Response to NB1

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Thanks for taking the time to provide us with feedback.

Nick Bassiliades wrote:

> Hi list members,
> I believe that the current draft of RIF-BLD is a very good attempt to 
> formalize and put into order multiple common issues related to logic 
> rule representation and exchange. I was happy to see slotted
> arguments and frames and even variables in the place of slots, which 
> gives a flexibility related to querying.
> Although I was not able to go through all the details I strongly believe 
> that this draft has the potential to become a candidate recommendation.
> I have a couple of minor remarks about the text itself and not the 
> language.
> I would like to see a better separation and discussion about the 
> differences between terms with named arguments and frames;
> when is it supposed to use the one or the other.

The potential confusion caused by using the same syntax for both named arguments and frame slots has been a cause of ongoing and unresolved discussion. We hope to have a resolution before the Candidate Recommendation.

However, the choice for which to use is not really explainable. They are very similar notions and thus the choice is one of personal preference. We have provided both as a convenience for mapping to systems that provide one or the other, but they both amount to syntactic sugar.

> Furthermore, more annotation examples would be useful.

We are working on providing many more examples and test cases. You can see the emerging cases at

> Finally, I would suggest a better explanation about the different 
> meaning between atomic formulae and terms. In section 2.3 they are 
> strongly related. However, although their syntax is exactly the same
> and in Prolog they can be used interchangeably,
> their meaning in theory is quite different. Terms are entities, whereas 
> atomic formulae are relationships
> between entities. So, I would suggest a better clarification of this 
> fact there.

I'm not sure how to define it more clearly than it is: "Any term (positional or with named arguments) of the form p(...), where p is a predicate symbol, is also an atomic formula. Equality, membership, subclass, and frame terms are also atomic formulas. " I'm not sure what you mean by "Terms are entities", the semantics specifies what kinds of domain elements each kind of term maps to.

> Otherwise, I believe that the text is very elaborate and accurate.

Thank you for the comments, The RIF WG