Proof of the Division Algorithm

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Discussion Overview

The discussion revolves around the application of the well ordering principle (WOP) in the context of the division algorithm, specifically whether it can be applied to subsets of non-negative integers as opposed to just positive integers. The scope includes theoretical aspects of number theory and the implications of the WOP.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant questions whether the well ordering principle, defined for positive integers, can be applied to non-negative integers, expressing concern about being overly pedantic.
  • Another participant asserts that the WOP can indeed be applied to non-negative integers, noting that if zero is included in the subset, it serves as the least element. If zero is not included, the subset can be treated as a subset of positive integers.
  • A third participant summarizes the discussion, reiterating the definition of the WOP and confirming its applicability to any subset of integers that is bounded below.
  • A later reply expresses appreciation for the clarification, indicating that the explanation was clear and obvious.

Areas of Agreement / Disagreement

Participants generally agree that the well ordering principle can be applied to non-negative integers, but the initial question about its applicability indicates some uncertainty regarding the definitions and boundaries of the principle.

Contextual Notes

The discussion does not resolve the nuances of the definitions of subsets or the implications of boundedness, leaving some assumptions about the applicability of WOP in specific contexts unaddressed.

matqkks
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TL;DR
Application of well ordeing principle
In many books on number theory they define the well ordering principle (WOP) as:

Every non- empty subset of positive integers has a least element.

Then they use this in the proof of the division algorithm by constructing non-negative integers and applying WOP to this construction. Is it possible to apply the WOP to a subset of non-negative integers? Am I being too pedantic?
 
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Yes, you can apply it to the non-negative integers, by simply observing that if the subset contains zero then zero is the least element, otherwise the subset is also a subset of the positive integers and we can apply the principle that holds for them.
 
matqkks said:
Summary: Application of well ordeing principle

In many books on number theory they define the well ordering principle (WOP) as:

Every non- empty subset of positive integers has a least element.

Then they use this in the proof of the division algorithm by constructing non-negative integers and applying WOP to this construction. Is it possible to apply the WOP to a subset of non-negative integers? Am I being too pedantic?

Yes, well ordering principle applies to any subset of ##\mathbb{Z}## that is bounded below.
 
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Likes   Reactions: Klystron and nuuskur
Thanks it is so obvious as you have suggested.
 

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