- From: Christian de Sainte Marie <csma@ilog.fr>
- Date: Thu, 14 Jun 2007 19:30:15 +0200
- To: Gary Hallmark <gary.hallmark@oracle.com>
- CC: RIF WG <public-rif-wg@w3.org>
Gary Hallmark wrote: >> >>> I like the ability to have ground facts not wrapped in a forall. >>> I don't like the ability to have free variables (not scoped in a forall) >> >> This is specifically excluded in the deifinition I propose. > > Well, it's not excluded in the syntax. I'd rather have syntactic > enforcement rather than "footnote enforcement" (where possible using a > context-free grammar). I'd like that too, but... > I proposed a syntax that clearly forces wrapping > variables in a forall AND clearly avoids having to wrap ground facts in > a forall. ...your proposal, like the current abstract syntax and other alternatives I considered, forces an Implies to be wrapped in a Forall; it does not preclude variables to be left hanging free in the Implies, however. Example: Forall X, P(X,Y) :- Q(X,Y) So, your proposal, like mine, the current abstract syntax and any other solution I have seen proposed or I could imagine, requires what you poetically call "footnote enforcement" :-( I think Harold said during the discussion Tuesday that that requirement of having all the free variables within the scope of a forall could not be caught using a context-free grammar: Harold, is that what you said? Just for the sake of completeness, because I am not sure that it has any practical impact: your proposed design requires that a ground Implies be wrapped in a Forall, too... Cheers, Christian
Received on Thursday, 14 June 2007 17:30:55 UTC