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Re: Simplify with NestedLessLess?

• To: mathgroup at smc.vnet.net
• Subject: [mg106537] Re: [mg106487] Simplify with NestedLessLess?
• From: "David Park" <djmpark at comcast.net>
• Date: Fri, 15 Jan 2010 03:22:18 -0500 (EST)
• References: <23979164.1263466810832.JavaMail.root@n11>

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