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Jonas Kastberg
iris
Commits
418ca5de
Commit
418ca5de
authored
Oct 29, 2017
by
Ralf Jung
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parent
42dfffc9
Changes
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theories/program_logic/language.v
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418ca5de
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@@ -52,12 +52,19 @@ Section language.
Definition
irreducible
(
e
:
expr
Λ
)
(
σ
:
state
Λ
)
:
=
∀
e'
σ
'
efs
,
¬
prim_step
e
σ
e'
σ
'
efs
.
(* This (weak) form of atomicity is enough to open invariants when WP is safe,
i.e., programs never can get stuck. *)
(* This (weak) form of atomicity is enough to open invariants when WP ensures
safety, i.e., programs never can get stuck. We have an example in
lambdaRust of an expression that is atomic in this sense, but not in the
stronger sense defined below, and we have to be able to open invariants
around that expression. See `CasStuckS` in
[lambdaRust](https://gitlab.mpi-sws.org/FP/LambdaRust-coq/blob/master/theories/lang/lang.v). *)
Definition
atomic
(
e
:
expr
Λ
)
:
Prop
:
=
∀
σ
e'
σ
'
efs
,
prim_step
e
σ
e'
σ
'
efs
→
irreducible
e'
σ
'
.
(* To open invariants with unsafe WP, we need a stronger form of atomicity. *)
(* To open invariants with a WP that does not ensure safety, we need a
stronger form of atomicity. With the above definition, in case `e` reduces
to a stuck non-value, there is no proof that the invariants have been
established again. *)
Definition
strongly_atomic
(
e
:
expr
Λ
)
:
Prop
:
=
∀
σ
e'
σ
'
efs
,
prim_step
e
σ
e'
σ
'
efs
→
is_Some
(
to_val
e'
).
...
...
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