Re: b-nodes in rule conclusions

On Mon, 2007-04-30 at 20:17 -0400, Sandro Hawke wrote:
> 
> Here's a test (motivated by a current discussion in RIF-WG):
> 
>    <a> <b> <c>.
>    <a> <b> <d>.
>    { <a> <b> ?x } => { _:x <b_inferred> ?x. }.
>    _:x <b_given> <c>.
>    _:x <b_given> <d>.
> 
> The (relevant) output I get from cwm is:
>    
>    [ <b_given> <c>, <d> ].
>    [ <b_inferred> <c> ].
>    [ <b_inferred> <d> ].
> 
> which makes it clear that the "_:x" inside the rule conclusion does not
> name the same thing as the other "_:x"'s in the file do.  In other
> words, b-nodes in rule conclusions get an implicit existential
> quantifier inserted.  They don't just use the implicit one around the
> file.
> 
> Two questions: (1) is that as it should be?

yes, I'm pretty sure that's by design.
I'm pretty sure we captured that design decision in tests.

>                (2) how strongly do you feel that way?   (would it
>                    be reasonable to do it the other way, perhaps?)

It might be reasonable to say "don't do that" in response
to using _:x in different scopes, but I don't
think it's reasonable to use the syntax above to mean something else.

-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
D3C2 887B 0F92 6005 C541  0875 0F91 96DE 6E52 C29E