Re: [TED] Question on constraints

Hassan Aït-Kaci wrote:
> 
> (3) other data models may be accommodated using this "data model as
>     constraint system" paradigm and conjugated with definite clauses
>     using the CLP scheme in order to obtain Horn-like rule systems
>     over varied data types (e.g., Java, C#, or C++ classes/objects).
> 

We agreed that RIF would specify a common expression language from which 
the various RIF dialects will draw (by restricting which expressions are 
allowed in the LHS/condition, RHS/conclusion, and constraint expressions 
[1]).

[1] E.g., CORE will probably allow only a conjunction of atoms in the 
body and a single atom in the head.

Don't we need to associate constraints to said language expressions, 
instead of at the rule level only (as we discussed and decided at F2F4), 
if we want that good property of data model abstraction brought by the 
constraint paradigm to apply to the ground arguments and locally bound 
variables in the expressions?

If not, how comes that we do not need to abstract the data model in 
order to agree on the semantics of expressions in the expression 
language, but we need it for rules (or that the abstraction can be 
implicit at the expression level but not at the rule level)?

Christian

Received on Tuesday, 28 November 2006 15:43:56 UTC