See also: IRC log
<csma> item+ Admin
<csma> item+ Liaison
<csma> item+ Public comments
<csma> item+ Action review
<csma> item+ Safeness
<csma> item+ issue 80 (meta-builtins)
<csma> item+ issue 81 (OWL-RL datatypes)
<csma> item+ issue 90 (rif:iri and rdf:text in RDF graphs)
<csma> item+ test cases
<csma> item+ AOB
<csma> Adrian, will you scribe?
<csma> scribe: Adrian Paschke
Zakim seems to have a problem
<csma> Scribenick: AdrianP
<ChrisW> kick zakim #rif
<AxelPolleres> trying to dial in
<ChrisW> Attendence: Christian, ChrisW, Changhai, Jos, Leora, Harold, Adrian, Gary, DaveR, Stella
<ChrisW> Attendees: Christian, ChrisW, Changhai, Jos, Leora, Harold, Adrian, Gary, DaveR, Stella
<ChrisW> Attendees: Christian, ChrisW, Changhai, Jos, Leora, Harold, Adrian, Gary, DaveR, Stella, Sandro
<csma> next item
<AxelPolleres> I am here as well
<ChrisW> Attendees: Christian, ChrisW, Changhai, Jos, Leora, Harold, Adrian, Gary, DaveR, Stella, Sandro, Axel
<csma> item agenda
<scribe> scribe: Adrian Paschke
<scribe> scribe: AdrianP
<csma> PROPOSED:* accept minutes of F2F12
csma: accept minutes of F2F12
csma: no objection - resolved
<csma> RESOLVED: accept minutes of F2F12
csma: accept minutes Jan. 20
<csma> PROPOSED: to accept the minutes of Jan 20
<csma> RESOLVED: to accept the minutes of Jan 20
<csma> PROPOSED: to accept the minutes of Jan 27
<csma> RESOLVED: to accept the minutes of Jan 27
ChrisW: share common semantics
for datatypes between OWL WG and RIF WG
... discuss if there can be one common set of datatypes
Axel: SPARQL working group just
... I'm chairing it
... will forward the link to the new charter
... liaison makes sense - first phase: SPARQL updates
... valuable work done in RIF SWC
... time schedules for SPARQL WG will be discussed next week
csma: Axel liaison for SPARQL
<AxelPolleres> Let me know if someone else is joining (will see that anyways)
Adrian: HCLS currently looks into federated SPARQL queries
<AxelPolleres> SPARQL charter: http://www.w3.org/2009/01/sparql-charter.html
Adrian: and linked open data
Axel: F2F13 at WWW09
... would be in Europe
... talked to my former affiliation
... reachable by Metro (but outside of Madrid)
... problem might be speaker phone
<DaveReynolds> I would almost certainly need to phone in.
Axel: we rely on what the university can offer
Can we use Voice over IP?
csma: will discuss it further with Sandro and Chris
Axel: might be possible to attend
... Have it collocated with the W3C AC meeting in Boston
csma: many other constraints AAAI meeting, OMG meeting
<sandro> According to http://www.w3.org/2002/09/wbs/38457/f2f13_dates/results, everyone said they could attend in Boston April 15-17
csma: action review
csma: 700 closed
... 697 closed
csma 695 closed
csma 695 continued
csma 954 (not 695) continued
csma 693 closed
<sandro> action-693 closed
<trackbot> ACTION-693 Push back on OWL-WG about disjoint value spaces closed
<trackbot> ACTION-690 Specify core as a specialisation of PRD closed
<trackbot> ACTION-688 Write some safeness test cases closed
<trackbot> ACTION-687 Write a proposed new definition of the safeness restriction closed
<trackbot> ACTION-685 Write a test case or two to illiustrate how ## and rdfs:subClassOf relate closed
<csma> to add a version of http://www.w3.org/2005/rules/wiki/RDF_Combination_Constant_Equivalence_2 with the import having a ^^xs:string
<trackbot> ACTION-684 to add a version of http://www.w3.org/2005/rules/wiki/RDF_Combination_Constant_Equivalence_2 with the import having a ^^xs:string closed
<trackbot> ACTION-683 Ask Dave to have a look at ISSUE-81 before F2F12 closed
<trackbot> ACTION-682 Edit ISSUE-81 to explain the technical reason that make owl:real, xsd:hexBinary, xsd:base64Binary incompatible with RIF current data types closed
<trackbot> ACTION-681 Update DTB to reflect resolution on guards closed
<ChrisW> action-681 pending review
Sandro: did action-579
csma: pending review actions
<sandro> action-579 closed
<trackbot> ACTION-579 Implement RIF-XML to PS translator closed
<ChrisW> action-631 closed
<trackbot> ACTION-631 Make a positive syntax test version of Argument names not Const closed
<ChrisW> action-664 closed
<trackbot> ACTION-664 Figure process for RDF errata (re: fixing rdf:xmlliteral) closed
<ChrisW> what a productive week!
Jos: error with equality in the
body - was to liberal - fixed it
... hard to read - tried to make it more readable
Jos: context is condition
... safeness is defined relativ to a context
... you need to consider context to decide if a variable is safe
cmsa: isn't it too general for Core?
Jos: necessary because of = in the body
<josb> x=z and p(z)
you want z to be safe
harold: if you have x=z it is not recursively safe
<AxelPolleres> x=y y=z z=x works with your def, jos?
Axel: cyclic equality adressed?
Jos: right that is the idea
csma: leave defintion as is?
ChrisW: wondering if context should be on the quantification formula not on implication formulas?
Jos: in the quantifier you might
have variables which are not used in the rule
... you have to distinguish two cases "used in rule" and "not"
... universial rule - if variable is never used it does not make the rule unsafe
<AxelPolleres> for the records, the definition allows infinite extensions of predicates, but we had discussed that on the mailinglist.
<josb> x+y = y
<josb> x+y = z
<csma> P(?x) :- pred:greater-than(func:numeric-add(?x 1) 0)
<josb> p(x) q(y)
Jos: first 6 bullets ignore built-ins
Axel: we discussed termination vs. non-termination in forward reasoning
<AxelPolleres> a(Y) :- a(X), func:numeric-add(X,1) = Y.
Jos: need to revise it again to cover this
Sandro: try a pseudo code version of this
Jos: will first revise it and make it easier to understand
<cke> The old definition looks to be more understandable. Can we adapt it?
csma: isn't there an accepted definition of safeness
Axel: yes, but only for
... not for built-ins
<ChrisW> ACTION: jos to correct safeness definition (wrt mapping for variables) [recorded in http://www.w3.org/2009/02/03-rif-minutes.html#action01]
<trackbot> Sorry, amibiguous username (more than one match) - jos
<trackbot> Try using a different identifier, such as family name or username (eg. jdebruij2, jderoo)
<sandro> it's josb
<ChrisW> ACTION: josb to correct safeness definition (wrt mapping for variables) [recorded in http://www.w3.org/2009/02/03-rif-minutes.html#action02]
<trackbot> Created ACTION-702 - Correct safeness definition (wrt mapping for variables) [on Jos de Bruijn - due 2009-02-10].
cmsa: you wanted termination if forward chaining
<josb> only for a very naive implementation
Axel: yes, otherwise it will not terminate
csma: check termination outside of the rule system
<Harold> We are taking about 'pure' production rules -- otherwise the 'halt' statement could be used.
<sandro> I think we're talking about static analysis of rulesets to see if they are guaranteed to terminate.
Axel: know a Datalog system which
has forward chaining
... and would not terminate
csma: general problem of "forward
Dave: too me it is a problem with a rule set
<AxelPolleres> If it is a problem with the ruleset, then it shouldn't be core.
<sandro> DaveReynolds: The question is whether you ALLOW people to write non-terminating rulesets.
Dave: issue of the conformance clause
<sandro> axel: the whole idea of safeness was to guarantee termination
Axel: idea of safeness condition was to guarantee that calculation terminates and produces results
csma: if rule set implies infite model I don't see a problem from the conformance point of view
Axel: these systems are very simple - do naive grounding and forward reasoning
<josb> should we really care about such naive implementations?
<sandro> no, that's not it.
cmsa: your concern is that Core rule sets in these engines will lead to non termination
csma: do we have a test case?
<Zakim> sandro, you wanted to ask if there are systems which will reject rulesets which terminate, but don't pass the syntax tests which guarantee termination
<DaveReynolds> http://www.w3.org/2005/rules/wiki/Chaining_strategy_numeric-add_1 is that an example?
Sandro: the Axel's system will reject the rule set by a syntactic test?
<sandro> axel: the checking could be turned off.
<AxelPolleres> a(Y) :- a(X), func:numeric-add(X,1) = Y.
<AxelPolleres> a(Y) :- a(X), func:numeric-add(X,1) = Y.a(Y) :- a(X), func:numeric-add(X,1) = Y.
<AxelPolleres> b(Y) :- a(X), func:numeric-add(X,1) = Y.
Axel: this rule would be fine - without recursion
csma: issue of finiteness is that there are some rule engine which will reject unfinite Core rule sets
<sandro> it's about what to do with "Potentially Non-Terminating Rulesets"
<josb> Sandro, it's the program that does not terminate, not the ruleset
Axel: even if a syntactic check will be switched of the rule engine will simply not terminate
<cke> The rule is not safe because variable X is not bound. right?
<sandro> sure, Jos, I'm simplifying a little.
Axel: all ASP engine would not accept this kind of rule set
<sandro> (Answer Set Programming)
<Harold> Dave mentioned a recursion test earlier. Here we could have (except we would need to choose a MAXINT): a(Y) :- a(X), pred:numeric-less-or-eq(X,MAXINT), func:numeric-add(X,1) = Y
Axel: they do some forward chaining checks
<DaveReynolds> Can we require conformance only over rulesets with finite models?
<sandro> I don't think that helps, Dave.
csma: could be handeled by
... as Dave suggested
sandro: problem is that the systems can only do syntactic check
<AxelPolleres> The system which excepts non-recursive use of fuilt-in predicates is already an advanced one.
Dave: not sure if we can have a definition for all the different systems
<AxelPolleres> examples for important rulesets?
csma: we are back to discussion of conformance clauses of Core
Sandro: we need more data
<josb> I think I managed to technically fix the definition: http://www.w3.org/2005/rules/wiki/Core#Safeness
<sandro> Sandro: How important are little-core (finite core) and big-core (infinite core) in the world, and can we drop one of them.... Need more data.
<josb> I still have to improve the presentation, though
<ChrisW> ACTION: axel to investigate implementations that will reject infinite rulesets [recorded in http://www.w3.org/2009/02/03-rif-minutes.html#action03]
<trackbot> Created ACTION-703 - Investigate implementations that will reject infinite rulesets [on Axel Polleres - due 2009-02-10].
<Harold> Can we have MAXINT, MAXDOUBLE, MAXFLOAT, and the other few ones that can prevent that we run into infinite models in the absence of function symbols?
<AxelPolleres> I would really like to see the important examples, indeed.
<LeoraMorgenstern> I will try to think of some, but I don't want to take an action to do this.
Garry; business rules typically use rule fire limit (meta data)
<AxelPolleres> A *practical* ruleset that isn't guaranteed to terminate, please.
<sandro> ie one that falls back on the halting problem, instead of the easier syntactic checks.
Jos: Axel needs to specify the restrictions when a rule set does not terminate
<sandro> axel: "strong safeness" based on the dependency graph of the ruleset
<LeoraMorgenstern> Sandro, are you thinking of some complicated double recursion, that would not be obvious syntactically?
<Harold> Of course we are fine that things like p(1) :- p(2), p(2) :- p(1) won't terminate.
<sandro> well, that will terminate, Harold, with anything but a completely-naive forward chainer.
<trackbot> ISSUE-80 -- Shoudl we extend DTB to include more general builtins -- OPEN
Axel: removed all type specific
... they are redundant due to new predicates
<Harold> No, Sandro, "things like this" are not decidable in the general case.
Axel: equality issue: equal and non equal datatype for all numeric datatypes
<AxelPolleres> with the following semantics:
<AxelPolleres> literal-equal is true if and only if arguments equal and in the
<AxelPolleres> valuespace of any of the supported datatypes, false otherwise.
<AxelPolleres> literal-not-equal is true if and only if arguments are in the
Axel: replace equal with non-equal predicates
<AxelPolleres> valuespace of any of the supported datatypes and unequal, false otherwise?
csma: equal / not-equal should also work with datatype with disjoint value spaces?
Axel: covered by this definition
<sandro> Harold, one of the control strategies I'm used to is that you stop firing rules when no new facts are inferred. That'll handle your case, right?
Axel: no casting in this definition
csma: but for numeric datatype?
ChrisW: replacing type specific equality predicates with one that takes it as an argument?
Axel: not aware of this
... we still would need to take care that the variables are bound
<AxelPolleres> # 184.108.40.206 pred:numeric-equal (adapted from op:numeric-equal)
<AxelPolleres> # 220.127.116.11 pred:numeric-not-equal
<AxelPolleres> * xs:double
<AxelPolleres> * xs:integer
<AxelPolleres> * xs:decimal
<AxelPolleres> # 18.104.22.168 pred:string-equal
<AxelPolleres> # 22.214.171.124 pred:string-not-equal
<AxelPolleres> * xs:string
<AxelPolleres> # 126.96.36.199 pred:dateTime-equal (adapted from op:dateTime-equal)
<AxelPolleres> # 188.8.131.52 pred:dateTime-not-equal
<AxelPolleres> * xs:dateTime
<AxelPolleres> # 184.108.40.206 pred:date-equal (adapted from op:date-equal)
<AxelPolleres> # 220.127.116.11 pred:date-not-equal
<AxelPolleres> * xs:date
<AxelPolleres> # 18.104.22.168 pred:time-equal (adapted from op:time-equal)
<AxelPolleres> # 22.214.171.124 pred:time-not-equal
<AxelPolleres> * xs:time
<AxelPolleres> # 126.96.36.199 pred:duration-equal (adapted from op:duration-equal)
<AxelPolleres> # 188.8.131.52 pred:duration-not-equal
<AxelPolleres> * xs:dayTimeDuration
<AxelPolleres> * xs:yearMonthDuration
<AxelPolleres> * 3.6.1 pred:XMLLiteral-equal
<AxelPolleres> * 3.6.2 pred:XMLLiteral-not-equal
<AxelPolleres> * rdf:XMLLiteral
<AxelPolleres> # 184.108.40.206 pred:text-equalD
<AxelPolleres> # 220.127.116.11 pred:text-not-equal
csma: difference between string and text
Axel: rdf:text and string
csma: 10 as integer and 10 as decimal - do they refer to numeric-equal
Jos: on F2F in Paris we had a decision to have this predicates?
csma: generic equality / unequality would automatically support the RIF datatypes
<Harold> Sandro, for Core we should have termination both under forward and backward reasoning.
<AxelPolleres> guess we can't close that now
continue next time
<sandro> Harold, practical termination yes, but guaranteed termination for all rulesets that can be written? That might be too restrictive.
<cke> I agree with "for Core we should have termination both under forward and backward reasoning", if we ever have termination concept
<ChrisW> ACTION: axel to add the generic equality predicates to DTB for discussion (editors note this is still under discussion) [recorded in http://www.w3.org/2009/02/03-rif-minutes.html#action04]
<trackbot> Created ACTION-704 - Add the generic equality predicates to DTB for discussion (editors note this is still under discussion) [on Axel Polleres - due 2009-02-10].
<AxelPolleres> jos, rationale is: to make things simpler, I know that this would contradict the paris decision.
<AxelPolleres> anyways, I am not religious about dropping the type specific eaualities.
<AxelPolleres> ... just fulfilled the action to look into that. ;-)
<ChrisW> Michael_Kifer, were you on the call?
<ChrisW> As of this point the attendees have been Attendees: Christian, ChrisW, Changhai, Jos, Leora, Harold, Adrian, Gary, DaveR, Stella, Sandro, Axel
This is scribe.perl Revision: 1.133 of Date: 2008/01/18 18:48:51 Check for newer version at http://dev.w3.org/cvsweb/~checkout~/2002/scribe/ Guessing input format: RRSAgent_Text_Format (score 1.00) Succeeded: s/rules/rulesets/ Succeeded: s/that can lead /that can prevent that we run in/ Found Scribe: Adrian Paschke Found ScribeNick: AdrianP Found Scribe: Adrian Paschke Found Scribe: AdrianP Inferring ScribeNick: AdrianP Scribes: Adrian Paschke, AdrianP Default Present: (none) Present: Christian ChrisW Changhai Jos Leora Harold Adrian Gary DaveR Stella Sandro Axel Regrets: PaulVincent HassanAit-Kaci Agenda: http://lists.w3.org/Archives/Public/public-rif-wg/2009Feb/0009.html Got date from IRC log name: 03 Feb 2009 Guessing minutes URL: http://www.w3.org/2009/02/03-rif-minutes.html People with action items: axel jos josb WARNING: Input appears to use implicit continuation lines. You may need the "-implicitContinuations" option.[End of scribe.perl diagnostic output]