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Re: [RIFRAF] ho to proceed? Part 2: open points on discriminators to be added

From: Axel Polleres <axel.polleres@urjc.es>
Date: Tue, 23 Jan 2007 01:43:03 +0100
Message-ID: <45B55A17.80707@urjc.es>
To: W3C RIF WG <public-rif-wg@w3.org>

> 2) Second, I try to summarize open  points on discriminators with the 
> question whether these are still important, etc.

Here the mostly unanswered issues I found in the actions and mailinglist
(there was actually not much traffic on RIFRAF recently) on the
discriminators in the questionnaire:

Especially, I would ask Paula, Alex, Paul, Frank, Hassan and Harold to
comment the following points where appropriate, in case we decide to
step back to the questionnaire or how we can get all this into the ontology:

1) Axel: Get negation into the questionnaire and Ontologization of

This is still open, admittedly.

I'd basically suggest the following discriminators:

  1. Body literals allow negation as failure

  If yes:
     1. Body literals only allow stratified negation as failure

     If no:
        1. Body literals allow well-founded negation as failure
        1. Body literals allow stable negation as failure

  1. Body/head literals allow classical negation

  1. Body/head literals allow strong negation

  For definitions of strong/classical and negation a failure, see

  This proposal addresses ACTION 177 which should be reformulated upon
  what the group decides.

2) Paula suggests:

please see my comments inline:

(New discriminator to be added to 5.1)
What kind of rules are used for realizing the reactive behaviour?
  * Event-Condition-Action (ECA) rules
  * Event-Condition-Action-Postcondition (ECAP) rules
  * Production rules

[Axel] Can we add the acronym  "(CA)" here, to keep the same notation,
or what else did you mean with Production rules ?

  * Other (Please specify!)

(Update of discriminator 5.1.2; add the possibility to answer with
'Mixed' to the question)
Are the different parts of a rule (e.g. Event, Condition, Action parts
for a ECA rule) clearly separated (separation of concerns)?
  * Yes
  * No
  * Mixed (some rules in the language follow such a separation of
concerns, some not)

The comments to the question 5.2.3 'Does the language support only
atomic events or also composite events (combinations of more than one
event such as temporal or events)?' could be considered as basis for a
new discriminator for the (concrete) types of composite events
supported. The problem is that there are two many possibilities for such
concrete composite events supported by a reactive language. Moreover,
the questionnaire already contains similar discriminators but more
abstract (see 5.2.6 and 5.2.7). Thus, I propose not to add a new
discriminator for types of composite events.


[Axel] I propose to follow these suggestions.
  As for one, we could even go into more detail
adding subdiscriminators on the allowed events, conditions and actions.

3) Alex:
Suggests distinction: "active vs passive rules"

[Axel]: I think this is covered by ECA vs CA rules, isn't it?

"global (non-contextual) and local (contextual) rules"

hmm, not sure how I could put this in a discriminator? Do you have a

4) Paul:

"Business Events rule language ~= PRR + event semantics
many ECA rules may be considered derivatives / specializations of
production rules
Note there are no CEP use cases."

[Axel]: No additional discriminators seem to be imposed by this analysis
either, but this seems to suggest new use cases.

5) Frank, Hassan made several proposals long time ago  for type
discriminators, not taken into accountor decided upon yet:


[Axel]: How to proceed with these?

6) Harold suggests to add:

Positional vs. slotted arguments
(already in RIFRAF):

Positional arguments: f(A1, ..., An)

Slotted arguments: f{k1->A1, ..., kn->An}

Remark: f(A1, ..., An) viewable as shorthand for f{1->A1, ..., n->An}

[Axel: No objection to add this in principle.]

Dr. Axel Polleres
email: axel@polleres.net  url: http://www.polleres.net/
Received on Tuesday, 23 January 2007 00:43:11 GMT

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