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<ChrisW> http://lists.w3.org/Archives/Public/public-rif-wg/2009Mar/0129.html

<ChrisW> PROPOSED: accept last week's minutes

<ChrisW> RESOLVED: accept last week's minutes

Liason

<AdrianP> OWL2 has a new overview document

<AdrianP> OWL 2 Web Ontology Language Document Overview

<AdrianP> http://www.w3.org/TR/2009/WD-owl2-overview-20090327/

ChrisW: Liaisons, OWL, functions and predicates

Jos: I think that this (RDF text?) is not the right document for the functions and predicates; and there is an issue with reusing namespace

ChrisW: You think they should be in DTB then?

Jos: Yes

ChrisW: Does Axel agree?

Jos: Haven't talked to him yet about it

Sandro: I'm not sure they should go in DTB. There isn't really a good solution from a user's perspective. But at least if it's in DTB, OWL won't have to pay attention to it

ChrisW: Let's see what Axel thinks of this

<ChrisW> ACTION: chris to query axel on whether to move rdf:text F&Os to DTB [recorded in http://www.w3.org/2009/03/31-rif-minutes.html#action01]

<trackbot> Created ACTION-719 - Query axel on whether to move rdf:text F&Os to DTB [on Christopher Welty - due 2009-04-07].

Sandro: New document overview has been published by OWL, a roadmap and high level introduction

<sandro> http://www.w3.org/TR/owl2-overview/

ChrisW: We have talked about doing this for RIF also

<AdrianP> we have a little overview of RIF in the UCR document

<AdrianP> structure of RIF

<AdrianP> http://www.w3.org/2005/rules/wiki/UCR#Structure_of_RIF

F2F13

<ChrisW> http://www.w3.org/2005/rules/wiki/F2F13

ChrisW: Draft agenda for F2F13 is available, main objectives are to finalize the working drafts and bring them to last call
... there will be time to work on the documents at the meeting, and hopefully we will vote on last call at the meeting
... we will distinguish between issues to be addressed at the f2f and those to be postponed
... and we will go through test cases

<ChrisW> registration: http://www.w3.org/2002/09/wbs/38457/f2f13/

Sandro: DaveR, MikeD, Leora, Stella have not responded to the survey yet

<LeoraMorgenstern> I, and probably Stella, can't access that web page

<LeoraMorgenstern> If I can get a free hotel.

<LeoraMorgenstern> I do have some friends in Boston, so I'll see what I can do.

<ChrisW> great

Action review

ChrisW: action 707 - pending discussion
...action 716 - continued
...action 714 - continued
...action 708 - continued
...action 588 - continued

<LeoraMorgenstern> I got disconnected. Will call in again. Hold on.

<LeoraMorgenstern> Short answer: continued.

<LeoraMorgenstern> Long answer: I tried to access the issues pages, etc., and can't.

<LeoraMorgenstern> I need to access those pages. Can I get the permissions changed?

<LeoraMorgenstern> Okay, I'm back again.

ISSUE-67

<sandro> issue-67?

<trackbot> ISSUE-67 -- need string predicates string-less-than, etc. (waiting on PS) -- OPEN

<trackbot> http://www.w3.org/2005/rules/wg/track/issues/67

ChrisW: string-less-than predicate, discussed at telecon late last year
... if we have this predicate is would be easier to map "<" in the PS to the predicates

Sandro: problem with a multi-typed < comparator

ChrisW: We could then abandon this issue, or do some extra work to find how different existing rule systems handle this

GaryH: XPath?

<Michael_Kifer> Prolog has @< for non-numeric comparison.

ChrisW: The current issue is that since RIF is dynamically typed, mapping the "<" in PS to XML may be complicated

Sandro: And also whether we should have it, since XPath dosn't have it

Jos: I think we should drop the redundant items, string-less-than, string-greater-than, string-equal-to...

<josb> http://www.w3.org/2005/rules/wiki/DTB#pred:matches_.28adapted_from_fn:matches.29

ChrisW: Anyone else want to drop them? ... (no one)
... anyone want to keep them, Sandro, GaryH?

<josb> no

Sandro: I think a lot of people will have to implement the more general predicate anyway

ChrisW: Issue-67 has 2 parts. 1. DTB string compare predicates. 2. whether to have general compare predicates
... Jos, do you feel strongly about part 1, about getting rid of the string specific compares?

Jos: Yes. XPath did a pretty good job of defining operators for comparing, and I think following them is a good idea

GaryH: I think XPath is not good in some ways, and that we shouldn't necessarily just adopt it

ChrisW: GaryH, would you object to dropping them?

GaryH: No

<ChrisW> PROPOSED: drop string<, string> etc. from DTB

ChrisW: Would anyone else object to the proposal above? (no one) ....We will vote next week

<ChrisW> ISSUE: Should we have a more general "literal-less-than" (etc.) predicate that covers < tests for all literals.

<trackbot> Created ISSUE-96 - Should we have a more general \"literal-less-than\" (etc.) predicate that covers < tests for all literals. ; please complete additional details at http://www.w3.org/2005/rules/wg/track/issues/96/edit .

<ChrisW> straw poll: -1 object ... +1 would do work to make it happen

<sandro> +1 add literal-less-than, so the PS can have a ">", etc.

<DaveReynolds> +0.1

<josb> -0.9

<ChrisW> +.1

<LeoraMorgenstern> .3

<Michael_Kifer> +0.1

<AdrianP> +0.2

<Gary> 0

<mdean> +0.1

<Harold> +.3

<LeoraMorgenstern> +0.3

JosB: Reason for not supporting the proposal is redundancy and diversion from XPath

Sandro: We have a reason to divert from XPath becase we have a different execution model
... and it would be a big benefit in the PS

Jos: Could use a more complicated scheme to map PS to XML

ChrisW: We resolved that the PS should map directly 1-1 to the XML

GaryH: What happens in RIF if two different types of things are compared?

Sandro: Undefined truth value, and implementation can raise an error

ChrisW: Sandro, are you willing to edit DTB to define these predicates?

<ChrisW> ACTION: Sandro to add definition of literal-< (etc) to DTB [recorded in http://www.w3.org/2009/03/31-rif-minutes.html#action03]

<trackbot> Created ACTION-720 - Add definition of literal-< (etc) to DTB [on Sandro Hawke - due 2009-04-07].

<sandro> (where it is NOT yet agreed to keep it.... but there is a SLIGHT WG leaning towards it)

ISSUE-80

ChrisW: I edited DTB to add the predicate that I think we agreed on
... I removed predicate-literal-equals, changed name, used CamelCase, changed description of semantics of LiteralNotIdentical
... see introduction to section 3.1.1

<LeoraMorgenstern> Can you c&p the issue, since I can't access it?

<ChrisW> http://www.w3.org/2005/rules/wiki/DTB#Comparison_for_Literals

<Harold> http://www.w3.org/2005/rules/wiki/index.php?title=DTB&diff=7950&oldid=7674

Jos: Question about use of the term "dialect at hand," not sure "dialect" is adequately defined

ChrisW: The wording "dialect at hand" is used throughout the document

DaveR: Clarification about disjoint types

<mdean> i have another telecon - bye

<Harold> Span of Chris' changes: http://www.w3.org/2005/rules/wiki/index.php?title=DTB&diff=7961&oldid=7674

<ChrisW> PROPOSED: Accept changes reflected in DTB version [http://www.w3.org/2005/rules/wiki/index.php?title=DTB&oldid=7961], closing issue-80

ChrisW: If we agree to this wording, it will close issue-80

Jos: I had an action to see how this change would affect the OWL-RL ruleset, and I am not convinced that it makes it possible to write a RIF-core axiomatization of OWL-RL
... and I think that was the motiviation for this predicate

<josb> l1[differentFrom -> l2]

Jos: RIF core has to be safe, so literals must be introduced in some other place so you can refer so them in the rule body

DaveR: You can write it in the frame syntax

Jos: Discussion about literals...will need to take into account all literals in the vocabulary, even ones that aren't mentioned in the ontology

<josb> 1[differentFrom -> 2]

Sandro: I don't see this as a problem

Jos: Won't be able have a generic ruleset; will need to use information from the OWL ontology

ChrisW: Doesn't this point also hold for the ruleset without this predicate?

Jos: Yes

ChrisW: And having this predicate does reduce the size of the ruleset from quadratic to linear, which is significant.

Jos: I would not object to this

<ChrisW> PROPOSED: Accept changes reflected in DTB version [http://www.w3.org/2005/rules/wiki/index.php?title=DTB&oldid=7961], closing issue-80

<sandro> +1

<josb> 0

<ChrisW> +1

<Harold> +1

<DaveReynolds> +1

<LeoraMorgenstern> +1

<Michael_Kifer> 0

<Gary> 0

<AdrianP> +1

<ChrisW> RESOLVED: Accept changes reflected in DTB version [http://www.w3.org/2005/rules/wiki/index.php?title=DTB&oldid=7961], closing issue-80

<josb> (assuming the resolution only pertains to the definition of isLiteralNotIdentical))

<ChrisW> ACTION: Chris to close issue-80 [recorded in http://www.w3.org/2009/03/31-rif-minutes.html#action04]

<trackbot> Created ACTION-721 - Close issue-80 [on Christopher Welty - due 2009-04-07].

ChrisW: Safeness of OWL-RL and Core should be explained somewhere, i.e. the fact that you need to ground these literals

<ChrisW> issue-80?

<trackbot> ISSUE-80 -- Should we extend DTB to include more general builtins -- OPEN

<trackbot> http://www.w3.org/2005/rules/wg/track/issues/80

<josb> http://www.w3.org/2005/rules/wiki/SWC#Embedding_RIF-OWL_2_RL_Combinations

Jos: I don't think this text (Chris' comment above) belongs in SWC

Sandro: It should be explained in the embedding appendix

Jos: I wouldn't know what other text to put there

Sandro: How does the embedding compare to the OWL RL ruleset, is it sound and complete?

Jos: Yes, it is. In a RIF-OWL combination where the RIF ruleset is empty, I'm not sure if there would be any entailments that wouldn't be derived from the OWL ontology alone

ChrisW: Let's move this discussion to email

<ChrisW> ACTION: Dave to update OWL-RL document to reflect discussion on safeness (esp. in light of new nonidential preciate) [recorded in http://www.w3.org/2009/03/31-rif-minutes.html#action05]

<trackbot> Created ACTION-722 - Update OWL-RL document to reflect discussion on safeness (esp. in light of new nonidential preciate) [on Dave Reynolds - due 2009-04-07].

Coreifying SWC

ChrisW: Jos, you raised an issue about making SWC valid for Core. Where do we stand on this?

Jos: I suggest to define the embedding only for the case where it is embeddable into Core.

ChrisW: And this can be checked statically?

Jos: Yes

ChrisW: Anyone have any questions or concerns about this?

<ChrisW> ACTION: josb to COREify SWC document [recorded in http://www.w3.org/2009/03/31-rif-minutes.html#action06]

<trackbot> Created ACTION-723 - COREify SWC document [on Jos de Bruijn - due 2009-04-07].

Jos: wrt coreifying, there is an issue with equality....will need to either have equality, or axiomatize it
... could either define embedding only for BLD, or can restrict to equality-free part of OWL2-RL
... I prefer to define it only for BLD
... there are many useful OWL2-RL statements that use equality, so I'd rather not disallow them in the embedding

<Michael_Kifer> Equality does not add expressiveness only if the arities are bound, like in OWL. In general you need an infinite number of axioms.

ChrisW: For embedding in Core we can have a syntactic restriction....

Sandro: Use axioms for equality in core embedding

MichaelK: You cannot axiomatize equality in core

Jos: It would depend on the predicates that are actually used in the ruleset, so it's actually an embedding not an axiomatization

<ChrisW> ACTION: josb to summarize core-ifying owl in email [recorded in http://www.w3.org/2009/03/31-rif-minutes.html#action07]

<trackbot> Created ACTION-724 - Summarize core-ifying owl in email [on Jos de Bruijn - due 2009-04-07].

AOB

<ChrisW> aob?

ChrisW: Adjourned