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Re: Question about Hold

• To: mathgroup at smc.vnet.net
• Subject: [mg48833] Re: Question about Hold
• From: drbob at bigfoot.com (Bobby R. Treat)
• Date: Fri, 18 Jun 2004 02:13:02 -0400 (EDT)
• References: <carjrn$r76$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

A few questions:

1) Why write A*A as if that's different from A^2? (It isn't.)

2) Why use Hold[A*A] if you want the argument evaluated?

3) What do you want Commute[Hold[A*A],B] to evaluate to? (Commute[A,C], I suppose.)

4) What have you done to make it happen? Just Commute[A,B]=C? Or something else.

5) Are we mind-readers?

Bobby

Daohua  Song <ds2081 at columbia.edu> wrote in message news:<carjrn$r76$1 at smc.vnet.net>...
> Hi,evryone,
>     I define a commute relation for quantum operators,i fact i learn this 
> from the forum.Here is the problem.
>     Commute[A,B]=C.
>     Commute[A^2,B], i try to use Hold[A*A] instead of A^2, then mathematica 
> even won't evaluate it.!
>     Any suggestion to work on the power commutation?
>     Thanks
> Daohua