validity persists

docs/derived.tex

@@ -47,7 +47,7 @@ We collect here some important and frequently used derived proof rules.
 \end{defn}
 
 Of course, $\always\prop$ is persistent for any $\prop$.
-Furthermore, by the proof rules given above, $t = t'$ as well as $\ownGGhost{\mcore\melt}$ and $\knowInv\iname\prop$ are persistent.
+Furthermore, by the proof rules given in \Sref{sec:proof-rules}, $t = t'$ as well as $\ownGGhost{\mcore\melt}$, $\mval(\melt)$ and $\knowInv\iname\prop$ are persistent.
 Persistence is preserved by conjunction, disjunction, separating conjunction as well as universal and existential quantification.
 
 In our proofs, we will implicitly add and remove $\always$ from persistent assertions as necessary, and generally treat them like normal, non-linear assumptions.

docs/logic.tex

@@ -305,6 +305,7 @@ In writing $\vctx, x:\type$, we presuppose that $x$ is not already declared in $
 \end{mathparpagebreakable}
 
 \subsection{Proof rules}
+\label{sec:proof-rules}
 
 The judgment $\vctx \mid \pfctx \proves \prop$ says that with free variables $\vctx$, proposition $\prop$ holds whenever all assumptions $\pfctx$ hold.
 We implicitly assume that an arbitrary variable context, $\vctx$, is added to every constituent of the rules.
@@ -516,6 +517,8 @@ This is entirely standard.
 { \knowInv\iname\prop \proves \always \knowInv\iname\prop}
 \and
 { \ownGGhost{\mcore\melt} \proves \always \ownGGhost{\mcore\melt}}
+\and
+{ \mval(\melt) \proves \always \mval(\melt)}
 \end{mathpar}
 
 \paragraph{Laws of primitive view shifts.}