Math 2.0

definition

Commutative ring

Definition

A commutative ring is a ring RR such that a⋅b=b⋅aa \cdot b = b \cdot a for all a,b∈Ra, b \in R.

Remarks

The integers Z\mathbb{Z}, the rational numbers Q\mathbb{Q} and the polynomials in one variable over Q\mathbb{Q} are commutative rings. The ring of 2×22 \times 2 real matrices is not commutative. Every field is a commutative ring.

Explanations

L1 human

In a commutative ring, the order of the factors in a product does not matter. The integers are the model: 3⋅5=5⋅33 \cdot 5 = 5 \cdot 3.

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  1. Group concept
  2. Ring definition
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Sources

  1. Web https://en.wikipedia.org/wiki/Commutative_ring, Definition