Re: [RIF] New diagram with Goals, CSFs, and Requirements

Thank you for your comments!

Some explanations can be found inline.

Paula

Dave Reynolds wrote:
>
> [new DC diagram]
>
> I mostly like it.
>
> Significant comments:
>
> o As already stated I would prefer the third goal to be "Basis for a 
> future semantic web rules language". This would imply support for 
> requirements such as: 
> http://www.w3.org/2005/rules/wg/wiki/Standard_RIF_must_be_able_to_expres_RDF_deduction_rules 
> which are not currently included.
>
First, the third stated goal, 'W3C Consistency', is more general than 
your proposed goal and it expresses excatly what we need for RIF. 
Second, I don't think that our goal in this WG is to develop a basis for 
a future Semantic Web rule language, but to enable interchange between 
existing  and future (Semantic) Web rule languages (this is different in 
my opinion).

The text below the diagram is not complete yet; that is why the support 
of RDF deduction rules is missing, but this comes actually under 
'Support RDF'. We kept the titles of the requirements as short as 
possible and their explanations will come soon.
> o 1.1.c Meta language features. I'm unsure about this on several levels.
> First, why does this appear under "no surprises"? To me it seems only 
> related to coverage. Second, priorities seem like a different issue 
> from meta-level rules, perhaps they should be separated. Third, I'm 
> not convinced that general metalevel rules really fall above the cut 
> line for us before phase 3. Fourth there needs to be "opposes" links 
> from this to at least "low cost of implementation"; doesn't this also 
> make ruleset combination hard?
>
Regarding your first comment: Take as an example a set of rules where 
priorities are used; if through interchange this information is lost 
then you get a kind of surprise in the sense that 'unexpected' results 
might be obtained.

Regarding your second comment: You're right, they are different...but at 
the same time one can consider that they express some meta-level 
features; so, for keeping the diagram as simple as possible we consider 
them falling in the same category.

To your third comment: the proposed DC diagram and the whole work we 
have done on goals, CSFs, and requirements do  not take the different 
RIF Phases into consideration.

To your fourth comment: You're right, I think some 'opposes' links are 
missing.
> o I don't understand the phrasing of 1.1.a Formal Semantics. The text 
> seems to be about multiplicity of semantics in which case there needs 
> to be a separate requirement that RIF Core should have a (i.e. at 
> least one) formal semantics. The phrasing is unclear on whether this 
> is addressing RIF Core or the sum of RIF dialects, if the proposal is 
> that the Core should itself not be "unitary" then that needs to spelt 
> out more clearly so we can argue about it.
> [Actually, difference between RIF Core and RIF dialects us unclear at 
> several places in the text.]
As mentioned above, the DC proposal does not differentiate between 
different RIF phases or RIF core and dialects. I think it is best 
leaving this separation for future work, say after taking a decision on 
the overall DCs. So, the requirement states the need for multiple 
semantics for RIF but gives no information on which RIF is meant here. 
However, I agree that the text needs refinement and I'll do that 
together with Frank in the next days.
>
> o Markup of semantics. I guess I still don't understand what people 
> mean by this phrase. Is this supposed to be:
> (a) machine processable definition of the semantics in some general 
> formalism like an operational semantics?
> (b) metadata tags attached to symbols to distinguish divergent use of 
> apparently similar symbols (e.g. ->)?
> (c) different symbols for constructs with different semantics so that 
> each symbol is unambiguous?
> (d) any and all of the above?
>
In my opinion, markup of semantics does not refer to the items listed 
above. This requirement states that there is a means to specify the 
formal semantics of a rule set to be interchanged so that the system 
using this rule set through RIF knows about its formal semantics; this 
does not mean that the algorithm for evaluating the rule set comes with 
the interchanged rules. It might well be just a URI where the 
specification of the rule set's formal semantics is given. Also, such a 
formal semantics is to be attached only to rule sets.
> Lesser comments:
>
> o Why is "Support XML" linked to "Extensibility"? That doesn't seem 
> intuitive to me and I couldn't spot the explanation in the narrative.
I think Frank can explain best this link :)
>
> o Conformance model. I've not yet seen an example of when a default 
> behaviour other than "ignore ruleset" could be used and question the 
> linking of conformance model to the "default behaviour" proposal 
> (which currently only has one named champion).
The conformance model is more general than just 'ignore ruleset'. It 
also relates to the multiple formal semantics for different rule sets, 
e.g. in case one needs to combine two rule sets with different 
semantics. There are also other examples such as interchange between 
systems supporting priorities for rules and systems without such support 
where other conformance models than just ignore rules could make sense.
>
> Dave
>
>
>