Commit 7696a7c1 authored by Robbert Krebbers's avatar Robbert Krebbers

Use \nat macro.

parent 68aead2a
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......@@ -6,11 +6,11 @@ The model of Iris lives in the category of \emph{Complete Ordered Families of Eq
This definition varies slightly from the original one in~\cite{catlogic}.
\begin{defn}[Chain]
Given some set $\cofe$ and an indexed family $({\nequiv{n}} \subseteq \cofe \times \cofe)_{n \in \mathbb{N}}$ of equivalence relations, a \emph{chain} is a function $c : \mathbb{N} \to \cofe$ such that $\All n, m. n \leq m \Ra c (m) \nequiv{n} c (n)$.
Given some set $\cofe$ and an indexed family $({\nequiv{n}} \subseteq \cofe \times \cofe)_{n \in \nat}$ of equivalence relations, a \emph{chain} is a function $c : \nat \to \cofe$ such that $\All n, m. n \leq m \Ra c (m) \nequiv{n} c (n)$.
\end{defn}
\begin{defn}
A \emph{complete ordered family of equivalences} (COFE) is a tuple $(\cofe, ({\nequiv{n}} \subseteq \cofe \times \cofe)_{n \in \mathbb{N}}, \lim : \chain(\cofe) \to \cofe)$ satisfying
A \emph{complete ordered family of equivalences} (COFE) is a tuple $(\cofe, ({\nequiv{n}} \subseteq \cofe \times \cofe)_{n \in \nat}, \lim : \chain(\cofe) \to \cofe)$ satisfying
\begin{align*}
\All n. (\nequiv{n}) ~& \text{is an equivalence relation} \tagH{cofe-equiv} \\
\All n, m.& n \geq m \Ra (\nequiv{n}) \subseteq (\nequiv{m}) \tagH{cofe-mono} \\
......@@ -115,7 +115,7 @@ Since Iris ensures that the global ghost state is valid, this means that we can
\subsection{CMRA}
\begin{defn}
A \emph{CMRA} is a tuple $(\monoid : \COFEs, (\mval_n \subseteq \monoid)_{n \in \mathbb{N}},\\ \mcore{{-}}: \monoid \nfn \maybe\monoid, (\mtimes) : \monoid \times \monoid \nfn \monoid)$ satisfying:
A \emph{CMRA} is a tuple $(\monoid : \COFEs, (\mval_n \subseteq \monoid)_{n \in \nat},\\ \mcore{{-}}: \monoid \nfn \maybe\monoid, (\mtimes) : \monoid \times \monoid \nfn \monoid)$ satisfying:
\begin{align*}
\All n, \melt, \meltB.& \melt \nequiv{n} \meltB \land \melt\in\mval_n \Ra \meltB\in\mval_n \tagH{cmra-valid-ne} \\
\All n, m.& n \geq m \Ra \mval_n \subseteq \mval_m \tagH{cmra-valid-mono} \\
......@@ -136,7 +136,7 @@ Since Iris ensures that the global ghost state is valid, this means that we can
This is a natural generalization of RAs over COFEs.
All operations have to be non-expansive, and the validity predicate $\mval$ can now also depend on the step-index.
We define the plain $\mval$ as the ``limit'' of the $\mval_n$:
\[ \mval \eqdef \bigcap_{n \in \mathbb{N}} \mval_n \]
\[ \mval \eqdef \bigcap_{n \in \nat} \mval_n \]
\paragraph{The extension axiom (\ruleref{cmra-extend}).}
Notice that the existential quantification in this axiom is \emph{constructive}, \ie it is a sigma type in Coq.
......
......@@ -16,7 +16,7 @@ $\latert(-)$ is a locally \emph{contractive} functor from $\COFEs$ to $\COFEs$.
Given a CMRA $\monoid$, we define the COFE $\UPred(\monoid)$ of \emph{uniform predicates} over $\monoid$ as follows:
\begin{align*}
\UPred(\monoid) \eqdef{} \setComp{\pred: \mathbb{N} \times \monoid \to \mProp}{
\UPred(\monoid) \eqdef{} \setComp{\pred: \nat \times \monoid \to \mProp}{
\begin{inbox}[c]
(\All n, x, y. \pred(n, x) \land x \nequiv{n} y \Ra \pred(n, y)) \land {}\\
(\All n, m, x, y. \pred(n, x) \land x \mincl y \land m \leq n \land y \in \mval_m \Ra \pred(m, y))
......@@ -29,8 +29,8 @@ $\UPred(-)$ is a locally non-expansive functor from $\CMRAs$ to $\COFEs$.
One way to understand this definition is to re-write it a little.
We start by defining the COFE of \emph{step-indexed propositions}: For every step-index, the proposition either holds or does not hold.
\begin{align*}
\SProp \eqdef{}& \psetdown{\mathbb{N}} \\
\eqdef{}& \setComp{X \in \pset{\mathbb{N}}}{ \All n, m. n \geq m \Ra n \in X \Ra m \in X } \\
\SProp \eqdef{}& \psetdown{\nat} \\
\eqdef{}& \setComp{X \in \pset{\nat}}{ \All n, m. n \geq m \Ra n \in X \Ra m \in X } \\
X \nequiv{n} Y \eqdef{}& \All m \leq n. m \in X \Lra m \in Y
\end{align*}
Notice that this notion of $\SProp$ is already hidden in the validity predicate $\mval_n$ of a CMRA:
......@@ -114,7 +114,7 @@ $K \fpfn (-)$ is a locally non-expansive functor from $\CMRAs$ to $\CMRAs$.
Given some COFE $\cofe$, we define $\agm(\cofe)$ as follows:
\begin{align*}
\agm(\cofe) \eqdef{}& \set{(c, V) \in (\mathbb{N} \to \cofe) \times \SProp}/\ {\sim} \\[-0.2em]
\agm(\cofe) \eqdef{}& \set{(c, V) \in (\nat \to \cofe) \times \SProp}/\ {\sim} \\[-0.2em]
\textnormal{where }& \melt \sim \meltB \eqdef{} \melt.V = \meltB.V \land
\All n. n \in \melt.V \Ra \melt.c(n) \nequiv{n} \meltB.c(n) \\
% \All n \in {\melt.V}.\, \melt.x \nequiv{n} \meltB.x \\
......@@ -131,11 +131,11 @@ You can think of the $c$ as a \emph{chain} of elements of $\cofe$ that has to co
The reason we store a chain, rather than a single element, is that $\agm(\cofe)$ needs to be a COFE itself, so we need to be able to give a limit for every chain of $\agm(\cofe)$.
However, given such a chain, we cannot constructively define its limit: Clearly, the $V$ of the limit is the limit of the $V$ of the chain.
But what to pick for the actual data, for the element of $\cofe$?
Only if $V = \mathbb{N}$ we have a chain of $\cofe$ that we can take a limit of; if the $V$ is smaller, the chain ``cancels'', \ie stops converging as we reach indices $n \notin V$.
Only if $V = \nat$ we have a chain of $\cofe$ that we can take a limit of; if the $V$ is smaller, the chain ``cancels'', \ie stops converging as we reach indices $n \notin V$.
To mitigate this, we apply the usual construction to close a set; we go from elements of $\cofe$ to chains of $\cofe$.
We define an injection $\aginj$ into $\agm(\cofe)$ as follows:
\[ \aginj(x) \eqdef \record{\mathrm c \eqdef \Lam \any. x, \mathrm V \eqdef \mathbb{N}} \]
\[ \aginj(x) \eqdef \record{\mathrm c \eqdef \Lam \any. x, \mathrm V \eqdef \nat} \]
There are no interesting frame-preserving updates for $\agm(\cofe)$, but we can show the following:
\begin{mathpar}
\axiomH{ag-val}{\aginj(x) \in \mval_n}
......
......@@ -156,7 +156,7 @@ To instantiate the DC logic (base logic with dynamic composeable resources), the
From this, we construct the bifunctor defining the overall resources as follows:
\begin{align*}
\textdom{ResF}(\cofe^\op, \cofe) \eqdef{}& \prod_{i \in \mathcal I} \mathbb{N} \fpfn \iFunc_i(\cofe^\op, \cofe)
\textdom{ResF}(\cofe^\op, \cofe) \eqdef{}& \prod_{i \in \mathcal I} \nat \fpfn \iFunc_i(\cofe^\op, \cofe)
\end{align*}
(We will motivate both the use of a product and the finite partial function below.)
$\textdom{ResF}(\cofe^\op, \cofe)$ is a CMRA by lifting the individual CMRAs pointwise, and it has a unit (using the empty finite partial functions).
......
......@@ -33,7 +33,7 @@ We are thus going to define the assertions as mapping CMRA elements to sets of s
\Sem{\vctx \proves t =_\type u : \Prop}_\gamma &\eqdef
\Lam \any. \setComp{n}{\Sem{\vctx \proves t : \type}_\gamma \nequiv{n} \Sem{\vctx \proves u : \type}_\gamma} \\
\Sem{\vctx \proves \FALSE : \Prop}_\gamma &\eqdef \Lam \any. \emptyset \\
\Sem{\vctx \proves \TRUE : \Prop}_\gamma &\eqdef \Lam \any. \mathbb{N} \\
\Sem{\vctx \proves \TRUE : \Prop}_\gamma &\eqdef \Lam \any. \nat \\
\Sem{\vctx \proves \prop \land \propB : \Prop}_\gamma &\eqdef
\Lam \melt. \Sem{\vctx \proves \prop : \Prop}_\gamma(\melt) \cap \Sem{\vctx \proves \propB : \Prop}_\gamma(\melt) \\
\Sem{\vctx \proves \prop \lor \propB : \Prop}_\gamma &\eqdef
......@@ -101,7 +101,7 @@ We can now define \emph{semantic} logical entailment.
\Sem{\vctx \mid \prop \proves \propB} \eqdef
\begin{aligned}[t]
\MoveEqLeft
\forall n \in \mathbb{N}.\;
\forall n \in \nat.\;
\forall \rs \in \textdom{Res}.\;
\forall \gamma \in \Sem{\vctx},\;
\\&
......
......@@ -15,9 +15,9 @@ To this end, we use tokens that manage which invariants are currently enabled.
We assume to have the following four CMRAs available:
\begin{align*}
\textmon{State} \eqdef{}& \authm(\exm(\State)) \\
\textmon{Inv} \eqdef{}& \authm(\mathbb N \fpfn \agm(\latert \iPreProp)) \\
\textmon{En} \eqdef{}& \pset{\mathbb N} \\
\textmon{Dis} \eqdef{}& \finpset{\mathbb N}
\textmon{Inv} \eqdef{}& \authm(\nat \fpfn \agm(\latert \iPreProp)) \\
\textmon{En} \eqdef{}& \pset{\nat} \\
\textmon{Dis} \eqdef{}& \finpset{\nat}
\end{align*}
The last two are the tokens used for managing invariants, $\textmon{Inv}$ is the monoid used to manage the invariants themselves.
Finally, $\textmon{State}$ is used to provide the program with a view of the physical state of the machine.
......@@ -28,7 +28,7 @@ Furthermore, we assume that instances named $\gname_{\textmon{State}}$, $\gname_
\paragraph{World Satisfaction.}
We can now define the assertion $W$ (\emph{world satisfaction}) which ensures that the enabled invariants are actually maintained:
\begin{align*}
W \eqdef{}& \Exists I : \mathbb N \fpfn \Prop.
W \eqdef{}& \Exists I : \nat \fpfn \Prop.
\begin{array}{@{} l}
\ownGhost{\gname_{\textmon{Inv}}}{\authfull
\mapsingletonComp {\iname}
......@@ -47,7 +47,7 @@ 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, $\mathbb N$, and $\bot$ for the smallest possible mask $\emptyset$.
We use $\top$ as symbol for the largest possible mask, $\nat$, and $\bot$ for the smallest possible mask $\emptyset$.
We will write $\pvs[\mask] \prop$ for $\pvs[\mask][\mask]\prop$.
%
View updates satisfy the following basic proof rules:
......@@ -369,14 +369,14 @@ Furthermore, we will often know that namespaces are \emph{disjoint} just by look
The namespaces $\namesp.\texttt{iris}$ and $\namesp.\texttt{gps}$ are disjoint no matter the choice of $\namesp$.
As a result, there is often no need to track disjointness of namespaces, we just have to pick the namespaces that we allocate our invariants in accordingly.
Formally speaking, let $\namesp \in \textlog{InvNamesp} \eqdef \List(\mathbb N)$ be the type of \emph{invariant namespaces}.
Formally speaking, let $\namesp \in \textlog{InvNamesp} \eqdef \List(\nat)$ be the type of \emph{invariant namespaces}.
We use the notation $\namesp.\iname$ for the namespace $[\iname] \dplus \namesp$.
(In other words, the list is ``backwards''. This is because cons-ing to the list, like the dot does above, is easier to deal with in Coq than appending at the end.)
The elements of a namespaces are \emph{structured invariant names} (think: Java fully qualified class name).
They, too, are lists of $\mathbb N$, the same type as namespaces.
In order to connect this up to the definitions of \Sref{sec:invariants}, we need a way to map structued invariant names to $\mathbb N$, the type of ``plain'' invariant names.
Any injective mapping $\textlog{namesp\_inj}$ will do; and such a mapping has to exist because $\List(\mathbb N)$ is countable.
They, too, are lists of $\nat$, the same type as namespaces.
In order to connect this up to the definitions of \Sref{sec:invariants}, we need a way to map structued invariant names to $\nat$, the type of ``plain'' invariant names.
Any injective mapping $\textlog{namesp\_inj}$ will do; and such a mapping has to exist because $\List(\nat)$ is countable.
Whenever needed, we (usually implicitly) coerce $\namesp$ to its encoded suffix-closure, \ie to the set of encoded structured invariant names contained in the namespace: \[\namecl\namesp \eqdef \setComp{\iname}{\Exists \namesp'. \iname = \textlog{namesp\_inj}(\namesp' \dplus \namesp)}\]
We will overload the notation for invariant assertions for using namespaces instead of names:
......
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