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= The Erdos-Woods Problem =
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= The Erdös-Woods Problem=
  
This page introduces a problem considered by Erdos and Woods.
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The Erdös-Woods problem is a surprisingly far reaching question about integers. I has implications for mathematical logic, [[ABC triples]], [[elliptic curves]], and can be generalized to (affine) [[schemes]]. This generalization provides links between number theory and Nivanlina's value distribution theory in complex analysis. Connections between Nivanlina theory and number theory have already been emphasized by Lang and Vojta in connections with Roth's theorem. This completely independent connection suggests that the ABC conjecture could stated for the ring of entire functions. I seems plausible that it could even be proven in the context of Nivanlina theory.
 
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'''Defintion (Radical)''': The radical of a positive integer n is simply the product of all those prime numbers p which divide n.
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'''Remark''': There are no prime numbers which divide 1, so rad(1) is the product of all the elements in the empty set. The only reasonable value to choose for this number is 1.
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To compute rad(n) in sage, define the following simple function.
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sage: def rad(n):<br>....: return prod(n.prime_divisors())<br>....: <br>sage: rad(256)<br>2<br>sage: rad(210)<br>210<br><br>
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The rad(n) is a function with some very nice properties. It also behaves well with respect to the function gcd(A,B).
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'''Proposition / Definition (Squarefree)''' Let $n > 0$ be an integer. The following are equivalent:
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(a) $\text{rad}(n) = n$
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(b) There does not exist an integer $d > 1$ such that $d^2$ divides $n$.
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'''Exercise 1:''' Suppose that A and B are positive integers. Show that:
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gcd(rad(A),rad(B)) = rad(gcd(A,B))
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and
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rad(AB) = rad(A)rad(B)/rad(gcd(A,B))
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== The Evil Wizard  ==
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Suppose you are confronted by an evil wizard who presents you with the following challenge:
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"'''I'm going to pick a positive integer $n &gt; 1$ and then I shall tell you the radical of each integer from $n$ to $n+k$. Then you must tell me what $n$ is.'''"
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For which $k$ should you accept this challenge? Discuss...
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Revision as of 09:40, 3 August 2010

The Erdös-Woods Problem

The Erdös-Woods problem is a surprisingly far reaching question about integers. I has implications for mathematical logic, ABC triples, elliptic curves, and can be generalized to (affine) schemes. This generalization provides links between number theory and Nivanlina's value distribution theory in complex analysis. Connections between Nivanlina theory and number theory have already been emphasized by Lang and Vojta in connections with Roth's theorem. This completely independent connection suggests that the ABC conjecture could stated for the ring of entire functions. I seems plausible that it could even be proven in the context of Nivanlina theory.

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