But isn't Codd's relational algebra based on 1NF relations? The point of 1NF is (among other things) to make the algebra simpler because you don't need to handl

But isn't Codd's relational algebra based on 1NF relations? The point of 1NF is (among other things) to make the algebra simpler because you don't need to handle nested relations. A database built on non-1NF relations would be very different from Codd's vision.