Sunday, March 20, 2005
21:31
Okay, I'm an idiot. The positive integers do not form a group under multiplication. Duh, there's no inverses! They do, however, form a semigroup with an identity, also called a monoid. It's even abelian, but I'm not sure if an abelian monoid has a special name.
# posted by Fibonacci @ 20.3.05 
