[E-Lang] Operator expansion names, Part 1: Intro

[Mark S. Miller]

At 04:28 PM Monday 4/9/01, Bill Frantz wrote:
>Normal addition obeys the rule: a + b equals b + a.  If the goal is to
>encourage people building types to model the mathematical concepts of group
>and ring, then we want:
>
>If a and b are in T, then a + b is always in T
>a + 0 equals a
>a + b equals b + a
>(a + b) + c equals a + (b + c)
>
>My naive belief is that bags and sets obey these rules.

What's it called when we have these properties except for commutativity?  I 
don't want to specify that "+" is generally commutative.


        Cheers,
        --MarkM