Yep. I notice mention of this additional constraint from another comment. As far as I can tell the article is just incorrect since it misses this constraint up to that point, unless I'm just a clown and somehow not seeing it.
The upside here is that it seems perhaps I wasn't missing the premise, and it was just mis-stated :)
No you are right, quanta sucks. Im sure there are thousands of other people thinking of x+1 and scratching their heads
So add "mod p" to it.
Transformation is not continuous at the boundary p