8 June 2006


Remote: Mike Dean, Peter Patel-Schneider, Alex Kozlenkov, Evan Wallace, Leora Morgenstern

Christian de Sainte Marie
gary hallmark, Piero Bonatti


<scribe> scribe: gary hallmark

<scribe> scribenick: GaryHallmark

csma: continue sorting based on degree of agreement

<sandro> ... and clarifying wording

widescale adoption/low cost of implementation/low transfer cost

(edited on-screen: slide 24 of http://www.w3.org/2005/rules/wg/wiki/F2F3?action=AttachFile&do=get&target=Goals%2C+CSF%2C+Requirements+%28final+version%2Blinks+to+minutes%29.ppt)

csma: widescale adoption/low cost of implementation/low transfer cost

sandro: split it up
... emphasize real time performance

daveR: why real-time goal?

paulV: means low deployment time cost
... low computation cost for consumer

<sandro> "Low Cost of Implementation" ==> cheap serialization

<sandro> small footprint? simple?

paulV: low complexity

<sandro> Latency is a different issue

piero: expressive RIF will yield shorter msgs

<AlexKozlenkov> Could anyone post the link to the very latest list of reqs? Thank you

<DavidHirtle> http://www.w3.org/2005/rules/wg/wiki/UCR/Critical_Factors_Analysis

piero: but expressive RIF may be more expensive to implement

<DavidHirtle> we're on

<AlexKozlenkov> Thanks David

csma: need further discussion for this requirement

<bonatti> ...and if RIF is expressive enough, one can encode his/her rule base in a compact way

<DavidHirtle> Alex, as we discuss them we are modifying some, but these modifications aren't viewable online (yet) unfortunately

<AlexKozlenkov> I see

<EvanWallace> numbering doesn't seem to match

<DavidHirtle> 1.2.3, within section 1

<DavidHirtle> (I know it's confusing)

csma: how to measure this requirment?

paulV: 1-10 seconds

<sandro> maybe: sub-second latency on transfer of practical 100-rule ruleset --- something like that.

<EvanWallace> got it

RIF should support RDF

csma: moving right along to new goal: consistency with W3C specs
... RIF should support RDF

(slide 25)

csma: RIF should accept RDF triples as data

paula: means rules work with RDF data

paulV: is this obligatory or just feature?

<AlexKozlenkov> Does it mean that RDF can be only in the body of the rules?

csma: what is relationship with SPARQL?

<DaveReynolds> (b) implicitly talks about RDF in head, we are currently talking about (a) which, yes, is about the body

sandro: RDF more integrated than blackbox SPARQL

sandro: need RDF in reactive rules not just Horn

sandro: all RIF dialects should accept RDF triples
... as data

<AlexKozlenkov> Gary, what about SQL data?

paulV: is RDF a requirement (mandatory?) of RIF or all rule languages using RIF?

<pfps> If the RIF can't handle Semantic Web data, then what is the RIF WG doing in the SW activity?

sandro: must all RIF dialects support integers?
... yes
... and so for RDF triples

csma: need more discussion

sandro: ambiguous: RDF Data Model vs RDF/XML Serialization

sandro: RDF brings along XML Schema datatypes

csma: rephrase to: RIF should support RDF data model?

daveR: if its in RIF core, its in all extensions, too

paulV: this is a strong constraint

chrisW: can't constrain all rule languages

sandro: need to define conformance

davidH: requirement is on RIF, not on rule languages

<sandro> sandro: If you want conformance to RIF, then you need to support ....

csma: again, needs more discussion

(slide 27)
... next: RIF should support RDF deduction rules
... Objection?
... Hearing none.

Axel: what does "cover" mean?

Sandro: e.g. RDF deductions available as additional RDF data

<sandro> So this is a shortcut for RIF Must Cover N3 / Jena Rules

Axel: ok

RIF should support OWL

(slide 28)
SPARQL queries covered this morning, Dave has action
... next: Support OWL - are issues here the same as with RDF data?

(slide 26)

kifer: is every OWL feature required?

josb: may depend on how it is integrated - e.g. like SWRL or more loosely

daveR: can't presuppose blackbox (loose) integration

<sandro> If blackbox approach to OWL integration, then this is the same as call-out. But not all support that.

josb: pfps may want to comment

sandro: need to resolve phasing to make more progress here, for ALL requirements

<sandro> pfps, you're not actually listening, are you?

kifer: what does it mean to include OWL subset relations in RIF?

ACTION: josb to disambiguate http://www.w3.org/2005/rules/wg/wiki/The_RIF_Core_must_be_able_to_accept_OWL_KBs_as_data

RIF should support XML

(slide 29)

csma: next: support XML

kifer: need more precise defn

paulV: often used by PR

sandro: map xml to prolog term

<sandro> mkifer: there's an approach where you use XML documents as templates

kifer: is this similar to xml extensions to SQL?

csma: can owl, rdf, and xml data be generalized to "data source"?

sandro: seems straightforward
... I think it's important to approve this requirement, as is

chrisW: RIF should handle interchange of XML data without translation
(slide 30)

<sandro> DaveR: yes, but also for RDF

chrisW: ditto for RDF and OWL

<AlexKozlenkov> I'm wondering if direct access to SQL should be allowed. That would allow us to tap into the world of industrial databases

sandro: There are two kinds of compatibility with RDF -- at the low model level, I want that in ALL dialects; at the detailed level it can be only in some dialects

DaveR: You can do useful pattern matching on XML documents"

csma: set of requirements around data sources and external calls (sparql, xslt, etc)
... should deal with them in a uniform way

<josb> scribenick: bonatti

permit XML info types to be expressed using XML schema

(slide 31)

csma: equivalent to supporting built-in XML elements?

<DavidHirtle> see: http://www.w3.org/TR/xmlschema-2/#built-in-datatypes

csma: (equivalent to David's point)

<DavidHirtle> (to avoid confusion)

<sandro> Charter: In Phase 1, the format must support literals and common functions and operators for at least: text strings (xsd:string), 32-bit signed integers (xsd:int), unlimited-size decimal numbers (xsd:decimal), Boolean values xsd:boolean), and list structures.

<sandro> 2.3.

<sandro> -- http://www.w3.org/2005/rules/wg/charter

Dave: need clarification

hassan: what extend of XML schema is to be supported?

sandro: more than elementary datatypes; charter mentions lists

dave: mentions restrictions to datatypes

csma: this needs to be clarified

<sandro> Clarify relationship to XS unions and restrictions on types

<DaveR:> RIF must be clear about which XS features are required for Conformance

RIF should cover LP + negation as failure and strong negation

(slide 33)

csma: next: RIF should cover LP + negation as failure and strong negation

csma:"strong negation" needs clarification

<sandro> "Strong Negation" is more related to 3-values, or maybe intuitionistic/constructive. No Excluded Middle.

MichaelK: strong negation is like classical negation but not quite

<sandro> summary: Strong Negation is like Classical Negation but without Law Of Excluded Model -- part of stable model semantics.

Piero: There is no interplay between positive and strongly-negated atoms. Strongly-negated atoms are like atoms re-written.

bonatti: strong negation can be "implemented" by replacing strongly negated atoms with new atoms uniformly
... puts no requirements on negation as failure (such as stratification)

<josb> strong negation is part of the answer set semantics, which in turn is based on the stable model semantics; strong negation is an extension of the stable model semantics

<sandro> DLV supports both

<sandro> => "strong negation" as in DLV

csma: let's use DLV as reference to specify what we mean

harlod: Wagner (REWERSE) has proposed/supported strong negation

sandro: isn't this good for phase 2?

<sandro> Handle this under Phase-2-RIFRAF.

csma: maybe such things should be discussed as a whole

<josb> THE reference on strong negation in logic programs, implemented in, e.g. DLV: http://citeseer.ist.psu.edu/gelfond91classical.html

module constructs for scoped positive and negationas failure queries

(slide 34)

harold: modules similar to contexts etc

scribe: efficiency is important

csma: can we propose concrete languages needing this?
... isn't this a property of a language, rather than RIF?

Josb: many languages (eg flora) have modules and have to be exchanged

harold: modules should be a requirement

<AlexKozlenkov> I have a question, should each individual rule have unique id? Also, if module id can be dynamically assigned, one could add/remove rulesets in one step.

sandro: working memory, a DBMS are example of scopes

<AlexKozlenkov> What I am saying is that rules may be accessed both individually and as groups

csma: needs discussion, strongly related, actually belongs to, RIFRAF

<sandro> PROPOSED: add a requirement that all features in RIFRAF are requirements

davidh: add a requirement saying that all prioritized features described in RIFRAF are to be covered by RIF

(slide 32)

<sandro> DaveR: We'll use RIFRAF to identify the features we cover

PROPOSED: RIFRAF will identify the set of languages to be covered by RIF

daveR: We'll use RIFRAF to identify the set of language features RIF may cover

PROPOSED: Every feature in RIFRAF will be discussed in the future as a possible Requirement.

harold: No -- they are orthogonal

<GaryHallmark> RIFRAF must be "larger" than the set of requirements (currently it is not, e.g. reactive rules)

PROPOSED: We will use RIFRAF to identify classes of language to be covered by RIF

PROPOSED: We will use RIFRAF to identify classes of languages to be covered by RIF

RESOLVED: We will use RIFRAF to identify classes of languages to be covered by RIF

<AlexKozlenkov> RIFRAF surely has more bearing on derivation rules

<AlexKozlenkov> Does not mean that RIFRAF will be extended to cover, say, reaction rules?

<sandro> AlexKozlenkov, what you're seeing is that RIFRAF right now only covers phase one -- Horn rules.

<DaveReynolds> Alex, yes I would say it should

<AlexKozlenkov> Can we explicitely mention that it will be extended, so that it is written down

<sandro> It should be in the minutes of the RIFRAF session earlier today, I think, Alex.

<AlexKozlenkov> OK, thanks, Sandro

tagging intended semantics

(slide 36)

already discussed

higher order and frame based syntax

(slides 37 and 38)

       2 requirements, moved to RIFRAF

harold: for each dimension there can be multiple choices - e.g. e.g. to support vs. not to support
... user/equality-defined functions (LIFE vs. Prolog)". This is an example where pointing to a RIFRAF
... dimension is not enough to express a design constraint: You have to say which value you pick
... in that dimension. For details see Hassan's email on logic with equality.
... not every combination of features in RIFRAF shall be supported

consistency w. major market technologies

(slide 39)

(editor: The numbers in the discussion below refer to the items in the "Full statement" section of http://www.w3.org/2005/rules/wg/wiki/Consistency_with_major_market_technologies)

chrisW: 1-3 look like requirements

gary: 1 and 2 similar to the data sources issue

csma: nobody really understands "UML Instances": it should be postponed

<sandro> Category -- data access by rules

chrisW: should we describe these languages as classes of RIFRAF features?

<sandro> "Data Sources"

<EvanWallace> Sound dropping out a lot

<AlexKozlenkov> I guess the mic is not being passed around really

<sandro> RIght. It's incredibly hard/expensive to pass the mic around, so we sometimes give up on it.

dave: let's move the SBVR point to RIFRAF and discuss "UML instances" and "ORM fact model populations"

gary: some languages can import business obj model from UML

csma: this has to do with sharing obj models - this is orthogonal

<AlexKozlenkov> Eclipse Ecore/EMF is one way to store UML instances, one can run OCL queries on it, one could also imagine a RIF integration

paulv: representing OCL as rules is an interesting topic, too

<AlexKozlenkov> OCL querying on EMF instances is actually quite cute

<AlexKozlenkov> Integrating EMF instances with RIF has value

meta-data for currency of rules

(slide 40)

somebody: refers to rule validity (in time)

csma: it has to do with rule management, not interchange

<AlexKozlenkov> I see

paulv: it is redundant - it could be done in rule languages that support time

hassan: no, it has rather to do with versioning

chrisW: the wiki page mentions "retrospective analysis"

paulv: such a "what-if" kind of reasoning is beyond the scope of RIF

dave: time validity could be part of the metadata (rule-tagging) effort

csma: discuss later with metadata

<sandro> Charter: RIF "must include a way to express facts as well as rules, and also metadata (annotations) about documents, facts, and rules. "

csma: having time validity means that a compliant application should ignore them if outside validity period

<AlexKozlenkov> There is a whole range of issues related to rules management. E.g., is RIF concerned with the rights management?

chrisW: not like "author" meta-tags: validity tags affect execution/reasoning

dave/csma: there is a requirement that RIF covers metadata: should we discuss it or just provide a mechanism to add metadata?

<AlexKozlenkov> One could say: limit inference to specific rules source/origin

<AlexKozlenkov> Extensible metadata should be a requirement. We cannot predict all the types of metadata people would want to associate with rules

gary: the question is about metadata in general

passing descriptive text through RIF

(slide 41)

somebody: i.e. something like comment tags

chrisW: if this just means "comments" then we all agree


metadata indicating exedcutability of rules

(slide 42)

<AlexKozlenkov> Aren't comments part of metadata?

somebody: needs further discussion

RIF scope - exchange of RDFS/OWL fact models

(slide 43)

davidh: only some of the issues here are requirements

csma: it duplicates previous discussion on data sources

gary: during last f2f facts were distinct from data

harold: data are not given any model-theoretic meaning

csma: it's in the data source discussion

4 modal operators

(slide 44)

csma: goes to RIFRAF


paula: Allen made a proposal not in the list of issues on design constraints: should it be discussed?
... it can be found in the e-mail archive

csma: it won't be in the draft to be produced on friday, so its discussion is postponed

csma: meet you all tomorrow at 8...

<sandro> Telephone: goodnight!

Summary of Action Items

[NEW] ACTION: josb to disambiguate http://www.w3.org/2005/rules/wg/wiki/The_RIF_Core_must_be_able_to_accept_OWL_KBs_as_data
[End of minutes]

Minutes formatted by David Booth's scribe.perl version 1.127 (CVS log)
$Date: 2006/06/17 20:13:49 $