<s>
concurrent	B-Architecture
programs	I-Architecture
with	O
shared	O
variables	O
.	O
</s>
<s>
extended	O
this	O
work	O
to	O
apply	O
to	O
concurrent	B-Architecture
programs	I-Architecture
.	O
</s>
<s>
developing	O
concurrent	B-Architecture
programs	I-Architecture
with	O
shared	O
variables	O
and	O
proving	O
them	O
correct	O
.	O
</s>
<s>
Now	O
consider	O
concurrent	B-Architecture
programming	I-Architecture
with	O
shared	O
variables	O
.	O
</s>
<s>
advisor	O
David	O
Gries	O
,	O
Susan	O
Owicki	O
developed	O
the	O
notion	O
of	O
interference	B-Application
freedom	I-Application
.	O
</s>
<s>
If	O
processes	O
and	O
satisfy	O
interference	B-Application
freedom	I-Application
,	O
then	O
their	O
parallel	O
execution	O
will	O
work	O
as	O
planned	O
.	O
</s>
<s>
Hoare	O
alluded	O
to	O
proof	O
outlines	O
in	O
his	O
early	O
work	O
;	O
for	O
interference	B-Application
freedom	I-Application
,	O
it	O
had	O
to	O
be	O
formalized	O
.	O
</s>
<s>
Two	O
statements	O
were	O
introduced	O
to	O
deal	O
with	O
concurrency	B-Architecture
.	O
</s>
<s>
including	O
freedom	O
from	O
deadlock	B-Operating_System
,	O
program	O
termination	O
,	O
and	O
mutual	O
exclusion	O
.	O
</s>
<s>
Owicki-Gries	O
provides	O
conditions	O
under	O
which	O
deadlock	B-Operating_System
cannot	O
occur	O
.	O
</s>
<s>
Apt	O
et	O
al	O
show	O
that	O
this	O
new	O
inference	O
rule	O
does	O
not	O
satisfy	O
interference	B-Application
freedom	I-Application
.	O
</s>
<s>
The	O
solution	O
in	O
Owicki-Gries	O
,	O
complete	O
with	O
program	O
,	O
proof	O
outline	O
,	O
and	O
discussion	O
of	O
interference	B-Application
freedom	I-Application
,	O
takes	O
less	O
than	O
two	O
pages	O
.	O
</s>
<s>
Interference	B-Application
freedom	I-Application
is	O
quite	O
easy	O
to	O
check	O
,	O
since	O
there	O
is	O
only	O
one	O
shared	O
variable	O
.	O
</s>
<s>
Gries	O
felt	O
that	O
interference	B-Application
freedom	I-Application
could	O
be	O
used	O
to	O
prove	O
the	O
on-the-fly	O
garbage	O
collector	O
correct	O
.	O
</s>
<s>
The	O
image	O
below	O
,	O
by	O
Ilya	O
Sergey	O
,	O
depicts	O
the	O
flow	O
of	O
ideas	O
that	O
have	O
been	O
implemented	O
in	O
logics	O
that	O
deal	O
with	O
concurrency	B-Architecture
.	O
</s>
<s>
At	O
the	O
root	O
is	O
interference	B-Application
freedom	I-Application
.	O
</s>
<s>
Interference	B-Application
freedom	I-Application
is	O
not	O
compositional	O
.	O
</s>
<s>
Xu	O
et	O
al	O
observe	O
that	O
Rely-Guarantee	O
is	O
a	O
reformulation	O
of	O
interference	B-Application
freedom	I-Application
;	O
revealing	O
the	O
connection	O
between	O
these	O
two	O
methods	O
,	O
they	O
say	O
,	O
offers	O
a	O
deep	O
understanding	O
about	O
verification	O
of	O
shared	O
variable	O
programs	O
.	O
</s>
<s>
Deriving	O
concurrent	B-Architecture
programs	I-Architecture
.	O
</s>
<s>
Feijen	O
and	O
van	O
Gasteren	O
show	O
how	O
to	O
use	O
Owicki-Gries	O
to	O
design	O
concurrent	B-Architecture
programs	I-Architecture
,	O
but	O
the	O
lack	O
of	O
a	O
theory	O
of	O
progress	O
means	O
that	O
designs	O
are	O
driven	O
only	O
by	O
safety	B-Application
requirements	I-Application
.	O
</s>
<s>
Dongol	O
,	O
Goldson	O
,	O
Mooij	O
,	O
and	O
Hayes	O
have	O
extended	O
this	O
work	O
to	O
include	O
a	O
"	O
logic	O
of	O
progress	O
"	O
based	O
on	O
Chandy	O
and	O
Misra	O
's	O
language	O
Unity	B-Language
,	O
molded	O
to	O
fit	O
a	O
sequential	B-Architecture
programming	I-Architecture
model	O
.	O
</s>
<s>
Goldson	O
and	O
Dongol	O
show	O
how	O
this	O
logic	O
is	O
used	O
to	O
improve	O
the	O
process	O
of	O
designing	O
programs	O
,	O
using	O
Dekker	B-Operating_System
's	I-Operating_System
algorithm	I-Operating_System
for	O
two	O
processes	O
as	O
an	O
example	O
.	O
</s>
<s>
Dongol	O
and	O
Mooij	O
present	O
more	O
techniques	O
for	O
deriving	O
programs	O
,	O
using	O
Peterson	B-Operating_System
's	I-Operating_System
mutual	I-Operating_System
exclusion	I-Operating_System
algorithm	I-Operating_System
as	O
one	O
example	O
.	O
</s>
<s>
Dongol	O
and	O
Mooij	O
show	O
how	O
to	O
reduce	O
the	O
calculational	O
overhead	O
in	O
formal	O
proofs	O
and	O
derivations	O
and	O
derive	O
Dekker	B-Operating_System
's	I-Operating_System
algorithm	I-Operating_System
again	O
,	O
leading	O
to	O
some	O
new	O
and	O
simpler	O
variants	O
of	O
the	O
algorithm	O
.	O
</s>
<s>
Mooij	O
studies	O
calculational	O
rules	O
for	O
Unity	B-Language
's	O
leads-to	O
relation	O
.	O
</s>
<s>
Lahav	O
and	O
Vafeiadis	O
strengthen	O
the	O
interference	B-Application
freedom	I-Application
check	O
to	O
produce	O
(	O
we	O
quote	O
from	O
the	O
abstract	O
)	O
"	O
OGRA	O
,	O
a	O
program	O
logic	O
that	O
is	O
sound	O
for	O
reasoning	O
about	O
programs	O
in	O
the	O
release-acquire	O
fragment	O
of	O
the	O
C11	O
memory	O
model.	O
"	O
</s>
<s>
Quantum	B-Device
programming	I-Device
.	O
</s>
<s>
Ying	O
et	O
al	O
extend	O
interference	B-Application
freedom	I-Application
to	O
quantum	B-Device
programming	I-Device
.	O
</s>
<s>
Van	O
Gasteren	O
and	O
Feijen	O
discuss	O
the	O
formal	O
development	O
of	O
concurrent	B-Architecture
programs	I-Architecture
entirely	O
on	O
the	O
idea	O
of	O
interference	B-Application
freedom	I-Application
.	O
</s>
<s>
Schneider	O
uses	O
interference	B-Application
freedom	I-Application
as	O
the	O
main	O
tool	O
in	O
developing	O
and	O
proving	O
concurrent	B-Architecture
programs	I-Architecture
.	O
</s>
<s>
A	O
connection	O
to	O
temporal	O
logic	O
is	O
given	O
,	O
so	O
arbitrary	O
safety	B-Application
and	I-Application
liveness	I-Application
properties	I-Application
can	O
be	O
proven	O
.	O
</s>
<s>
Verification	O
of	O
Sequential	O
and	O
Concurrent	B-Architecture
Programs	I-Architecture
,	O
1991	O
,	O
2009	O
.	O
</s>
<s>
This	O
first	O
text	O
to	O
cover	O
verification	O
of	O
structured	O
concurrent	B-Architecture
programs	I-Architecture
,	O
by	O
Apt	O
et	O
al	O
,	O
has	O
gone	O
through	O
several	O
editions	O
over	O
several	O
decades	O
.	O
</s>
<s>
Concurrency	B-Architecture
Verification	O
:	O
Introduction	O
to	O
Compositional	O
and	O
Non-Compositional	O
Methods	O
,	O
2112	O
.	O
</s>
<s>
1999	O
:	O
Nipkow	O
and	O
Nieto	O
present	O
the	O
first	O
formalization	O
of	O
interference	B-Application
freedom	I-Application
and	O
its	O
compositional	O
version	O
,	O
the	O
rely-guarantee	O
method	O
,	O
in	O
a	O
theorem	O
prover	O
:	O
Isabelle/HOL	O
.	O
</s>
<s>
2017	O
:	O
Denissen	O
reports	O
on	O
an	O
implementation	O
of	O
Owicki-Gries	O
in	O
the	O
"	O
verification	O
ready	O
"	O
programming	O
language	O
Dafny	B-Application
.	O
</s>
<s>
Denissen	O
remarks	O
on	O
the	O
ease	O
of	O
use	O
of	O
Dafny	B-Application
and	O
his	O
extension	O
to	O
it	O
,	O
making	O
it	O
extremely	O
suitable	O
when	O
teaching	O
students	O
about	O
interference	B-Application
freedom	I-Application
.	O
</s>
<s>
He	O
lists	O
some	O
twenty	O
institutions	O
that	O
teach	O
interference	B-Application
freedom	I-Application
.	O
</s>
<s>
2022	O
:	O
This	O
webpage	O
describes	O
the	O
Civl	O
verifier	O
for	O
concurrent	B-Architecture
programs	I-Architecture
and	O
gives	O
instructions	O
for	O
installing	O
it	O
on	O
your	O
computer	O
.	O
</s>
<s>
Kragl	O
et	O
al	O
describe	O
how	O
interference	B-Application
freedom	I-Application
is	O
achieved	O
in	O
Civl	O
using	O
their	O
new	O
specification	O
idiom	O
,	O
yield	O
invariants	O
.	O
</s>
<s>
Civl	O
is	O
the	O
first	O
system	O
that	O
offers	O
refinement	O
reasoning	O
on	O
structured	O
concurrent	B-Architecture
programs	I-Architecture
.	O
</s>
<s>
It	O
is	O
based	O
on	O
the	O
concept	O
of	O
constrained	O
Horn	B-Application
clauses	I-Application
,	O
and	O
it	O
handles	O
programs	O
operating	O
on	O
the	O
heap	O
using	O
a	O
theory	O
of	O
heaps	O
.	O
</s>
<s>
To	O
handle	O
concurrency	B-Architecture
,	O
TRICERA	O
uses	O
a	O
variant	O
of	O
the	O
Owicki-Gries	O
proof	O
rules	O
,	O
with	O
explicit	O
variables	O
to	O
added	O
to	O
represent	O
time	O
and	O
clocks	O
.	O
</s>
