Proving: Neighborhoods of x and y Have Empty Intersection

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Homework Help Overview

The problem involves proving the existence of neighborhoods around two real numbers, x and y, such that the intersection of these neighborhoods is empty. This falls under the subject area of real analysis and topology.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the concept of neighborhoods and how to define them around x and y. There is an exploration of the idea of choosing the "tightness" of these neighborhoods and the implications of the distance between x and y.

Discussion Status

The discussion is ongoing, with participants providing hints and suggestions for approaching the proof. Some guidance has been offered regarding the choice of neighborhood sizes, but no consensus or complete solution has been reached yet.

Contextual Notes

There is an assumption that x and y are distinct real numbers, which is central to the discussion about the distance between them and the possibility of defining non-overlapping neighborhoods.

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Homework Statement


Let x and y be real numbers. Prove there is a neighborhood P of x and a neighborhood Q of y such that P intersection Q is the empty set.


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The Attempt at a Solution



Sorry, I know this is elementary to many of you, but I am just starting out in this course and I need some hints on how to get started.
 
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It is asking "can you fit a pair of brackets around x and another pair of brackets around y such that the two pairs of brackets do not touch each other?" Remember, you are the one choosing how tight the first pair of brackets (around x) as well as how tight the second pair (around y). (You can make them as tight as you want.)
 
Pictorially it would be something like this:

<---------------(---x---)---------(-----y-----)--------------->

...but this diagram does not constitute a proof. I do not know how to make it into a rigorous argument. I have the sets (x-r, x+r) and (y-s, y+s) but I don't know what to do with them.
 
If x and y are different then they have some non-zero distance between them. Think about neighborhoods of x and y with radius equal to 1/3 that distance.
 

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