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Re: Replace and ReplaceAll -- simple application

  • To: mathgroup at
  • Subject: [mg106155] Re: Replace and ReplaceAll -- simple application
  • From: DrMajorBob <btreat1 at>
  • Date: Sun, 3 Jan 2010 03:41:10 -0500 (EST)
  • References: <hhkjce$5aq$> <>
  • Reply-to: drmajorbob at

It's beating a dead horse, but I gotta mostly agree with Richard's  
sentiments, here.

Mathematicians spend much of their time doing substitutions, so it doesn't  
wash to say substitution is syntactical, not mathematical.

That said, we'd have to unravel a great deal, if we stopped using FullForm  
to explain pattern matching.


On Sat, 02 Jan 2010 04:04:36 -0600, Richard Fateman  
<fateman at> wrote:

> Bill Rowe wrote:
> ...
>> Do you have some definition for "bug" other than performance in
>> a manner different than documented?
> Yes.
>> That is, failure of any software to do what a user expects is
>> certainly not a bug if that is what the software is documented
>> to do.
> False.
> Here's why.  By your definition, no program has a bug if the programmer
> asserts that the program, by virtue of being written in a high-level
> language, is its own readable documentation. Therefore anything that
> the program does is documented by its own code and therefore is not a  
> bug.
> or in the immortal words of Peewee Herman "I meant to do that".
>> The key problem here is a novice user of Mathematica might think
>> of using replacement rules as doing mathematics.
> Maybe he was confused by the title
> "Mathematica -- A System for Doing Mathematics",  and thought that
> Mathematica was a system for doing mathematics.
>   That simply
>> isn't the case.
> Apparently you thought that Mathematica was "A system for doing
> rule-based syntactic transformations on FullForm expressions which may
> or may not correspond to what is displayed"
>   And since replacing one thing with another is
>> not mathematics, insisting the result makes sense mathematically
>> simply isn't a realistic expectation.
> TaDa.  I couldn't have expressed it better myself.  Insisting that the
> results of a transformation is mathematically consistent, "isn't a
> realistic expectation."
> Which, in my view, demonstrates the existence of a bug.
>   I suppose one could try to determine who is right by a survey,  or ask
> people in the street what they think.

DrMajorBob at

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