It cannot be proved by others.
In fact, I can prove that it cannot be proved
So any element in is an ordered 4-tuple but it is more convient to write . We define the following products:
So for example if we need to multiply we would write and get .
But if .
I leave it to you to verify that has the following properties:
--- > Boring and Long.
---> Boring and Long.
--->Boring and Long.
This show it has everything EXCEPT
*)If the field is finite it is not necesarry. This supprising result is not easy to prove.