> On 2016-06-27, at 16:05, Peter F. Patel-Schneider <pfpschnei...@gmail.com>
> wrote:
>
> […]
>
> Project(
> { (x,:b) |
> eval( D(G),
> substitute(
> Join(
> Extend( Z, y, :c ) ,
> ToMultiset( Project( ToList( BGP(?z :d ?x) ) , z ) )
> )
> (x,:b) )
> ) /= { } } ,
> x
> )
>
> Project(
> { (x,:b) |
> eval( D(G),
> Join(
> Extend( Z, y, :c ) ,
> ToMultiset( Project( ToList( BGP(?z :d :b) ) , z ) )
> )
> ) /= { } } ,
> x
> )
if i follow this, this reduction obtains iff the project has no effect on the
scope the binding for ?x which was established by the outer extend.
is that intended?
best regards, from berlin,
---
james anderson | ja...@dydra.com | http://dydra.com
