1
The whole of theorem $5$ of this paper Some further results on ideal convergence in topological spaces by Pratulananda Das is unclear to me. Theorem $\mathbf{5}$. For any sequence $x = (x_n)_{n\in\mathbb N}$ in a hereditarily Lindelöf space $X$, there exists a sequence $y = (y_n)_{n\in\ma...