Proving the Existence of a Color-Matching Rectangle

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SUMMARY

The discussion centers on proving the existence of a rectangle with vertices of the same color on a plane colored in blue and red. The solution involves applying the Pigeonhole Principle, which states that if there are more items than containers, at least one container must hold multiple items. Specifically, in this context, the infinite nature of the colored plane ensures that there will be a rectangle formed by vertices of the same color due to the finite number of color combinations available.

PREREQUISITES
  • Pigeonhole Principle
  • Basic concepts of combinatorial geometry
  • Understanding of infinite sets
  • Familiarity with proof techniques in mathematics
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  • Explore combinatorial geometry and its applications
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DaveElliott
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Homework Statement


A plane is colored blue and red in any way . Prove that there exists a rectangle with vertices of the same color


Homework Equations



Its obviously true.

The Attempt at a Solution



I was thinking proofy by pig hole, but haven't quite figured it out.
 
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It is called the pigeon hole principle: if there are more pigeons than pigeon holes, then there is at least one pigeon hole containing more than one pigeon.

In the infinite sense (useful for this problem): if there are infinitely many pigeons and finitely many pigeon holes, then there is at least one pigeon hole containing infinitely many pigeons.

In this problem, what are the pigeon holes?
 

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