All Questions
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Question on elementary set theory notation
Consider the set $A=\{n\ a \}$ where $a>0$ is a constant and $n \in \mathbb{N}$
How shall we write this set $A$ in set theory?
If we write it as $A=\{n\ a\ \backslash n \in \mathbb{N}, a>0 \}$ ...
- 1,141
0
votes
1
answer
718
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Can $\mathbb{N}$ be an element of $\mathbb{R}$
Is $\mathbb{N}$ a element of $\mathbb{R}$
I understand that $\mathbb{N}$ ⊆ $\mathbb{R}$, but does that also imply that $\mathbb{N}$ ∈ $\mathbb{R}$?
- 3
1
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2
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246
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Proof that the set of Natural numbers are equal to the Real numbers [duplicate]
Obviously the proof is flawed in some way, but I have been struggling to find out where the flaw is.
I am self taught and fairly new to set theory so the flaw may be obvious (sorry):
The idea is that ...
user570801
0
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3
answers
364
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The set of all digits in a real number
Is the set of all digits in a real number countable/listable? It seems to me that it is, based merely on my layman's reading of popular books about set theory. In other words, it seems that one can ...
- 101
0
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1
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346
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Countability of real numbers in $(0, 1)$ [closed]
I've been reading a basic book on set theory for a while now. And recently ran into an uncountability of $(0, 1)$. I guess like almost everyone who tries to understand what he or she reads I tried to ...
- 103