Proving a Division Algorithm for Real Numbers?

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Discussion Overview

The discussion revolves around proving a Division Algorithm for real numbers, specifically exploring the representation of a real number x in terms of another real number α, where x can be expressed as x = kα + δ for some integer k and real number δ, with constraints on δ. The focus includes both the uniqueness of the representation and the existence of such k and δ.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested, Mathematical reasoning

Main Points Raised

  • One participant questions how to prove the uniqueness of k and δ, suggesting that if it were not unique, subtracting one representation from another would lead to a false equation.
  • Another participant expresses uncertainty about how to demonstrate the existence of k and δ.
  • A different approach is proposed, indicating that the sequence na for n=1,2,... is unbounded, suggesting that for some n, na will exceed x, and that finding a lowest bound can help determine k.
  • Another participant suggests a more straightforward method by letting k equal the floor of x divided by α.

Areas of Agreement / Disagreement

Participants express differing views on how to approach the proof, particularly regarding the uniqueness and existence of k and δ. The discussion remains unresolved as multiple methods and perspectives are presented without consensus.

Contextual Notes

Some assumptions about the properties of real numbers and the definitions of the floor function and bounded sequences are implicit in the discussion, but these are not fully explored or agreed upon.

Doom of Doom
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How might I prove a Division Algorithm for the Real numbers?

That is to say, if [tex]x, \alpha \in \mathbb{R}[/tex], then [tex]x=k \alpha + \delta[/tex] for some [tex]k \in \mathbb{Z},[/tex] [tex]\delta \in \mathbb{R}[/tex] with [tex]0 \leq \delta < \alpha[/tex] where [tex]k, \delta[/tex] are unique.
 
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Assume that it is not unique, subtract one representation from the other. The resultant equation is obviously false.
 
Yeah, but how can I show existence?
 
Doom of Doom said:
Yeah, but how can I show existence?

The sequence na for n=1,2,... is unbounded. Therefore for some n, na>x. Find lowest bound, subtract 1 and you will have k. ka<=x, (k+1)a>x, so x-ka(remainder)<a
 
or even more straightforward, let k = floor(x/a)
 

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