Cauchy Sequence
Cauchy Sequence is a sequence whose elements become arbitrarily close to each other as the sequence progresses.
A sequence \(x_1, x_2, x_3, \ldots\) is Cauchy if for every positive real number \(\epsilon\) there exists a positive integer N such that for m, n > N
\begin{equation*} |x_m - x_n | < \epsilon \end{equation*}
If all cauchy sequence converge in the space then the space is complete.
