First countability axiom

Limit points are limits of convergent subsequences in a first-countable space

Let 𝑋 be a first-countable topological space and (π‘₯𝑛)βˆžπ‘›=1 βˆˆπ‘‹ be a sequence. Then π‘Ž βˆˆπ‘‹ is a Limit point of π‘₯𝑛 iff there exists a convergent subsequence (π‘₯𝑛𝑖)βˆžπ‘–=1 β†’π‘Ž. topology


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