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   transcendence of the agm
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   Author  Topic: transcendence of the agm  (Read 373 times)
JocK
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transcendence of the agm  
« on: Jan 16th, 2005, 12:00pm »
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Is the arithmetic-geometric mean* of any two positive integers M and N other than M = N transcendental?  
 
 
 
* The arithmetic-geometric mean agm(A,B) of two numbers A and B is defined as:
 
agm(A,B) = limn[to][infty] an
 
with:
 
a0 = A,  an+1 = (an + bn)/2
b0 = B,  bn+1 = [sqrt](an bn)
 
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solving abstract problems is like sex: it may occasionally have some practical use, but that is not why we do it.

xy - y = x5 - y4 - y3 = 20; x>0, y>0.
Barukh
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Re: transcendence of the agm  
« Reply #1 on: Jan 18th, 2005, 10:52am »
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My guess is that the answer is yes, but I don't have any idea how to prove this. It looks like a very tough problem...
 
The only approach I tried is to show that every iteration of the AGM sequence increases the degree of the polynomial that an, bn can be. But this is not true.
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