Re: Idempotence and "Replication Insensitivity" are equivalent ?

William Hughes wrote:
>
> This is silly. I have a function f:A,A->A, but this is
> too restrictive so I will change this to a function f:A,B->B,
> but now I want to talk about idempotence so I will
> let A=B, so I have a function f:A,A->A but this is
> too restrictive so ...

I have no idea what you're trying to say here.

Anyway, A, B -> B as the most general type of a the first argument to fold is not my formulation; it's been around for a long time. I would prove that with a Google search, but alas! Google throws away most punctuation, and the first hit for "A, B -> B" is "The Official BB King Website."

> Have I got this straight.
>
> S can contain an arbitrary number of elements of A,
> so f(a,S) takes an arbitrary number of elements of A, but
> f is despite this a binary form?

No; I wouldn't call it binary unless A = B. But is this question really important? Boy you are really hung up on nomenclature. :-)

Marshall Received on Wed Sep 20 2006 - 22:26:55 CDT