[cha42]

Any syntax with a let operator to name stuff or a lambda abstraction.

[almostgotcaught]

That only gives you trees not DAGs - you can't do fan-in (there's no way to "share" let bound names).

[mathnmusic]

Isn't this fan-in?

let A = select * from tbla

let B = select * from tblb

let C = select * from A join B

[almostgotcaught]

Think about what tbla and tblb can be - hint they can only be globals (ie actual tables)