Understanding the Difference Between 1 and 2 in Natural Numbers

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Discussion Overview

The discussion revolves around the conceptual differences between the natural numbers 1 and 2, particularly in the context of set theory and union operations. Participants explore the implications of defining natural numbers using set notation and the significance of the variable "x" in this context.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant defines 1 as "xUx" and 2 as "xUxUx" and questions the difference between these representations and whether each instance of "x" is distinct.
  • Another participant suggests that sets that are not identical are considered different, questioning the validity of this assertion.
  • A third participant argues that the definition of a set relies on its contents, stating that two sets are equal only if they contain the same elements.
  • A later reply challenges the interpretation of "x" and suggests that if "x" is a single set, then both "xUx" and "xUxUx" would simplify to the same set, raising questions about notation and clarity in mathematical definitions.

Areas of Agreement / Disagreement

Participants express differing views on the interpretation of "x" and the implications of set notation, indicating that multiple competing perspectives remain without a clear consensus.

Contextual Notes

The discussion highlights potential ambiguities in notation and the definitions of mathematical objects, particularly regarding the use of variables and the concept of set equality.

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first of all, id like to thank the admin for taking down a rather embarrassing post I had put up earlier. I'll try to do better this time.

N = any natural number
1 = xUx
2 = xUxUx

What exactly is the difference between 1 and 2? Is each instance of x different? If so, how?
 
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Someone just explained to me that sets that are not each other are different than each other because sets are different than what they are not

True or no?
 
Last edited:
Simmer said:
Someone just explained to me that sets that are not each other are different than each other because sets are different than what they are not

True or no?
?
ANYTHING, whether a set or not, is "different than what they are not"! That's pretty much what "different" means.

I suspect that what they were trying to tell you is that a set is "defined" by what it contains. Two sets are "equal" if and only if they contain exactly the same things.
 
Last edited:
Simmer said:
first of all, id like to thank the admin for taking down a rather embarrassing post I had put up earlier. I'll try to do better this time.

N = any natural number
1 = xUx
2 = xUxUx

What exactly is the difference between 1 and 2? Is each instance of x different? If so, how?
You wrote this- what do YOU intend "x" to mean? Normally, unless something is said to the contrary, one symbol corresponds to one mathematical object. In particular, if x represents one set then both xUx and xUxUx are the same, x, because the union of any set with itself is just itself again. xUx= x so xUxUx= (xUx)Ux= xUx= x.

However, if it is clearly stated that "x" is a "place holder", that "x" is not a specific set but just represents any set, then xUx might mean "the union of any two sets" and xUxUx might mean "the union of any three sets. (Though I would consider that poor notation.)

(What does "N is a natural number" have to do with this?)
 

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