Eckmann-Hilton (Was: Tensor of monads)

Sergey Goncharov wrote in part:

But I guess, Eckmann-Hilton argument does not apply to your previous example because it presupposes that the monoidal structures share the unit, which was not the case there, was it?

Actually, the requirements for Eckmann-Hilton are surprsingly weak! As long as you have two binary operations on a given set, each with its own unit, where one is a homomorphism WRT the other, then everything else (associativity, same unit, etc) follows. See http://ncatlab.org/nlab/show/Eckmann-Hilton+argument for details. --Toby [For admin and other information see: http://www.mta.ca/~cat-dist/ ]