Re: [BLD] comments on BLD draft

Michael Kifer wrote:
>>
>>No, I meant: in "# Equality terms. If t and s are simple, positional, or 
>>named-argument terms then t = s is an equality term.", shouldn't t and s 
>>be allowed to be external terms as well (same for #, ## and frame)?
>>
> I think that equality among external terms should *not* be allowed, since
> it cannot be tested anyway (definition of an external term is a black box
> to a rif document, by definition).

It can be tested by the consumer: if it could not, a RIF document that 
contained external calls would be useless, wouldn't it?

> For instance, one could write External(t) = External(s)
> but these two externals' black boxes might not be equal, and the reasoner
> will have no way of testing that.

I can see that equality or classification terms with external terms may 
be a problem in the head; but in the body?

Christian