Math 2.0

Real functions Definition

Limit point of a set

Definition

Let SS be a subset of ℝ\mathbb{R} and let aa be a real number. The point aa is a limit point of SS if for each δ>0\delta > 0 there is x∈Sx \in S with 0<∣x−a∣<δ0 < |x - a| < \delta.

Remarks

A limit point of SS need not belong to SS. For example, 00 is a limit point of {1/n:n≥1}\{1/n : n \ge 1\}. Each point of an interval with more than one point is a limit point of the interval. So are its endpoints. Limit points of the domain are the points where the limit of a function makes sense. Mathlib uses the general form AccPt.

Where this leads

363 pages build on this one.

Further reading

  1. Web https://en.wikipedia.org/wiki/Accumulation_point, Accumulation points of a set
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Tag07EGCNHAVW
URIm2://07EGCNHAVW
Aliasescluster-point-of-a-set
Kinddefinition
WritingW1 stated
MSC26A03
DefinesLimit point

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