n style="font-weight: bold; font-style: italic;">L</span> = <span
 style="font-family: arial; font-style: italic;">base</span>(<span
 style="font-style: italic; font-weight: bold;">T</span>), whose
closure <span style="font-family: arial; font-style: italic;">clo</span>(<span
 style="font-style: italic; font-weight: bold;">T</span>) = (<span
 style="font-family: arial; font-style: italic;">base</span>(<span
 style="font-style: italic; font-weight: bold;">T</span>), <span
 style="font-family: arial; font-sty