RE: [PRD] PRD TF telecon Tuesday 14 October


I will not be able to attend today's PRD task force's telecon - so I am
sending my regrets (since there is no page for PRD TF Telecon Regrets).

Here is my take on the frame and aggregates issues as they are related):

(1) Frames as they are defined and given semantics is BLD are useless for
    most OO models such as those used in Production Systems where objects
    have variable (field) arity and each field is mono-valued (BLD's frames
    have multi-valued fields). The designers of BLD (MK & HB) have defined
    a collection semantics based on aggregating mulitple values of a frame's
    fields using a set constructor. This is problematic as this introduces
    a confusion when a field's value is already a set.

    A safe, simple, and more general way that would solve this problem is
    not to build the set-collection semantics into BLD's semantics of frames
    with multiple field values, but rather to parametrize BLD's semantics
    with a monoid collector (that can be set, bag, list, +, *, max, ...)
    that is used to bundle and unbundle frame field values. In this way,
    all we have to do when exchanging BLD -> PRD or PRD -> BLD, the (normative)
    RIF XML format, is to specifiy a monoid collector per field (which could
    default to set if left unspecified). Then, all that needs to be done is
    to bundle/unbundle objects represented as frames, is declare what monoid
    (if any) is associated to a frame's field. This is simple to specify in
    the RIF XML format that we are defining to be normative.

(1) A simple and formal semantics of aggregates suitable for PRD (and IMHO
    for BLD as well) and which is all we need to accommodate all sorts of
    aggregations as well as to deal with multiple-valued field frames, is
    described in the attached article whose reference is (which I have
    mentioned already several times to this WG):

             author = {Leonidas Fegaras and David Maier},
             title = {Optimizing object queries using an effective calculus},
             journal = {ACM Trans. Database Syst.},
             volume = {25},
             number = {4},
             year = {2000},
             pages = {457--516},
             publisher = {ACM},
             address = {New York, NY, USA},

    I urge all would-be formal semanticists to *READ* this paper before trying
    to reinvent the (square) wheel. It is a very important paper in that it gives
    a simple, elegant, and effective formal operational semantics of all possible
    sorts of aggregates.

Hassan At-Kaci  *  ILOG, Inc. - Product Division R&D

-----Original Message-----
From: on behalf of Christian de Sainte Marie
Sent: Mon 10/13/2008 6:42 PM
Subject: [PRD] PRD TF telecon Tuesday 14 October

Teleconference W3C RIF WG
Production rules dialect (PRD) task force
14 October 2008

North America and Europe are in the summer time:
1700 UTC, 1000 (West US) 1300 (East US) 1800 (London) 1900 (Paris)

Duration: *60 min*
*Proposed agenda*
1. Follow-up on the discussion about Frames VS Objects at the RIF telecon (15 mn)
2. Actions in PRD (30 mn)
- Continued from last week [1]; see also Changhai's email and following thread [2]
3. Principles, scope and priorities (PRD wrt BLD, XML vs PS, prioritizing issues, timeline) (15 mn)
4. AOB
- Next meeting


*Telecon details*
Zakim bridges: +1.617.761.6200 (US), +33 4 89 06 34 99 (F) or +44.117.370.6152
Conference code: 743773 ("RIFPRD")
IRC Chat: (port 6665), #rif-prd
Web-based IRC (member-only): []

Please note that RIF-PRD telecons are for attendance only by RIF Working
Group Participants and guests invited by the chairs. conference

Received on Tuesday, 14 October 2008 13:59:50 UTC