Difference between revisions of "1993 OIM Problems/Problem 6"

 
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== Problem ==
 
== Problem ==
Two non-negative integers <math>a</math> and <math>b</math> are ''mates'' if the decimal expression <math>a+b</math> consists only of zeros and ones. Let <math>A</math> and <math>B</math> be two infinite sets of non-negative integers, such that <math>B</math> is the set of all numbers that are ''mates'' of all the elements of <math>B</math>.
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Two non-negative integers <math>a</math> and <math>b</math> are "''mates''" if the decimal expression <math>a+b</math> consists only of zeros and ones. Let <math>A</math> and <math>B</math> be two infinite sets of non-negative integers, such that <math>B</math> is the set of all numbers that are "''mates''" of all the elements of <math>B</math>.
  
 
Prove that in one of the sets <math>A</math> or <math>B</math> there are infinitely many pairs of numbers <math>x</math>, and <math>y</math> such that <math>x-y = 1</math>.
 
Prove that in one of the sets <math>A</math> or <math>B</math> there are infinitely many pairs of numbers <math>x</math>, and <math>y</math> such that <math>x-y = 1</math>.

Latest revision as of 14:22, 13 December 2023

Problem

Two non-negative integers $a$ and $b$ are "mates" if the decimal expression $a+b$ consists only of zeros and ones. Let $A$ and $B$ be two infinite sets of non-negative integers, such that $B$ is the set of all numbers that are "mates" of all the elements of $B$.

Prove that in one of the sets $A$ or $B$ there are infinitely many pairs of numbers $x$, and $y$ such that $x-y = 1$.

~translated into English by Tomas Diaz. ~orders@tomasdiaz.com

Solution

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See also

https://www.oma.org.ar/enunciados/ibe8.htm