 <pfps> pfps has joined #shapes
18:02:07 <pfps> present+ pfps
18:02:31 <Arnaud> present+ labra
18:02:50 <Arnaud> present+ TallTed
18:04:27 <aryman> aryman has joined #shapes
18:04:32 <Arnaud> present+ aryman, Dimitris
18:04:45 <ericP> scribenick: ericP
<ericP> chair: Arnaud
<ericP> agenda: https://www.w3.org/2014/data-shapes/wiki/Meetings:Telecon2015.07.16
<ericP> topic: Admin
18:05:20 <Arnaud> PROPOSED: Approve minutes of the 9 July Telecon: http://www.w3.org/2015/07/09-shapes-minutes.html
18:05:57 <Arnaud> RESOLVED: Approve minutes of the 9 July Telecon: http://www.w3.org/2015/07/09-shapes-minutes.html
18:06:00 <pfps> minutes looked OK to me
18:06:21 <hsolbrig> hsolbrig has joined #shapes
18:06:36 <Arnaud> present+ hsolbrig
<ericP> topic: Disposal of raised issues
18:07:41 <ericP> Arnaud: discussing new issues 73-76
18:07:44 <hknublau> q+
18:07:55 <Arnaud> ack hknublau
18:08:49 <ericP> hknublau: is support for large data instances part of the issue?
18:09:04 <ericP> pfps: SPARQL endpoints often restrict the number of results they return
18:09:19 <ericP> ... this is not [intended to be part of] the requirement
18:09:39 <ericP> ... should reword to "This should work if the data graph is very large."
18:10:34 <ericP> ... could explicity that some SPARQL enpoints only return 1K results so any solution which requires 1B results isn't a solution
18:10:51 <ericP> Arnaud: is that specific to implementations on top of SPARQL?
18:10:57 <Dimitris> +q
18:11:01 <ericP> pfps: it's specific to remote data.
18:11:26 <ericP> ... one can always dump the entire dataset, except that for many endpoints, you are "result-limited".
18:11:58 <ericP> ... could restate this caveat as "it is not acceptable to have to dump the entire database."
18:12:06 <aryman> q+
18:12:09 <ericP> Arnaud: that still sounds like a requirement
18:12:16 <Dimitris> q-
18:12:23 <Arnaud> ack aryman
18:12:33 <ericP> pfps: i'm happy to drop this line
18:12:56 <ericP> aryman: we need to keep the functional and the non-functional separate
18:13:20 <ericP> ... you're saying that the presence of BNodes keeps you from making two+ queries
18:13:53 <simonstey> +
18:13:53 <Arnaud> PROPOSED: Open ISSUE-73-76
18:13:58 <simonstey> +1
18:13:59 <Dimitris> +1
18:13:59 <ericP> s/instances part of the issue?/instances part of issue 76?/
18:14:03 <kcoyle> +1
18:14:04 <TallTed> +1
18:14:04 <ericP> +1
18:14:05 <Labra> +1
18:14:07 <hsolbrig> +1
18:14:20 <aryman> +1
18:14:26 <Arnaud> RESOLVED: Open ISSUE-73-76
18:14:35 <pfps> The point of the last sentence of ISSUE-74 was to prevent a methodology of issuing a single SPARQL query that transfers the entire graph or dataset and then works on it locally.  I struck that sentence to permit progress.
18:14:57 <ericP> Arnaud: we now have 35 open issues
18:15:10 <ericP> ... we may have a couple that don't really matter
18:15:26 <ericP> ... we haven't managed to close one issue/call (/week)
18:17:16 <ericP> ... We have some issues that pfps wanted to resolve before FPWD
18:17:17 <aryman> q+
18:17:20 <Arnaud> topic: ISSUE-66
18:17:20 <trackbot> ISSUE-66 -- SHACL spec ill-founded due to non-convergence on data loops -- open
18:17:20 <trackbot> http://www.w3.org/2014/data-shapes/track/issues/66
18:17:28 <ericP> ... we want readers to understand what the WG is up to
18:18:01 <ericP> ... we discussed this issue's title
18:18:46 <ericP> ... the link has an example which pfps says is undecidable
18:19:18 <ericP> pfps: my pref is to say that recursion is illegal
18:19:40 <ericP> hknublau: i sent a link to my latest proposal
18:19:57 <pfps> q+
18:19:57 <simonstey> ref guide: http://w3c.github.io/data-shapes/shacl-ref/
18:20:14 <ericP> ... the ref guide includes my latest SPARQL queries
18:20:49 <ericP> ... this implements aryman's proposal that recursion is only permitted on valueShape
18:21:17 <ericP> Arnaud: the WG isn't in favor of prohibitiung recursion
18:21:32 <Arnaud> ack aryman
18:21:43 <ericP> ... so we need a recursion solution that addresses some minimal needs
18:21:58 <ericP> aryman: this solution has well-defined semantics
18:22:13 <ericP> ... the algorithm:
18:22:20 <ericP> ... .. start with a node/shape
18:22:30 <ericP> ... .. put that pair on a stack
18:22:37 <ericP> ... .. evaluate local constraints
18:22:50 <ericP> ... .. evaluate recursive shapes
18:23:08 <Arnaud> ack pfps
18:23:09 <ericP> ... .. revisiting the same node/shape pair returns true
18:23:22 <ericP> pfps: this isn't shacl
18:23:55 <aryman> q+
18:23:59 <ericP> ... aryman's impl strategy says "when you get back to the same place, say 'yes'"
18:24:10 <ericP> ... that works in this example
18:24:22 <ericP> ... (this doesn't)
18:24:32 <ericP> Arnaud: we had tree ways:
18:24:38 <ericP> ... .. max recursion
18:24:45 <ericP> ... .. true recursion
18:24:50 <ericP> ... .. mixed
18:25:20 <ericP> ... it seemed folks wanted true recursion, but we were interested in the mixed approach
18:25:25 <Arnaud> ack aryman
18:25:48 <ericP> aryman: when you say it doesn't work for SHACL, that presupposes @@1
18:26:17 <ericP> ... if we say that that general shape structure has a defined answer
18:26:36 <ericP> ... if we want to expand this, we can
18:27:00 <ericP> ... iovka's semantics appear to address this, but we'll know more when she returns
18:27:18 <pfps> iovka may have a well-defined semantics for negative recursion, but that's not the end of the story - is this semantics reasonable?  is this semantics implementable?
18:27:18 <ericP> Arnaud: it seems we need to agree on the solution or a way to get to the solution
18:27:50 <ericP> ... some folks say "give me examples"
18:27:59 <ericP> ... pfps says "i want a general solution"
18:28:11 <pfps> q+
18:28:18 <simonstey> allowing recursion only through valueshape removes potential problems that not/disjunction might produce.. so I'm fine with that approach
18:28:25 <pfps> q-
18:29:05 <aryman> q+
18:29:15 <Arnaud> ack aryman
18:29:27 <hsolbrig> @simonstey - where else would it be possible to do recursion?
18:29:47 <ericP> aryman: is it the case that the candidate FPWD will allow unrestricted negation/disjunction of shapes?
18:30:34 <ericP> Arnaud: would prohibiting disjunction and negation address your issue?
18:31:19 <ericP> pfps: you're asking me to throw out something i consider useful to define something i consider useless
18:31:40 <simonstey> @hsolbrig true that..
18:32:06 <hknublau> q+
18:32:11 <Arnaud> ack hknublau
18:32:20 <hsolbrig> q+
18:32:22 <Dimitris> +q
18:32:25 <ericP> hknublau: i think we should try to be pragmatic here
18:32:59 <ericP> ... we can talk about theory and soundness and whatnot, but in the end folks want the language to get work done.
18:33:07 <Arnaud> ack hsolbrig
18:33:08 <pfps> q+
18:33:46 <ericP> hsolbrig: i'm interested in SHACL to reallize UML class/relation semantics as RDF
18:34:18 <ericP> ... UML abounds with recursion, from dog-ears to complex evaluation to make sure that a recursion terminates.
18:34:23 <aryman> q+
18:34:24 <pfps> UML  self-reference does not necessarily translate into SHACL self-reference of shapes
18:35:03 <pfps> q+ to say that UML recursion does not translate into SHACL recursion
18:35:27 <ericP> Arnaud: are you convinced by pfps's assertion that you can work-around these needs?
18:35:57 <ericP> pfps: UML should not translate into SHACL
18:36:28 <ericP> hsolbrig: so do we have an example of how it's done right?
18:36:41 <ericP> pfps: i'll type a general notion in a sec...
18:37:24 <pfps> a UML definition of a "box" B that has a property back to the box translates into a type property to B and then a constraint that says that the value for B's are B's - B is *not* a shape here
18:37:41 <ericP> s/translate into SHACL/translate into SHACL shapes/
18:38:03 <ericP> pfps: UML classes aren't shapes, they're classes
18:39:34 <ericP> q+
18:39:39 <simonstey> @hsolbrig http://stackoverflow.com/questions/14015305/recursion-in-ocl
18:39:41 <Arnaud> ack Dimitris
18:39:49 <pfps> using SHACL shapes for UML classes ends up with *totally* incorrect behaviour - in the example above an isolated shape would be recognized as B
18:40:31 <Arnaud> ack pf`
18:40:32 <pfps> q-
18:40:39 <ericP> Dimitris: pretty much agree with peter. can we hear use cases where the work-arounds don't work?
18:40:42 <Arnaud> ack pfps
18:41:05 <ericP> pfps: i'm saying that's not been working so far
18:41:20 <ericP> Dimitris: sure, in email, but maybe a wiki will help
18:41:45 <Arnaud> ack aryman
18:41:45 <ericP> Arnaud: can we ask folks who are interested in recursion to post some examples into a wiki page?
18:42:03 <ericP> ... they pfps can say how else it could work
18:42:12 <pfps> recursive shapes *do* add extra expressive power - Polentoni is an example - but are there any use cases that need to do this
18:42:45 <ericP> aryman: pfps's point is that if you attach a type arc to a shape, you don't need another way to recognize those shapes
18:42:47 <pfps> the point *for UML* is that UML data *is* done that way -
18:43:14 <pfps> q+
18:43:22 <ericP> ... that works if your data has these type args, but we don't want to require type arcs
18:43:56 <ericP> ... ericP and I have been using the example where the same node is used for different purposes
18:44:37 <pfps> I want to see a worked-out example of this FOAF story
18:44:50 <Dimitris> *with proper scoping and filtering this can be done*
18:44:57 <pfps> agree with Dimitris
18:45:01 <hsolbrig> UML identifies the classifier, but it makes no assertions about instances including a reference to or name of the classifier.
18:45:15 <ericP> ... e.g. a contact database may require certain fields, but all instances of foaf:Person don't require those fields
18:45:43 <pfps> q+
18:45:44 <Arnaud> ack ericP
18:46:30 <hsolbrig> You *could* assert that, in order to be a valid UML instance a type must be present, but that isn't our situation.
18:46:39 <aryman> q+
18:46:45 <pfps> I *protest* - this argument has come up in the past and has be rebutted
18:46:55 <pfps> s/be/been/
18:46:57 <hsolbrig> reference?
18:47:11 <Arnaud> ack pfps
18:48:01 <ericP> ericP: requiring that nodes are annotated with every type arc to capture the purposes they might use for, we are over-constraining the use of these semweb objects
18:49:16 <ericP> pfps: if you say "i need recursive shape recognition to capture UML", it's not UML
18:50:52 <ericP> ted: there are certain things that people need to do and maybe they're "UML" and maybe that's not exactly the right label but it's important that they do what they need to do
18:51:12 <Arnaud> ack aryman
18:51:19 <pfps> when people say "UML" they should be doing UML
18:51:20 <ericP> Arnaud: we shouldn't get hung up on whether this is true UML or not
18:51:36 <ericP> aryman: do you think sh:valueShape is useful?
18:52:01 <ericP> pfps: with out recursion, you can always macro-expand valueShape?
18:52:09 <hknublau> q+
18:52:20 <ericP> aryman: sure, but as an authoring tool, is it useful?
18:52:37 <ericP> pfps: ok if they're treating it as a macro-expansion
18:52:58 <ericP> aryman: it keeps folks from having to repeat themselves
18:53:10 <ericP> ... it's not problematic in certain siutations.
18:53:38 <ericP> ... even if the shapes graph is recursive, it will still terminate unless the data is circular
18:54:05 <ericP> ... so do you think the defn [we proposed] is correct?
18:54:36 <ericP> ... is it acceptable if the spec has well-founded semantics?
18:54:57 <ericP> pfps: iovka's spec is "interesting" [in a pajorative sense]
18:55:20 <ericP> ... as soon as you get to negated recursion, you have to do a lot of work to figure out the situation.
18:55:39 <ericP> ... it's different from anything anyone's done.
18:55:46 <ericP> ... should we go with it?
18:56:02 <ericP> ... someone has to go with a deep investigation before we buy it.
18:56:24 <Arnaud> ack hknublau
18:56:50 <ericP> hknublau: i have the impression that this whole discussion is an academic dance
18:57:19 <pfps> The question is who in the working group Holger is talking about.
18:57:43 <ericP> ... some folks have a specific solution strategy, macro expansion, but would rather throw the requirements under the bus than change the impl strategy
18:58:40 <ericP> Arnaud: we'll doc use cases in the wiki; pfps and Dimitris will show how they can be done without recursion
18:59:07 <Arnaud> topic: ISSUE-62
18:59:07 <trackbot> ISSUE-62 -- Selection or filtering by arbitrary expressions and shapes -- open
18:59:07 <trackbot> http://www.w3.org/2014/data-shapes/track/issues/62
18:59:15 <hknublau> http://w3c.github.io/data-shapes/shacl/index-2015-07-13.html#scopesAndFilters
18:59:25 <hknublau> https://lists.w3.org/Archives/Public/public-data-shapes-wg/2015Jun/0036.html
18:59:46 <ericP> Arnaud: we have a proposal from hknublau.
19:00:02 <ericP> ... we discussed this before.
19:00:42 <ericP> hknublau: the above link (with the image correction) is my current proposal
19:01:20 <ericP> ... this was an attempt to integrate pfps's scoping mechanism
19:01:32 <kcoyle> kcoyle has joined #shapes
19:02:05 <ericP> ... i took pfps's shapeScope or scopeShape and crated filterShape
19:02:43 <ericP> ... this provides a clean mechanism to defined global properties
19:03:12 <ericP> ... e.g. dublin core saying that every utterance of a property must be a string or in some language
19:03:27 <Dimitris> +q
19:03:38 <Arnaud> ack Dimitris
19:03:49 <Dimitris> cannot hear
19:03:51 <Dimitris> will rejoin
19:04:18 <ericP> Dimitris: i agree with holger's approach
19:04:23 <Dimitris> http://www.w3.org/2014/data-shapes/track/issues/49
19:04:26 <ericP> ... concearned with issue 49
19:04:42 <pfps> this looks promising - I'm not sure if it goes quite far enough - I would like to be able select objects of a property, not just subjects
19:04:47 <ericP> ... if we allow SPARQL templates, we have to decide if the filtering will be evaluated when we have a value shape
19:05:00 <ericP> ... if we permit it, i'm not sure how SPARQL templates will work
19:05:01 <aryman> +1 for the proposal to allow more flexible scoping
19:05:18 <pfps> q+
19:05:46 <ericP> Arnaud: none of this is new. it's been on the list before.
19:05:47 <Arnaud> ack pfps
19:05:58 <ericP> pfps: i think this goes in the right direction
19:06:17 <ericP> ... i'd like the ability to select all those nodes that are values from a property.
19:06:48 <hknublau> q+
19:06:49 <aryman> @pfps - could you select values using an inverse property?
19:06:57 <ericP> Arnaud: back to your issue 49 issue, can we close 62 with the proposal and see about 49 pater?
19:07:01 <ericP> Dimitris: sure
19:07:03 <Arnaud> ack hknublau
19:07:19 <ericP> hknublau: i agree that 49 can be handled seperately
19:07:54 <ericP> ... scopes have to be evaluatable either way, so they can be used as a filter
19:08:56 <Arnaud> PROPOSED: Close ISSUE-62 adopting Holger's proposal, drafted in http://w3c.github.io/data-shapes/shacl/index-2015-07-13.html#scopesAndFilters
19:09:07 <hknublau> +1
19:09:09 <simonstey> +1
19:09:11 <aryman> +1
19:09:12 <Dimitris> +1
19:09:16 <kcoyle> +1
19:09:20 <pfps> +0.9, as I would also like property values
19:09:23 <Labra> 0
19:09:27 <ericP> 0
19:09:30 <TallTed> +1
19:09:30 <hsolbrig> 0
19:09:47 <Arnaud> RESOLVED: Close ISSUE-62 adopting Holger's proposal, drafted in http://w3c.github.io/data-shapes/shacl/index-2015-07-13.html#scopesAndFilters
19:10:39 <hknublau> q+
19:10:51 <Arnaud> ack hknublau
19:11:05 <Arnaud> topic: ISSUE-47
19:11:05 <trackbot> issue-47 -- Can SPARQL-based constraints access the shape graph, and how? -- open
19:11:05 <trackbot> http://www.w3.org/2014/data-shapes/track/issues/47
19:11:27 <pfps> q+
19:11:44 <Arnaud> ack pfps
19:12:30 <aryman> q+
19:12:32 <ericP> pfps: having recursion is independent of whether access to the shapes graph is needed when you're performing validation.
19:12:35 <Arnaud> ack aryman
19:12:57 <pfps> I don't see how the *need* for recursion has anything to do with access to the shape graph when doing validation
19:13:34 <ericP> aryman: suppose we have a non-RDF representation, like ShExC or some other non-RDF representation, we'd not even be contemplating providing access to the shapes graph
19:13:43 <hknublau> q+
19:14:08 <Arnaud> ack hknublau
19:14:17 <ericP> ... what is access to the shapes graph required for recursion
19:14:37 <ericP> hknublau: we need it for closed shapes, lists of arguments, templates...
19:14:49 <pfps> I see no *need* for access to the shape graph when validating shapes at all - it is only a particular implementation that requires this access
19:15:00 <ericP> ... when we want to mix SPARQL with javascript, we need a callback to the server
19:15:18 <Dimitris> +q
19:15:24 <pfps> q+
19:15:24 <ericP> ... i'm not against supporting a subset of SHACL that works against remote SPARQL endpoints.
19:15:31 <ericP> ... we need a profile
19:16:00 <Arnaud> ack Dimitris
19:16:09 <ericP> ... given that some folks want to work with remote endpoints and others have a richer framework
19:16:52 <ericP> Dimitris: how is javascript related? it' can't see the graph
19:17:18 <Arnaud> ack pfps
19:17:46 <ericP> pfps: i'm hearing a claim that access to the data graph is necessary, which i don't believe is true.
19:18:23 <ericP> hknublau: things like accessing an RDF list of arguments.
19:18:29 <pfps> q_
19:18:33 <pfps> q+
19:19:00 <Arnaud> ack pfps
19:19:20 <ericP> ... it's clearly the fasted approach to have the data graph and the shapes graph in named graphs
19:19:39 <ericP> pfps: i'm not hearing an answer
19:19:39 <aryman> q+
19:19:46 <Arnaud> ack aryman
19:20:12 <ericP> aryman: we've accepted as a requirement that the core language be implemented in languages other than SPARQL.
19:20:21 <hknublau> q+
19:20:37 <ericP> ... every statement seems to be that it's easier, not that it's required.
19:20:39 <Arnaud> ack hknublau
19:20:48 <ericP> ... if it's required, we've lost language neutrality
19:21:15 <aryman> q+
19:21:38 <Arnaud> ack aryman
19:21:43 <pfps> there is a big difference between something that is necessary and something that is elegant or nice - if access to the shape graph is necessary for SHACL (particularly the core) then we need to have this access, if this is only elegant or nice then it is not necessary and may not be desirable
19:22:07 <ericP> hknublau: we could have an outer loop that does an SPO query, but maybe we want it more integrated
19:22:40 <ericP> q+
19:23:25 <Arnaud> ack ericP
19:23:55 <pfps> what is supposed to be worked out off-line?
19:25:59 <Dimitris> +q
19:26:10 <pfps> ericP: in ShEx there are both lists and recursion, but there is no access to the shapes graph during ShEx execution
19:26:28 <ericP> Arnaud: it would be odd if the core of the impl required a switch that not everyone implemented
19:26:34 <Arnaud> https://www.w3.org/2014/data-shapes/wiki/Main_Page#Useful_Working_Group_Wiki_pages_and_documents
19:26:36 <hknublau> @ericP ShEx doesn’t have templates, and this was my use case.
19:27:05 <hknublau> (Arguments such as lists of operands in AND and OR)
19:27:49 <pfps> I'm still not sure what is supposed to be worked out
19:27:49 <hknublau> q+
19:28:00 <Arnaud> ack Dimitris
19:28:01 <pfps> q+
19:28:22 <ericP> Dimitris: we need distinguish three things:
19:28:29 <ericP> ... .. specification
19:28:42 <ericP> ... .. access inside core
19:28:47 <ericP> ... access outside core
19:29:04 <hknublau> -q
19:29:07 <Arnaud> ack hknublau
19:29:33 <ericP> hknublau: i'm happy to start that wiki page
19:29:47 <Arnaud> ack pfps
19:29:57 <ericP> ... but i see many months going by [before FPWD]
19:30:14 <ericP> pfps: i see lots of "see ShEx" in this new document
19:30:44 <ericP> ... ShEx is an example of how to implement something very SHACL-like without access to the shapes graph
19:31:58 <Arnaud> trackbot, end meeting
19:31:58 <trackbot> Zakim, list attendees
19:31:58 <Zakim> sorry, trackbot, I don't know what conference this is
19:32:06 <trackbot> RRSAgent, please draft minutes
19:32:06 <RRSAgent> I have made the request to generate http://www.w3.org/2015/07/16-shapes-minutes.html trackbot
19:32:07 <trackbot> RRSAgent, bye
19:32:07 <RRSAgent> I see no action items