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Re: Simplify with NestedLessLess?

• To: mathgroup at smc.vnet.net
• Subject: [mg106521] Re: [mg106487] Simplify with NestedLessLess?
• From: Dave Bird <dbird at ieee.org>
• Date: Fri, 15 Jan 2010 03:19:16 -0500 (EST)
• References: <23979164.1263466810832.JavaMail.root@n11> <003e01ca951d$e3bc9e60$ab35db20$@net>
• Reply-to: dbird at ieee.org

Thanks David. Good point.

But, my example was just to illustrate in principle. My actual needed 
usage is in much more complicated expressions.

Thanks again,

Dave

David Park wrote:
> Why should it Simplify d? NestedLessLess has no built-in meaning. And even
> if it did mean that b << a there is no reason that Mathematica should still
> set b to zero. It doesn't even know if a and b are real positive. You will
> have to set it to zero yourself.
>
> d /. b -> 0  
> a
>
> For more complicated expressions you might have to use Limit.
>
>
> David Park
> djmpark at comcast.net
> http://home.comcast.net/~djmpark/  
>
>
>
> From: dbird [mailto:dbird at ieee.org] 
>
> Please excuse if this has been answered before, but I can't find it.
>
> Is there some way to do a Simplify with assumptions using a 
> NestedLessLess or something similar? For example:
>
> d=a+b
> Simplify[d,NestedLessLess[a,b]]
>
> Answer is:
> a+b
>
> Answer should be:
> b
>
> Thanks,
>
> Dave
>
>
>
>