# Structural properties of addition and multiplication.

People often speak about multiplicative groups or additive groups referring to the operation that is defined on the set of interest. My question is: are there some intrinsic properties of these operations (other than those associated with the group structure) that let one to qualify a operation as a "multiplication" or an "addition"?. In other words: is there any structural definition of "addition" or "multiplication"? . If both meet group properties, what else tells one from the other from a structural point of view?

• There's no real meaning behind calling a group additive or multiplicative (with the exception that by tradition nonabelian groups are not written additively). They're just words and associated notation, no formal difference.
– neth
Apr 7, 2016 at 7:38

## 1 Answer

No, people consider an operation to be an addition or a multiplication according to their own intuition about the structure. Sometimes one is more natural to the other, and people choose accordingly.

There are still some kind of general conventions : an addition is always commutative (it's very bad practice to use $+$ to denote a non-commutative operation), and an operation that is some kind of "function composition" (in a vague and large sense) is generally multiplicative.

• But not too vague and large; all group operations are function composition if you squint a bit.
– neth
Apr 7, 2016 at 7:43