My math-skills are a bit too rusty to qualify the exact nature of the operation, commutativity springs to my mind.And how is reduce() supposed to know whether or not some arbitrary function is commutative?
I don't recall anybody saying it should know that - do you? The OP wants to introduce parallel variants, not replace the existing ones.
Diez -- http://mail.python.org/mailman/listinfo/python-list