Commit a51b0fe0 authored by Ralf Jung's avatar Ralf Jung

explain the use of \bot for masks

parent a5f94780
......@@ -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:
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