Continuous Mappings into Hausdorff Space coinciding on Everywhere Dense Set coincide/Proof 2

Proof
Let $x \in X$.

Since $D$ is everywhere dense, we have that $x \in \map \cl D$, where $\map \cl D$ is the topological closure of $D$.

By Point in Set Closure iff Limit of Moore-Smith Sequence, there exists a directed set $\struct {\Lambda, \preceq}$ and a Moore-Smith sequence $\family {x_\lambda}_{\lambda \in \Lambda}$ in $D$ converging to $x$.

From Characterization of Continuity in terms of Moore-Smith Sequences, we have that the Moore-Smith sequences $\family {\map f {x_\lambda} }_{\lambda \in \Lambda}$ and $\family {\map g {x_\lambda} }_{\lambda \in \Lambda}$ converge to $\map f x$ and $\map g x$ in $\struct {Y, \tau_Y}$ respectively.

By hypothesis, we have:


 * $\map f {x_\lambda} = \map g {x_\lambda}$ for each $\lambda \in \Lambda$.

So we have that $\family {\map f {x_\lambda} }_{\lambda \in \Lambda}$ converges to both $\map f x$ and $\map g x$.

Since $\struct {Y, \tau_Y}$ is Hausdorff, from Characterization of Hausdorff Property in terms Moore-Smith Sequences we obtain that $\map f x = \map g x$, hence the demand.