@@ -96,7 +96,7 @@ The following assertion states that an invariant with name $\iname$ exists and m

Next, we define \emph{view updates}, which are essentially the same as the resource updates of the base logic ($\Sref{sec:base-logic}$), except that they also have access to world satisfaction and can enable and disable invariants:

\[\pvs[\mask_1][\mask_2]\prop\eqdef W *\ownGhost{\gname_{\textmon{En}}}{\mask_1}\wand\upd\diamond(W *\ownGhost{\gname_{\textmon{En}}}{\mask_2}*\prop)\]

Here, $\mask_1$ and $\mask_2$ are the \emph{masks} of the view update, defining which invariants have to be (at least!) available before and after the update.

We use $\top$ as symbol for the largest possible mask, $\mathbb N$.

We use $\top$ as symbol for the largest possible mask, $\mathbb N$, and $\bot$ for the smallest possible mask $\emptyset$.

We will write $\pvs[\mask]\prop$ for $\pvs[\mask][\mask]\prop$.

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View updates satisfy the following basic proof rules: