On Dec 6, 2012, at 12:03 PM, Joe Niederberger <niederberger@comcast.net> wrote:

He (Martinez) didn't, so what is it? Keep addition as is, but be willing to change the usual rules of multiplication in order to impose the new sign rule: (-) x (-) = (-). 

He seems to have invented something altogether different than the "sign" we know. So I don't think it is correct to compare "rules" just because the two systems use the same symbol. In his system, the minus sign would equate to what we call "i".

Bob Hansen