Frame VS objects (Was: Re: [PRD] PRD TF telecon Tuesday 14 October)

Hassan Ait-Kaci wrote:

>  > The question seems to be, really, if we can expect that the author
>  > of a BLD compatible rule set (program) always knows (at authoring
>  > time) whether a given frame's slot is, essentially, multi- or 
> single-valued.
> 
> To me, that author had better know what s/he wrote! So, *of course*, the
> *author* of the rules knows what s/he wrote. How many programmers do you
> know that write programs not knowing what the semantics of what they write?
> My point is that one can always declare this intended semantics, and the
> setup thet I propose takes care of that seemlessly (modulo the amendment
> of the collection semantics from sets to monoids).

So that the solution would be to differentiate, in the syntax of Frames, between the multivalued case (o[p->v], where o[p->v1 is not contradictory with o[p->v2]) and the single-valued case (e.g. o[p=v], where you cannot have both o[p=v1] and o[p=v2], unless v1=v2), and allow only the single-valued case in PRD (and have some kind of transform from -> to =, as you describe, for the BLD2PRD interchange)?

Christian