Re: More /.{I->-1} craziness

*To*: mathgroup at smc.vnet.net*Subject*: [mg106525] Re: More /.{I->-1} craziness*From*: AES <siegman at stanford.edu>*Date*: Fri, 15 Jan 2010 03:20:02 -0500 (EST)*Organization*: Stanford University*References*: <hhf5s3$h4o$1@smc.vnet.net> <hhhmhl$o48$1@smc.vnet.net>

In article <hhhmhl$o48$1 at smc.vnet.net>, Valeri Astanoff <astanoff at gmail.com> wrote: > > Imho, when applying a rule lhs -> rhs > it's a risky practice to use the same symbol > in 'lhs' and 'rhs', because, very often, there is > no easy way to check what has been done. > > Anyway, for occasional users, you're right : it's crazy! > Thank you -- that's really my primary point. And I'd add: it's damaging (to users, and to Mathematica). As for writing rules, I'd not even try writing something compound, like a + b or especially something like 1 + I, on the lhs, because I'd have no intuition as to how this would work (how spaces would be handled, etc.) But a single character on the lhs? It works correctly AFAIK for every other single-character in the alphabet. Why shouldn't one expect it to work for I?

**Follow-Ups**:**Re: Re: More /.{I->-1} craziness***From:*Daniel Lichtblau <danl@wolfram.com>