Definition 10.7.1 (Hausdorff Completion of TVS).label Let $E$ be a TVS over $K \in \RC$, then there exists $(\wh E, \iota)$ such that:

  1. (1)

    $\wh E$ is a complete Hausdorff TVS.

  2. (2)

    $\iota \in L(E; \wh E)$.

  3. (U)

    For any $(F, T)$ satisfying (1) and (2), there exists a unique $\ol{T}\in L(\wh E; F)$ such that the following diagram commutes:

Moreover,

  1. (4)

    $\iota(E)$ is dense in $\wh E$.

The pair $(\wh E, \iota)$ is the Hausdorff completion of $E$.

Proof. All claims of (1), (2), (U), and (4), except the linearity of maps and the fact that $\wh E$ is a TVS is proven via the Hausdorff completion.

Using Proposition 6.6.5, identify $\wh E \times \wh E$ with $\wh{E \times E}$ and $K \times \wh E$ with $\wh{K \times E}$ as uniform spaces. By Proposition 6.6.4, there exists operations $\wh E \times \wh E \to \wh E$ and $K \times \wh E \to \wh E$ such that the following diagrams commute

\[\xymatrix{ \widehat E \times \widehat E \ar@{->}[r] & \widehat E & & K \times \widehat E \ar@{->}[r] & \widehat E \\ E \times E \ar@{->}[u] \ar@{->}[r] & E \ar@{->}[u] & & K \times E \ar@{->}[u] \ar@{->}[r] & E \ar@{->}[u] }\]

By continuity and the density of $\iota(E)$ in $E$, $\wh E$ with these operations forms a TVS, and $T$ is linear.$\square$