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Re: ISSUE-51: Another possible compromise for metadata syntax --> org vs metadata

From: Michael Kifer <kifer@cs.sunysb.edu>
Date: Mon, 28 Apr 2008 13:25:24 -0400
To: "Paul Vincent" <pvincent@tibco.com>
Cc: "Christian de Sainte Marie" <csma@ilog.fr>, public-rif-wg@w3.org
Message-ID: <11404.1209403524@cs.sunysb.edu>


Paul,
Good observation! But this is already possible with the current proposal.


	--michael  

> Christian - thanks for the diagrams - would be good if you assigned
> ownership to each one so we can relate the discussion vs the model :)
> 
> My 2 cents: metadata and rule organization are SEPARATE concepts. Using
> rule organization to define metadata is unnecessarily restrictive
> (original thought: plain daft, IMHO), and confuses container,
> inheritance and reference relationships.
> 
> Why? 
> 
> Example:
> 
> Group1 has metadata Meta1 which applies (i.e. is inherited by the
> container relationship) to its contents Rule1a and Rule1b. 
> 
> Group2 has metadata Meta2 which applies to its contents Rule2a and
> Rule2b. 
> 
> But Rule1a and Rule2a also share Meta3, and Rule1b and Rule2b share
> Meta4. 
> 
> Solution? Do I create groups Group1a, Group1b as subgroups of Group1,
> and Group2a, Group2b as subgroups of Group2, to handle metadata Meta3
> and Meta4?
> BUT I could equally organize the same rules and metadata with Meta3 and
> Meta3 associated with Group1 and Group2, and subgroups for Meta1 and
> Meta2. Presto: we have another complication in rule interchange.  
> 
> Better solution (IMHO): Any element in RIF can have any number of
> metadata annotations. These are irrelevant (by definition, it seems) to
> rule semantics AND interchange semantics. Rule translators can if
> desired remove such metadata annotations, especially if they have no
> role in the target (e.g. runtime use only). And if you want to share
> metadata across entities, then you define an IRI to a metadata concept
> and specify that common linkage in every element that shares it. [Hmmm
> sounds a bit like an RDF use case...]
> 
> 
> Paul Vincent
> TIBCO | Business Optimization | Business Rules & CEP
>  
> 
> > -----Original Message-----
> > From: public-rif-wg-request@w3.org
> [mailto:public-rif-wg-request@w3.org]
> > On Behalf Of Christian de Sainte Marie
> > Sent: 28 April 2008 14:25
> > To: Chris Welty
> > Cc: Sandro Hawke; Jos de Bruijn; public-rif-wg@w3.org
> > Subject: Re: ISSUE-51: Another possible compromise for metadata syntax
> > 
> > All,
> > 
> > Since I like diagrams, esp. when it comes to compare designs, I tried
> > and translated all these syntaxes into UML-like diagrams (which leads
> me
> > to propose a new solution, in the end).
> > 
> > The rule part of BLD as it was published in WD2 is diagram-1 (I put
> ???
> > when the XML syntax does not give the role a name).
> > 
> > Chris Welty wrote:
> > >
> > > The current BLD draft shows:
> > >
> > >   Document  ::= 'Document' '(' IRIMETA? DIRECTIVE* Group? ')'
> > >   Group     ::= 'Group' IRIMETA? '(' (RULE | Group)* ')'
> > 
> > Shown on diagram 2 (without the DIRECTIVE, which I leave out in all
> the
> > folowwing diagrams as well).
> > 
> > > [ChrisW] suggest[s] something like:
> > >
> > >   Document  ::= 'Document' '(' IRIMETA? DIRECTIVE* (Group | Rule)*
> ')'
> > >   Group     ::= 'Group' IRIMETA? '(' (RULE | Group)* ')'
> > >   Rule      ::= 'Rule' IRIMETA? '(' RULE ')'
> > 
> > Diagram 3. On the diagram, I had to make explicit the abstract class
> > that is common to Group and Rule; I called it ITEM. So, what the
> diagram
> > really show is (I attached the 'meta' association to the abstract ITEM
> > to make for readibility purposes):
> > 
> >    Document ::= 'Document' '(' IRIMETA? DIRECTIVE* ITEM* ')'
> >    ITEM     ::= [ Rule | Group ]
> >    Group    ::= 'Group' IRIMETA? ITEM*
> >    Rule     ::= 'Rule' IRIMETA? '(' RULE ')'
> >    RULE     ::= [ 'Forall' Var+ '(' CLAUSE ')' | CLAUSE ]
> > 
> > > Also, *as a different point*, if we keep this I would suggest
> modifiying
> > > the Group production so that you don't have to type 'Group' for
> every
> > > repeated rule within a group, something like:
> > >
> > >   Group     ::= 'Group' IRIMETA? '(' (RULE* | Group)* ')'
> > 
> > I do not understand this: your initial production allows 0 to many
> RULEs
> > in a Group without having to loop through the Group construct (and,
> > thus, without having to type 'Group' for each new RULE?
> > 
> > However, your proposal raises two questions:
> > 
> > 1. do we really want some implementation to produce a RIF document
> where
> > the RULEs are all 'Forall' or CLAUSE 'sentence's in a 'Group', whereas
> > another implementation, for the same set of rules, would produce a
> > document where the would all be 'Rules' directly 'contain'ed in the
> > Document (e.g. in the case where there are no subgrouping of rules in
> > the original set)?
> > 
> > 2. do we want all facts (heads without a body - was the Talking Heads
> > group about facts, btw?) to have to be labelled 'Rule'? After all,
> that
> > was why CLAUSEs where introduced: to separate rules properly said from
> > facts
> > 
> > One way to avoid both would be to allow Groups to contain ITEMs, not
> > RULEs or other FORMULAs directly (diagram 4):
> > 
> >    Document ::= 'Document' '(' IRIMETA? DIRECTIVE* ITEM* ')'
> >    ITEM     ::= [ Rule | Fact | Group ]
> >    Group    ::= 'Group' IRIMETA? ITEM*
> >    Rule     ::= 'Rule' IRIMETA? '(' RULE ')'
> >    RULE     ::= [ 'Forall' Var+ '(' Implies ')' | Implies ]
> >    Fact     ::= ATOMIC
> > 
> > Wouldn't that last version satisfy everybody? And we can even get rid
> of
> > the CLAUSE production :-)
> > 
> > (NB: if we want to all universally quantified facts, we only need to
> > associate Fact to a new abstract FACT as a formula, instead of ATOMIC
> > directly, where FACT ::= [ 'Forall' Var+ '(' ATOMIC ')' | ATOMIC ])
> > 
> > Cheers,
> > 
> > Christian
> 
> 
> 
Received on Monday, 28 April 2008 17:26:20 GMT

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