Phrase for the day: Abelian Groups

In mathematics, an abelian group, also called a commutative group, is a group (G, *) such that

a * b = b * a

for all a and b in G. In other words, the order of elements in a product doesn’t matter. Such groups are generally easier to understand.

Abelian groups are named after Niels Henrik Abel. Groups that are not commutative are called non-abelian (rather than non-commutative).

From Wikipedia

For Ron and Douglas, who surely understand this joke:

Abelian groups

What’s abelian and purple? An abelian grape!

Definition 5.6.1 Let $ g$ and $ h$ be two elements of a group $ G$. We say that $ g$ commutes with $ h$ (or that $ g, h$ commute) if $ g*h=h*g$. We call a group commutative (or abelian) if every pair of elements $ g, h$ belonging to $ G$ commute. If $ G$ is a group which is not necessarily commutative then we call $ G$ noncommutative (or nonabelian).

Example 5.6.2 The integers, with ordinary addition as the group operation, is an abelian group.

Now the reader should understand the punchline to the joke quoted at the beginning! (Let uncontrolled laughter ensue!)

From some smart Navy site

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