3
[0MT] Given a sequence \((x_ n)_ nβ X\) and \(xβ X\),
we will say that β\((x_ n)_ n\) converges to \(x\)β if \(\lim _ n d(x_ n,x)=0\); we will also write \(x_ nβ_ n x\) to indicate that the sequence converges to \(x\).
We will say that β\((x_ n)_ n\) is a Cauchy sequenceβ if
\[ β \varepsilon {\gt}0~ ~ β Nββ~ ,~ β n,mβ₯ N~ ~ d(x_ n,x_ m){\lt}\varepsilon ~ ~ . \]