Definition 2.8.11. Let
R be a
ring. We define
R is commutative
by:
[R, ⊕, 0, ⊖, ⊙, 1] is commutative :⇔ ⊙ is commutative (R is a set, ⊕ : R × R → R is an operation on R, 0 ∈ R, ⊖ : R → R is a function, ⊙ : R × R → R is an operation on R, 1 ∈ R such that (R, ⊕, 0, ⊖, ⊙, 1) forms a ring)