17:57:28 <RRSAgent> RRSAgent has joined #shapes
17:57:28 <RRSAgent> logging to http://www.w3.org/2016/03/17-shapes-irc
17:57:30 <trackbot> RRSAgent, make logs rdf-data-shapes
17:57:30 <Zakim> Zakim has joined #shapes
17:57:32 <trackbot> Zakim, this will be SHAPES
17:57:32 <Zakim> I do not see a conference matching that name scheduled within the next hour, trackbot
17:57:33 <trackbot> Meeting: RDF Data Shapes Working Group Teleconference
17:57:33 <trackbot> Date: 17 March 2016
17:58:09 <Arnaud> agenda: https://www.w3.org/2014/data-shapes/wiki/Meetings:Telecon2016.03.17
17:58:14 <Arnaud> chair: Arnaud
18:01:09 <Arnaud> present+
18:01:18 <simonstey> present+
18:01:45 <Dimitris> Dimitris has joined #shapes
18:01:47 <hknublau> hknublau has joined #shapes
18:01:54 <BartvanLeeuwen> BartvanLeeuwen has joined #shapes
18:02:48 <hknublau> present+
18:03:05 <pfps> pfps has joined #shapes
18:03:08 <pfps> present+
18:03:46 <Dimitris> present+
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18:04:40 <hsolbrig> present+ hsolbrig
18:05:22 <simonstey> scribe: simonstey
18:05:55 <simonstey> topic: Admin
18:05:45 <Arnaud> PROPOSED: Approve minutes of the 10 March 2016 Telecon: http://www.w3.org/2016/03/10-shapes-minutes.html
18:05:53 <pfps> minutes look OK
18:06:35 <Arnaud> RESOLVED: Approve minutes of the 10 March 2016 Telecon: http://www.w3.org/2016/03/10-shapes-minutes.html
18:07:09 <simonstey> TOPIC: Disposal of Raised Issues
18:07:22 <Arnaud> PROPOSED: Open ISSUE-134 knowing inverse, ISSUE-135 and/or syntactic sugar, ISSUE-136 Property pair names, ISSUE-137 language tag
18:07:37 <hknublau> +1
18:07:45 <simonstey> +1
18:07:45 <kcoyle> +1
18:07:51 <Dimitris> +1
18:07:51 <hsolbrig> +1
18:07:53 <ericP> +1
18:08:11 <Arnaud> RESOLVED: Open ISSUE-134 knowing inverse, ISSUE-135 and/or syntactic sugar, ISSUE-136 Property pair names, ISSUE-137 language tag
18:08:17 <simonstey> TOPIC: ISSUE-80: Scheme URIs
18:08:21 <simonstey> issue-80
18:08:21 <trackbot> issue-80 -- Constraint to limit IRIs against scheme/namespace, possibly with dereferencing -- open
18:08:21 <trackbot> http://www.w3.org/2014/data-shapes/track/issues/80
18:08:51 <simonstey> Arnaud: we talked about it last week; eric sent out an email about how stem works in shex.. where do we stand now?
18:09:14 <jamsden> jamsden has joined #shapes
18:09:29 <simonstey> ericP: was I about to send a proposal on how this would look like in shacl?
18:10:20 <simonstey> Arnaud: thought this would be a low hanging fruit
18:11:01 <simonstey> TOPIC: ISSUE-129
18:11:05 <simonstey> issue-129
18:11:05 <trackbot> issue-129 -- Existential constraints should be consistent -- open
18:11:05 <trackbot> http://www.w3.org/2014/data-shapes/track/issues/129
18:11:50 <simonstey> Arnaud: dimitris raised that issue
18:12:22 <simonstey> ... we should spend little bit of time discussing it; some votes were already cast
18:12:59 <simonstey> Dimitris: the definition of extential constraints might not be the best one
18:13:16 <pfps> q+
18:13:16 <simonstey> ... but e.g. hasValue works different from other constraint types in shacl
18:13:52 <simonstey> ... while others only work over exisiting values, this does not
18:14:20 <simonstey> pfps: holger had a perfect description for that
18:14:50 <simonstey> ... i see no possibility of changing the meaning of hasValue since it works exactly as it should
18:15:30 <simonstey> Arnaud: so you are saying there is nothing to be fixed?
18:15:33 <Arnaud> ack pfps
18:16:04 <simonstey> pfps: no.. espec. the meaning of the newer ones need some fiddling
18:17:03 <simonstey> ... the problem doesn't go away if you get rid of the existential ones
18:18:13 <simonstey> ... e.g., equals, minCount have a clear meaning and people would scream at us if we change it
18:18:51 <simonstey> ericP: i'm wondering whether people actually understand the implications of what you are saying?
18:19:49 <Dimitris> q+
18:19:53 <simonstey> pfps: when people do db querying, they get confused if they get no answers for a query
18:20:50 <simonstey> Arnaud: example: there must not be a property with a certain value less than x
18:21:10 <Arnaud> ack Dimitris
18:21:11 <simonstey> ... does the value need to exist?
18:21:29 <simonstey> Dimitris: this is not an implementation issue; that's the easy part
18:21:59 <simonstey> ... I was worried about users actually understanding the meaning of hasValue
18:22:32 <simonstey> ... it could e.g., be changed to sh:requiredValue
18:22:44 <jamsden> q+
18:22:48 <pfps> The definition for hasValue is "The property sh:hasValue can be used to verify that the focus node has a given RDF node among the values of the given predicate. "  This seems to be very obvious.
18:22:51 <Arnaud> ack jamsden
18:22:53 <pfps> q+
18:23:23 <simonstey> jamsden: what's the confusion here?
18:23:54 <pfps> For sh:in "The property sh:in exclusively enumerates the values that a property may have. When specified, each value of the given property must be a member of the specified list. "
18:24:06 <Arnaud> ack pfps
18:24:06 <pfps> Both seem quite obvious and the right definition
18:24:14 <kcoyle> q+
18:24:22 <simonstey> pfps: there is no such thing as undefined in SPARQL
18:24:33 <simonstey> ... it's there or not
18:25:00 <ericP> q+
18:25:17 <Dimitris> q+
18:25:28 <Arnaud> ack kcoyle
18:25:32 <simonstey> ... the current definitions seem pretty obvious to me
18:25:37 <simonstey> jamsden: same for me
18:26:09 <Dimitris> Jim, the problem is that  sh:in ("foo") and sh:hasValue "foo" behave differently
18:26:11 <pfps> In RDF values are not associated with properties.
18:26:13 <pfps> q+
18:26:46 <simonstey> kcoyle: the cardinality constraints are on the property and not the value, right?
18:26:54 <hsolbrig> how about "includesValue"
18:27:14 <simonstey> pfps: in shacl, everytime you are doing something you have a property in hand
18:27:26 <hsolbrig> "has" tends to be fuzzy whether we're dealing with a set or an individual
18:27:44 <Arnaud> ack pfps
18:27:50 <hsolbrig> or, to be more orthogonal with "in", just "has"
18:28:10 <ericP> { [ sh:predicate :foo; sh:hasValue 1; sh:hasValue 2 ] } \ { <s> :foo 1,2,3 }
18:28:10 <hsolbrig> s/"has"/"includes"/
18:28:44 <hsolbrig> +q
18:28:45 <ericP> { [ sh:predicate :foo; sh:in ( 1 2 ) ] } \ { <s> :foo 1,2,3 } => fail
18:29:08 <simonstey> pfps: e.g. sh:in looks at each of the values separately (for each of those values..)
18:29:32 <ericP> +1 to harold's proposal
18:29:42 <ericP> though i'm curious about use cases for this
18:29:44 <simonstey> ... minCount on the other hand works over the whole set of properties
18:29:57 <ericP> maybe ditch sh:hasValue ?
18:30:22 <Arnaud> ack ericP
18:30:48 <simonstey> ... two triples that have the same S, P but different Os resemble something like multivalued properties
18:31:17 <Dimitris> q-
18:31:44 <simonstey> q+
18:31:56 <Arnaud> ack simonstey
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18:32:31 <hknublau> hasValue is very common in filters
18:32:48 <Arnaud> ack hsolbrig
18:32:50 <kcoyle> I think hasValue has lots of uses -- unless I misunderstand it
18:33:17 <pfps> I agree with Holger that hasValue would be very common in filters
18:34:19 <simonstey> hsolbrig: the confusion comes from the fact that its meaning can be understood as "its value includes"
18:34:34 <simonstey> ... or "its value is"
18:35:11 <ericP> hknublau, can you describe how hasValue is used in filters?
18:35:23 <simonstey> q+
18:35:37 <Arnaud> ack simonstey
18:36:20 <hknublau> "Every person who has bornIn = USA must not travel to Cuba"
18:36:56 <simonstey> Arnaud: so how do we make progress here?
18:37:25 <simonstey> pfps: whoops.. my proposal is simple -> do nothing
18:38:22 <simonstey> Arnaud: lets give it another week, there is no rush on closing now
18:38:36 <Labra> present+ labra
18:39:04 <simonstey> topic: Type, instance, subclass in SHACL documents
18:39:40 <simonstey> Arnaud: there was extensive discussion on that on the mailing list
18:39:53 <simonstey> issue-65
18:39:53 <trackbot> issue-65 -- Consistency and cohesiveness of nomenclature (e.g., shapes, scopes, and constraints) -- open
18:39:53 <trackbot> http://www.w3.org/2014/data-shapes/track/issues/65
18:39:55 <simonstey> issue-120
18:39:55 <trackbot> issue-120 -- The spec must be more precise and consistent about when a resource is a shape, a class, and an instance of a class -- closed
18:39:55 <trackbot> http://www.w3.org/2014/data-shapes/track/issues/120
18:40:15 <simonstey> ... those issues might be related to that topic
18:41:32 <simonstey> pfps: I'm pretty sure that SPARQL isn't using "instance" anywhere in its spec
18:41:34 <Dimitris> \me sparql says "for instance..."
18:41:59 <Dimitris> s/me sparql says "for instance..."//
18:42:26 <simonstey> hknublau: we certainly need to improve the wording
18:42:41 <ericP> pfps, SPARQL 1.1 uses instance for the notion of "instance mapping"
18:42:48 <ericP> (and a few instances of "for instance")
18:43:18 <simonstey> ... we have some redudancies in the document that where meant to support understanding but might ended up confusing people
18:44:19 <pfps> the overhead will be about 100 words in a long document
18:44:20 <simonstey> ... I do not agree with pfps that we are violating any ???
18:45:07 <simonstey> Arnaud: we need to make sure that the spec isn't wrong
18:46:10 <simonstey> ... for me the downside of pfps' proposal is that it might be a bit painful of having to write "SHACL instance" everytime
18:46:27 <pfps> q+
18:46:32 <simonstey> ... but at the same time I'm sensitive to his proposal
18:46:39 <Arnaud> ack pfps
18:46:48 <simonstey> ... since people might not read the document from the beginning to the end
18:47:33 <Dimitris> q+
18:47:38 <Arnaud> ack Dimitris
18:47:43 <simonstey> pfps: I think we need to be cristal clear about the difference between SHACL instance and RDF(S) instance
18:48:23 <simonstey> Dimitris: we could try to remove all uses of instance, but we've to see
18:49:18 <simonstey> s/cristal/crystal
18:49:37 <simonstey> Arnaud: Syntax and metamodel Complexity and Possible simplifications
18:49:47 <simonstey> s/Arnaud:/Topic:
18:51:03 <simonstey> pfps: I found a hole in the metamodel.. which is kind of disturbing
18:51:07 <hknublau> q+
18:51:47 <simonstey> ... when a property is both a target of a inversepropertyconstraint as well as a propertyconstraint, it behaves strange
18:52:54 <simonstey> [... pfps writing down an example ...]
18:53:04 <pfps> sh:shape sh:property [ a sh:InversePropertyConstraint ; sh:predicate ex:foo ; sh:minCount 2 ]
18:54:26 <simonstey> [ericP & pfps discussing the example]
18:54:26 <Arnaud> ack hknublau
18:54:38 <ericP> validating <X> as the above:
18:54:43 <simonstey> hknublau: it's unfinished but not broken
18:55:00 <simonstey> ... both of your examples are invalid shape graphs
18:55:14 <pfps> sh:shape sh:property [ a sh:PropertyConstraint ;a sh:InversePropertyConstraint ; sh:predicate ex:foo ; sh:minCount 2 ]
18:55:18 <ericP>   <Y> :foo <X>. <Z> :foo <X>. <X> :foo <Y>. <X> :foo <Z> .
18:55:24 <simonstey> ... what we could do is, making propertyconstraint and inversepropconstraint disjoint
18:56:25 <simonstey> ... so a constraint can't be both at the same time
18:56:40 <ericP>   <Y> :foo <X>. <Z> :foo <X>. <X> :foo <W>. <X> :foo <K> .
18:57:38 <simonstey> ericP: in shex we just have a flag that says whether something is forwards or backwards
18:58:55 <simonstey> pfps: people can do a lot of silly, stupid and/or smart things in RDF
19:00:53 <simonstey> ... you don't want to have to deal with defending your syntax against stupid/silly/.. proposals just because you weren't explicit enough in specifying what's allowed and what's not
19:01:21 <simonstey> Arnaud: I want people to investigate pfps proposal
19:01:59 <ericP> pfps, did OWL address this by saying that a parsing OWL from RDF fails if there is more than one way to parse it?
19:02:19 <iovka> iovka has joined #shapes
19:02:22 <simonstey> ... I think pfps has made a fair amount of effort in providing information about his proposal
19:02:34 <pfps> OWL solves this problem by making string requirements on graphs that are valid OWL ontologies
19:02:48 <Arnaud> https://www.w3.org/2014/data-shapes/wiki/ISSUE-95:_Metamodel_simplifications#Proposal_4
19:03:26 <pfps> I believe that Holdger said that syntax with positional arguments was an anti-pattern
19:03:30 <simonstey> ... I want to step back from discussing specific issues and discuss pfps proposal
19:04:12 <simonstey> ericP: maybe pfps wants to give us a short description of his proposal now?
19:04:52 <ericP> https://www.w3.org/2014/data-shapes/wiki/ISSUE-95:_Metamodel_simplifications#Proposal_4
19:06:09 <simonstey> pfps: 1) sh:property/invprop. you have to pull out the property and put it in a list; the benefit is that you don't have to worry about not knowing in which direction you have to go
19:07:01 <simonstey> ... 2) sh:pattern is a little bit odd right now
19:07:12 <ericP> current: ex:MyShape a sh:Shape ; sh:constraint [ a sh:Shape ; sh:predicate ex:myProperty ; sh:class ex:Person ; sh:in ( ex:Susan ex:Bill ) ] .
19:07:15 <ericP> pfps: ex:MyShape a sh:Shape ; sh:fillers ( ex:myProperty [ a sh:Shape ; sh:class ex:Person ; sh:in ( ex:Susan ex:Bill ) ] ) .
19:08:05 <ericP> current: ex:MyShape a sh:Shape ; sh:property [ a sh:Shape ; sh:predicate ex:myProperty ; sh:class ex:Person ; sh:in ( ex:Susan ex:Bill ) ] .
19:08:08 <ericP> pfps: ex:MyShape a sh:Shape ; sh:propValue ( ex:myProperty [ a sh:Shape ; sh:class ex:Person ; sh:in ( ex:Susan ex:Bill ) ] ) .
19:08:47 <simonstey> ... you can't have two properties inside the square brackets to combine together
19:09:24 <simonstey> ... currently it's painful to repeat things
19:10:30 <simonstey> ... 3) you can actually put e.g. sh:minCount anywhere in the shape
19:10:44 <ericP> ex:PersonShape sh:minCount 1e10 .
19:11:29 <simonstey> ... there are no more node/property/invpropertyconstraints anymore
19:11:55 <simonstey> ... there are only shapes; very similar to shex
19:14:44 <simonstey> Arnaud: I'm wondering whether the WG thinks we should spend time on looking into this or not
19:15:15 <Arnaud> STRAWPOLL: continue investigating Peter's proposal there may be something there (+1: agree, 0: not sure, -1: disagree)
19:15:18 <ericP> +1
19:15:19 <hsolbrig> +1
19:15:19 <simonstey> +1
19:15:20 <hknublau> -1
19:15:22 <Labra> +1
19:15:22 <kcoyle> +1
19:15:26 <pfps> +1 (surprise!)
19:15:45 <Dimitris> 0- ( I think there are good elements but not user friendly)
19:16:03 <jamsden> +0
19:16:08 <simonstey> but we might adopt some bits and pieces
19:16:26 <pfps> I note that I have updated my previous SHACL implementation for this new syntax.  It is about 80% complete.
19:16:32 <jamsden> I don't see the motivation for such a significant change at this late date
19:17:27 <pfps> to be fair, RDF makes for complex, long, and hard-to-understand syntax
19:18:10 <jamsden> these issues just aren't that compelling to me
19:18:54 <jamsden> what is the process for assessing, evaluating and deciding on a resolution?
19:19:00 <simonstey> Arnaud: I encourage everybody to have a read on pfps proposal
19:19:09 <simonstey> TOPIC: Comparative expressiveness of ShEx and SHACL
19:19:29 <simonstey> iovka's email: https://lists.w3.org/Archives/Public/public-data-shapes-wg/2016Mar/0219.html
19:19:52 <simonstey> document: https://hal.archives-ouvertes.fr/hal-01288285/document
19:20:29 <simonstey> iovka: I'm a formal methods person; so in order to understand SHACL I generated an abstraction of SHACL
19:21:33 <simonstey> ... I used presburger arithmetics for caputring shex (not needed for shacl)
19:21:44 <simonstey> s/caputring/capturing
19:22:28 <simonstey> iovka: future goal is to come up with a transformation between shex <-> shacl
19:23:45 <simonstey> ... I would need some support from someone who's more familiar with shacl than me for checking whether I captured shacl correctly or not
19:25:01 <pfps> q+
19:25:10 <Arnaud> ack pfps
19:25:14 <simonstey> Arnaud: I'm quite grateful on what iovka is doing
19:25:41 <iovka> q+
19:26:25 <Arnaud> ack iovka
19:26:35 <simonstey> pfps: the reason why I jumped on hasValue is that I'm not sure whether the current formalism is actually capable of capturing it (haven't looked at it though)
19:27:19 <simonstey> iovka: I had a brief look at it today and it appears to be one of the easiest constraints
19:27:33 <ericP> iovka expressed [] sh:hasValue 1 can be captured in ShEx as <S> EXTRA :foo { :foo [1] }
19:27:53 <ericP> s/can be captured in/as/
19:28:49 <pfps> my time is likely to be very limited for a while starting very soon now
19:29:45 <simonstey> I will have a read
19:30:42 <Arnaud> trackbot, end meeting
19:30:42 <trackbot> Zakim, list attendees
19:30:42 <Zakim> As of this point the attendees have been Arnaud, simonstey, hknublau, pfps, Dimitris, hsolbrig, labra, kcoyle, ericP, jamsden, iovka
19:30:43 <iovka> quit
19:30:50 <trackbot> RRSAgent, please draft minutes
19:30:50 <RRSAgent> I have made the request to generate http://www.w3.org/2016/03/17-shapes-minutes.html trackbot
19:30:51 <trackbot> RRSAgent, bye
19:30:51 <RRSAgent> I see no action items