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

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

In article <hhhmhl$o48$1 at>,
 Valeri Astanoff <astanoff at> 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, 

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?

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