If E is infinite, then by the Bolzano-Weierstrass principle it has a limit point x. Since x is a limit point of E, one can choose n1 ∈ N such that |x_(n_1 )-x| < 1. If nk ∈ N have been chosen so that |x_(n_1 )-x| < 1/k , then, because x is a limit point of E, there exists n_(k+1) ∈N such that nk < n_(k+1) and|x_(n_(k+1) ) -x| < 1/(k+1)
Since lim┬(k→∞)〖1/k 〗 = o , the sequence x_(n_1 ) ,x_(n_2 ) ,…,x_(n_k ),.... so constructed conVerges to x. ⎕