RIF Telecon -- 15 Jan 2008

<ChrisW> Meeting: RIF Telecon 15 Jan 2008

<ChrisW> Scribe: Gary Hallmark

admin

<ChrisW> EtnaRosso, who are you?

<EtnaRosso> hi ChrisW

<EtnaRosso> should i go? i'm not involved in rif

<ChrisW> yes

<EtnaRosso> ok have a good meeting

<ChrisW> bye

<scribe> Scribe: Gary Hallmark

<scribe> ScribeNick: GaryHallmark

<ChrisW> anyone on IRC who is not on the phone???

<PaulaP> I am not on the phone yet

<ChrisW> http://lists.w3.org/Archives/Public/public-rif-wg/2008Jan/att-0028/rif-minutes-jan8-2008.html

<ChrisW> Minutes of Jan 8 Telecon

<ChrisW> RESOLVED: Accept Jan 8 Telecon minutes

Liason

<AxelPolleres> test

<csma> @Axel, Zakim is not with us, that's why...

<csma> ...he got to excited and had to leave...

josb: owl DL and owl Full have incompatible RIF mappings

<Harold> Did the OWL WG look into the RIF builtin proposal?

<csma> ack ??P29

harold: RIF uses functions as operators, what does owl do?

josb: mathML is being discussed, more on Friday

<ChrisW> ack ??

<Harold> 41#

Issue 47

<csma> PROPOSED: to close issue 47 without action (i.e. equality stays in BLD as it is currently specified)

chrisw: last week, nobody objected

<DaveReynolds> I'll abstain

<Hassan> me

<csma> RESOLVED: to close issue 47 without action (i.e. equality stays in BLD as it is currently specified)

<ChrisW> Abstentions: Hassan (Ilog), DaveR (HP)

Issue-44

<ChrisW> ack ??

harold: relational tables map naturally to slotted uniterms

csma: could just agree on position out of band
... in slotted case, need to agree on table and column names anyway

harold: such a "schema" of DB is needed, but is a different issue

csma: do not need slotted uniterms to avoid OIDs

harold: slot names are self-descriptive
... if frames need slots, why not uniterms?
... slotted uniterms implemented in ojdrew

sandro: any relation of frames to bnodes?

josb: skolemize blank nodes
... but embedding relations is different from RDF

sandro: embedding relational DB in RDF is common
... should be able to use frames for RDF and relational data

mark: need anonymous or local OID

csma: RIF does not specify an OID format

mark: rule engines don't generate the OID until fact is inserted into engine

<AxelPolleres> Is that relating to set- vs multiset-semantics? i.e. two uniterms with different generated oids are different things (objects), but not if you just see the uniterm... our logical semantics is obviously set-based

<AxelPolleres> jos, I think the discussion is whether we need slotted uniterms, or whether they can (in *any* case) be emulated with oids?

josb: tuple is self-identifying -- doesn't matter if you use names or positions
... reiterates csma's point

harold: Codd's intent of "tuple" seems to include slots

<josb> columns, not rows!!!!

<josb> not frames, uniterms!!!

chrisw: does converting to frames do anything bad?

axel: tuples can appear > 1 (multiset)

josb: pure relational is set based, SQL is multiset

axel: need OIDs anyway to handle duplicate tuples

harold: what about positional frames?

<AxelPolleres> +1 to what you said now, harold. I didn't speak againt named uniterms.

harold: slots and OIDs are independent, so 4 combinations

<AxelPolleres> ... only against the use case relational databases. Agree, that this is ugly in RDBMS

csma: RIF not meant to interchange DBs

harold: but we are close to datalog and should be useful for such interchange

chrisw: straw poll

<Harold> Gary: yes.

<ChrisW> Who favors keeping named-argument uniterms?

-1

<Harold> +1

<Hassan> 0

<josb> -1

<IgorMozetic> +1

<PaulaP> 0

<AxelPolleres> +1 for reasons mentioned in the last telecon, I favor keeping BLD general and we have a clean definition of these already

<StellaMitchell> +1

<sandro> +1

<ChrisW> Who favors removing named-argument uniterms?

<josb> +1

<csma> +1

<IgorMozetic> -1

<sandro> 0

<AxelPolleres> -1

<DaveReynolds> +1

<Hassan> 0

<PaulaP> 0

<StellaMitchell> 0

<Harold> 0

Builtins

<csma> PROPOSED: BLD WD2 will include the builtins listed in [6] (functions on numerics), [7] (functions on strings) and [8] (functions on dates and times)

<ChrisW> http://lists.w3.org/Archives/Public/public-rif-wg/2008Jan/0073.html

<csma> PROPOSED: BLD WD2 will include the builtins listed in http://lists.w3.org/Archives/Public/public-rif-wg/2008Jan/0073.html

<Hassan> I agree

<PaulaP> this list is for BLD, we didn't discuss this issue for Core

dave: status of builtin functions vs. predicates?

<sandro> Sandro: are external calls excluded from core (as Dave seems to be assuming) ?

dave: don't we need predicates if we don't have equality (talking about Core)
... functions w/o equality makes it hard to return a computed value in an answer

<Harold> Sandro, I dont remember a decision; I think we do need external calls (builtins, fcts or preds) in the Core.

csma: PRD prefers builtin fcns over preds

<PaulaP> we have functions and operators in the list

<sandro> Harold, I agree we want builtins --- I'm just not sure if they might be function-style.

<Harold> Well, only today we decided to keep equality...

<Harold> ... which is needed to call function-style.

<AxelPolleres> add(X,Y,Z) it wouldn't bind a value to Z, but it would have aa fixed interpretation which allows only one value for Z if X and Y are bound.

<AxelPolleres> ... slight difference.

dave: w/o equality in Core, functional style builtins are less useful than predicate style

<Harold> Equality with builtin calls on right-hand side corresponds to Prolog's "is" primitive.

dave: what about list types?
... need to agree on specifics of the list type for next draft
... need to specify collation

<PaulaP> e.g contains

dave: e.g. compare builtin
... minimum is simple codepoint collation
... or just omit colation sensitive builtins altogether

josb: can't decide on list of builtins before deciding on functional vs. predicate style

<csma> Arghhh! The proposed resolution has been implicitely or explicitely on the table for a long long time!

<ChrisW> http://www.w3.org/2005/rules/wg/wiki/List_of_BLD_built-ins

<scribe> ACTION: daver to add collation issue to builtins wiki page [recorded in http://www.w3.org/2008/01/15-rif-minutes.html#action01]

<trackbot-ng> Sorry, couldn't find user - daver

<scribe> ACTION: davereynolds to add collation issue to builtins wiki page [recorded in http://www.w3.org/2008/01/15-rif-minutes.html#action02]

<trackbot-ng> Sorry, couldn't find user - davereynolds

<scribe> ACTION: dreynolds2 to add collation issue to builtins wiki page [recorded in http://www.w3.org/2008/01/15-rif-minutes.html#action03]

<trackbot-ng> Sorry, couldn't find user - dreynolds2

<scribe> ACTION: dreynold2 to add collation issue to builtins wiki page [recorded in http://www.w3.org/2008/01/15-rif-minutes.html#action04]

<trackbot-ng> Created ACTION-400 - Add collation issue to builtins wiki page [on Dave Reynolds - due 2008-01-22].

josb: also need to define semantics of builtins
... before we can evaluate the proposed list of builtins

<AxelPolleres> I think, so far, we only have sketched/discussed the semantics for built-on *predicates*, AFAIK

josb: model theoretic RIF semantics w.r.t. builtins

<csma> ExtTerm

josb: need semantics of "ExtTerm"

<AxelPolleres> We diden't fix how ExtTerms look like though (BTW), did we? We just said we want them to be syntacticcally distinguisheable

chrisw: same semantics as "Term"

josb: but there are outstanding issues w.r.t. Error handling

<Harold> We seem not to know yet if Equality should be allowed both in BLD and in Core, but I think we will need builtins in Core. So in order to allow the more natural functional builtins in Core we should allow (restricted) Equality there.

chrisw: not ready for resolution

Issue 45

chrisw: the issue is about lists

<Harold> http://www.w3.org/2005/rules/wg/wiki/Core/List_Constructor

<AxelPolleres> +1 to jos, nothing to add, we need to have the semantics of built-in preds and functions on the table, then we can discuss it. Agree that it should be straightfwd for most predicates, not sure about functions at the moment, but hopefully similar

<DougL> I think we should have both, don't you think?

<josb> -1 to have both

<AxelPolleres> as for the tagnames, should we use ones more similar to the resp. rdf vocabulary, i.e. List, first, rest, nil instead of Pair

harold: alternatives are pairs vs. n-ary sequences
... n-ary sequences are more common

<DougL> I meant for conceptual impedance matching, allowing both, not saving a few bits. What is the COST of allowing both?

<AxelPolleres> rdf doesn't have seq ... prolog doesn't have seq

chrisw: anyone really want pairs?

<AxelPolleres> they use the pair stuff, but Prolog has syntactic sugar for something which looks like seqs.

<Harold> Axel, prolog has seq's [e1, e2, ..., eN].

<AxelPolleres> I see the point with the blowup in the xml though...

chrisw: pairs take a lot of space to represent in xml

<DougL> These are arguments for allowing sequences; they are not arguments for NOT having pairs as well.

hassan: not completely equivalent in non-ground case

<DougL> that sounds good to me (whoever is saying that)

<DaveReynolds> +1 to Jos

<Hassan> +1 with Jos

<csma> @Doug: it is Jos De Bruijn

<DougL> +2 Jos then

josb: use pairs in language defn, sequences in xml

<DougL> (+2 means: I not only agree, I wish I had said that)

<DaveReynolds> +1

<DougL> +1

<Hassan> +1

<josb> +1

<PaulaP> +1

<Harold> +1

<IgorMozetic> 0

<sandro> +1

<AxelPolleres> 0 why have syntactic sugar in the XML and not in the presentation syntax?

chrisw: straw poll on Jos's statement

<josb> axel: sequences cannot be incomplete, as Hassan mentioned

axel: but language defn should be readable, therefore use sequences

<IgorMozetic> +1 for Axel

axel: don't read xml, don't care about xml syntax

<josb> fine with me as well

<Hassan> fine here too

axel: semantics uses pairs, presentation syntax and xml syntax uses sequences
... prefer 1b for semantics, 1a for syntax

<josb> Seq ( a ?Y c | ?R) as shortcut?

axel: 1a, 1b from http://www.w3.org/2005/rules/wg/wiki/Core/List_Constructor

AOB

chrisw: let's resolve next week

<AxelPolleres> jos? didn't get your example.

harold: which wiki are we supposed to use?

<AxelPolleres> ... what does the pipe there?

<ChrisW> Paula, can you scribe next week?

<josb> we need to distinguish between last element and tail

<josb> after | is the tail (see bottom of page)

<AxelPolleres> I wouldn't allow '|' in Seq

sandro: wants feedback on conversion of docs to new wiki

<PaulaP> bye

<ChrisW> paula

sandro: new wiki can allow wiki editing and html editing

<Hassan> Sorry gotta go... Bye...

<AxelPolleres> but use Seq ( a b c) as a shortcut for rif:list( rif:frst (a) rif:rest( rif:list(rif:irst(b) rif:rest( rif:List( rif:first(c) rif:rest(rif:nil) ) ) )

<ChrisW> d'oh

<ChrisW> d'oh again

- DRAFT -

RIF Telecon

15 Jan 2008

Attendees

Contents