All, csma wrote on 18/01/2010 15:43:48: > > 2. in CLIPS, the Modify is, really, a Retract followed by an Assert, > [..] > > That point is not really a problem, as far as regards CR etc, > because this, is, really, what the spec says it does, already. I meant that the spec says that the to-be-modified Frames are removed from the fact base before the modified one is added. Unfortunately, that is not enough: we need the modified frame to be considered a new fact wrt refraction. That means that we need to take into account the transition state after the to-be-modified facts have been removed, and before the modified frame is added. In other words, Modify cannot an atomic action, from the conflict resolution viewpoint :-( Of course, we can specify around that problem, and make Modify atomic from a transactional point of view, but not from a semantical one. That would be rather kludgy, but that is feasible. Another solution is to remove Modify altogether: if it is not atomic wrt the operational semantics, it does not really serve a purpose anymore in PRD (it was already kludgy, anyway, because it is hard to make good sense of Modify for multi-valued slots). >From a design point of view, that seems the right solution (a Modify action can be added back, with the appropriate semantics, if and when we specify an object-oriented dialec). What shall we do? Christian IBM 9 rue de Verdun 94253 - Gentilly cedex - FRANCE Tel. +33 1 49 08 35 00 Fax +33 1 49 08 35 10
Received on Tuesday, 19 January 2010 12:13:45 UTC