Is Infinity a Point in $\mathbb{R}$?”

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SUMMARY

The discussion centers on the concept of infinity in the context of closed sets within the real numbers, specifically addressing whether infinity can be considered a point in the real number system, $\mathbb{R}$. It is established that a closed set in $\mathbb{R}$ is defined such that the limit of any convergent sequence within it must also belong to the set. The conversation clarifies that while sequences can converge to infinity, this notion is only applicable within the extended real numbers, $\bar{\mathbb{R}}$, and not within the standard real numbers, $\mathbb{R}$. Therefore, sequences converging to infinity do not qualify as convergent in the realm of real numbers.

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We defined the definition of a closed set to be:

"[tex]F\subset\mathbb{R}[/tex] is closed if the limit of any convergent sequence in F is an element of F."

Now we have also defined that a sequence may "converge to infinity". Is infinity considered a point in N?
 
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Now we have also defined that a sequence may "converge to infinity".
[itex]\pm\infty[/itex] are elements of the extended real numbers, not the real numbers. Converging to infinity only makes sense when working within the extended reals.

So if you're working over the reals, then "converge to infinity" doesn't make sense, because the reals have no such element. A sequence that would converge to (plus) infinity in [itex]\bar{\mathbb{R}}[/itex] is not a convergent sequence in R.
 

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