See also: IRC log
<ChrisW> Meeting: RIF Telecon 1 May 2007
<sandro> can you hear me at all now?
<Harold> Zakim [NRCC] is me.
<ChrisW> scribenick: DavidHirtle
<ChrisW> Scribe: David Hirtle
<PaulVincent> Thanks Dave! I so enjoy my little chats with Zakim...
chris: anyone who hasn't filled out the survey for the F2F, please do so
<PaulVincent> Unless dinner is ++ better than the meeting...
chris: 22 people who will attend the meeting, and 28 who will attend the dinner...
sandro: make your hotel reservations soon if you haven't already
<PaulVincent> NO update from PRR
<ChrisW> POWDER working group
chris: POWDER is another SemWeb WG working on content rating...
<AxelPolleres> interesting, that fits with one of our use cases.
chris: they've identified some
rules use cases and want some feedback from us
... I'll forward to our list; feel free to reply
<sandro> Axel: I sent comments on SPARQL that could perhaps been endorsed by RIF. For now I just sent them as myself.
<sandro> Chris: Alas, we didn't have time to make that formally from RIF.
<sandro> Chris: I think it's fine.
chris: main discussion in the group is between ONDS and OS choices
<sandro> Sandro: translation to DS is hard, from DS is easy.
<sandro> Chris: Straw Poll. Who likes OS?
<AxelPolleres> Can MK comment on that?
<sandro> Chris: translations from lower numbers to higher numbers is easy; not the other way around.
chris: translating from a higher number choice back to lower number (esp 3 to 1) is hard
hassan: why is it difficult to translate from higher number to lower?
<AxelPolleres> That was a question.
<DaveReynolds> Actually #2 (ONDS) to #3 (OS) is not quite trivial if you have equality
<AxelPolleres> what hassan mentions is 2 -> 1, that is easy.
<DaveReynolds> agreed 1 <-> 2 is trivial, it is 3 (OS) which makes it hard, both ways
chris: there are some entailments that make it extremely difficult from 3 down to 1 (or even 2)
hassan: if you interpret it then it has a unique meaning; you can spew it out unambiguously
michael: hassan is right, translations in both directions are possible
<sandro> p(a), q(b), p=q, in OS entails p(b) and q(a), right.
<sandro> ChrisW, I'd be interested to hear the results of the straw poll, but I'd like to know if folks can vote for more than one option.
<Hassan> OSR is even better IMHO
chris: michael, from OS into DS is easy?
michael: depends on what you mean by easy; can use a predicate etc.
<sandro> MichaelKifer: it was proven in the HiLog paper ...
<sandro> Chris: a predicate for each arity ... a combinatoric explosion of rules.
hassan: where's the combinatorial explosion come from?
<sandro> Hassan: please explain combinatoric explosion
michael: number of rules
<sandro> MichaelKifer: grown in the size of each rule, but the same number of rules, same number of symbols. I think the grown is actually linear.
sandro: if no one is going to argue other side, no need for argument
chris: yes, vote for more than
one if you're happy with that
... or we'll just ask who is against
... who's opposed to choice 3 (OS)?
<sandro> (say "-1 OS" if you are opposed.)
<sandro> (no one opposed)
chris: anyone opposed to 2 (ONDS)?
<sandro> -1 ONDS
<MichaelKifer> -1 onds
<DaveReynolds> preference against ONDS but not rule it out
hassan: I'm opposed to it
<sandro> -1 DS
chris: who's opposed to DS?
<AxelPolleres> -1 DS
<Hassan> hak -1
<MichaelKifer> -1 ds
<sandro> Allen: -1 DS
chris: so no one's opposed to 3; sounds like consensus
sandro: hassan seems to prefer 4, but we don't need to choose now: can just add reflection later
hassan: better to have reflection from the start, especially if it's not too costly to add
chris: is there an encoding of a reflective rule (rule that takes the syntax of the language and puts it into the language)?
michael: I don't know; haven't discussed it
sandro: by picking 3, we're not ruling out 4
michael: we need to pick up one and define semantics accordingly
sandro: have you thought about semantics of 3 vs 4?
michael: I know how to do semantics for 3 etc. but there are options for 4 (even syntactic)... we cannot just leave it open
chris: I agree with that; we should agree on 3 or 4
<sandro> Hassan: Reflection is the possibility to describe your abstract syntax in your semantics.
<sandro> MichaelKifer: How much introspection do you want to allow?
<Harold> Pat Hayes recently put forward the very
<Harold> general IKL system
<Harold> which may be of interest here
<Harold> regarding syntactic self-description:
sandro: let's resolve on 3 or 4 for now and discuss it more next week
<sandro> MichaelKifer: introspection for encoding rules as data isn't a problem, but if we get close to Liar Paradox, etc, then it's another matter.
michael: I'm concerned about what happens when we go into a first order dialect
<sandro> MichaelKifer: so it's easy enough to have some quotation, but if we get extended to FOL it may cause problems.
<Harold> How much would we go in the direction of KIF and CG if we introduce quotation mechanism?
michael: a first order extension of this could lead to paradoxes, e.g. whatever I'm saying is a lie
hassan: a very simple reflection mechanism can't harm you
michael: I don't know what the consequences are going to be if we allow reflection in the core; in a dialect only, it's not a problem
hassan: if you're designing a
language, having the possibility to describe your own syntax is
... I don't see any dire consequences
michael: in FOL, if you allow self-reference, you have to be very careful
<Harold> Could we have a 1st-order-capable Core and a (Reflective) Extension Layer above it, of possible use for some Dialects.
chris: everyone seems to be
talking about a different aspect of reflection
... hassan, could you write up a proposal about reflection you have in mind?
hassan: sure, but I'm just using general programming language notion
<sandro> hassan: I'm talking about something like Prolog's "univ" ( written "=.." ).
<sandro> Chris: My concern is whether there is a way to support that in things like FOL.
hassan: a language that does not support reflection doesn't have to worry about it
<sandro> Chris: We're trying to make the the Core be something that can be translated to every other languages.
chris: yes, it does, in order to be compliant
sandro: concrete example: we have a ruleset and we're translating it to FOL ... if the rule is trying to infer new data, does it affect rules themselves?
chris: anyone else in favor of adding reflection to Core?
chris: hassan, please send a
message to the list and we'll discuss next week
... if no other support, we'll have to move to a dialect
sandro: let's resolve that we agreed on 3 or 4, not 1 or 2
hassan: I won't object to 3; I won't be able to attend next week
<PaulVincent> I'd be interested in reading Hassan's arguments for 4...
michael: I won't be on the telecon next week either
<sandro> PROPOSED: To go with 3 or 4, and next week we'll decide between 3 and 4, if Hassan's e-mail convinced anyone.
<sandro> PROPOSED: To go with 3 (OS) or 4 (OSR), and next week we'll decide between 3 and 4, if Hassan's e-mail convinced anyone.
chris: any objections?
<sandro> RESOLVED: To go with 3 (OS) or 4 (OSR), and next week we'll decide between 3 and 4, if Hassan's e-mail convinced anyone. (cf http://www.w3.org/2005/rules/wg/wiki/Issue-31)
chris: I'm not really prepared on this issue; christian not here
sandro: I feel somewhat
... DaveR may be more than me if he'd rather
DaveR: I took issue to be that we have requirement about attaching metadata to rules... how do we represent, what are core items, etc?
<sandro> DaveReynolds: How do we represent Metadata? What core vocab should we have? And How extensible should it be?
<sandro> DaveReynolds: I think it should be, in the style of RDF, completely open ended.
<sandro> Sandro: what if you use RDF in RIF Core format?
<Hassan> BTW: having meta-data is having some relection
<sandro> Chris: So what if you have a rule like "All the rules authored by Chris are false" ?
chris: we have to be careful about putting this in core because of problems in translating rules into languages that don't support it
<sandro> Sandro: How about having a file have a Ruleset and a Metadata set, and you can merge them at your own risk.
chris: one obvious way to express
RDF as metadata would be to use triples
... what metadata do we need?
<sandro> 4.1.5. Embedded metadata
<sandro> RIF must support metadata such as author and rule name.
<Harold> A 'rulename' can be used to *attach* metadata to rules such as 'author'.
<PaulVincent> Rule metadata - see Dublin Core; properties like priority etc
<sandro> Chris: just wondering about kinds of metadata that might impact the core.....
<sandro> DaveReynolds: date, provenance,
chris: is Dublin Core enough?
<sandro> DaveReynolds: for round-tripping, we might need "the original form of name"
Paul: usually in rule-matching systems, data defined for customer
<DaveReynolds> +1 to Chris, translator hint annotations seem valuable
Paul: obvious one is original language in which rules are defined, also source rules as comments
chris: we have this Dublin Core metadata, round-trip "preservation metadata", any other kinds?
allen: dialect identification metadata?
sandro: I don't think that's metadata
Harold: instead of giving dialect as metadata, could have different URLs pointing to different XML Schemas of RIF
<DaveReynolds> Harold - surely a URL refernce is just a form of metadata?
<PaulVincent> Reference: http://dublincore.org/
sandro: I agree, could have different namespace for each dialect
harold: XSD is quite weak; may involve other things like Schematron or even semantic validators (for results of static analysis)
<Harold> Dave, I meant the URL that points to the definition of a dialect such as to its xml schema.
chris: does each dialect define set of metadata fields?
<Harold> Chris, about the direction of pointing between a RIF file and its metadata, I think essential metadata (about results of static analysis) cannot point from outside into their RIF file -- they must be attached to the ruleset iteself.
chris: where do we stand?
allen: need to add text for figures, otherwise nothing else
chris: should we have a use cases section at F2F?
allen: phase 2 requirements...
chris: I think Paula started a list of phase 2 requirements
allen: I did the ontology thing using imports and sent it to the list a while ago... just wanted to make sure it's okay
<AxelPolleres> Suggestion: Can we postpone this discussion until in two weeks (will be)
<AxelPolleres> travelling next telecon!
chris: so schedule F2F time to talk about RIFRAF
<AxelPolleres> sorry, cannot unmute, my skype is somewhat stuck
<AxelPolleres> please schedule rifraf on day 1 (june 2)
<ChrisW> Chair: Chris Welty
<ChrisW> Chair: Chris Welty
This is scribe.perl Revision: 1.128 of Date: 2007/02/23 21:38:13 Check for newer version at http://dev.w3.org/cvsweb/~checkout~/2002/scribe/ Guessing input format: RRSAgent_Text_Format (score 1.00) Succeeded: s/any c/any dire c/ Succeeded: s/n?/n to Core?/ Succeeded: s/Schematron/Schematron or even semantic validators (for results of static analysis)/ Found ScribeNick: DavidHirtle Found Scribe: David Hirtle Default Present: Sandro, ChrisW, Mike_Dean, Dave_Reynolds, PaulaP, DavidHirtle, Harold, AxelPolleres, PaulVincent, Hassan_Ait-Kaci, Allen_Ginsberg, IgorMozetic, +39.047.101.aaaa, MichaelKifer, +1.403.762.aabb Present: Sandro ChrisW Mike_Dean Dave_Reynolds PaulaP DavidHirtle Harold AxelPolleres PaulVincent Hassan_Ait-Kaci Allen_Ginsberg IgorMozetic +39.047.101.aaaa MichaelKifer +1.403.762.aabb Regrets: FrançoisBry JosDeBruijn MichaelSintek MarkusKrötzsch DeborahNichols Agenda: http://lists.w3.org/Archives/Public/public-rif-wg/2007May/0011.html Got date from IRC log name: 8 May 2007 Guessing minutes URL: http://www.w3.org/2007/05/08-rif-minutes.html People with action items:[End of scribe.perl diagnostic output]