<s>
The	O
cleanroom	B-Application
software	I-Application
engineering	I-Application
process	O
is	O
a	O
software	O
development	O
process	O
intended	O
to	O
produce	O
software	O
with	O
a	O
certifiable	O
level	O
of	O
reliability	O
.	O
</s>
<s>
The	O
cleanroom	B-Application
process	O
was	O
originally	O
developed	O
by	O
Harlan	O
Mills	O
and	O
several	O
of	O
his	O
colleagues	O
including	O
Alan	O
Hevner	O
at	O
IBM	O
.	O
</s>
<s>
The	O
focus	O
of	O
the	O
cleanroom	B-Application
process	O
is	O
on	O
defect	O
prevention	O
,	O
rather	O
than	O
defect	O
removal	O
.	O
</s>
<s>
The	O
name	O
"	O
cleanroom	B-Application
"	O
was	O
chosen	O
to	O
evoke	O
the	O
cleanrooms	B-Application
used	O
in	O
the	O
electronics	O
industry	O
to	O
prevent	O
the	O
introduction	O
of	O
defects	O
during	O
the	O
fabrication	O
of	O
semiconductors	O
.	O
</s>
<s>
The	O
cleanroom	B-Application
process	O
first	O
saw	O
use	O
in	O
the	O
mid	O
to	O
late	O
1980s	O
.	O
</s>
<s>
Recent	O
work	O
on	O
the	O
cleanroom	B-Application
process	O
has	O
examined	O
fusing	O
cleanroom	B-Application
with	O
the	O
automated	O
verification	O
capabilities	O
provided	O
by	O
specifications	O
expressed	O
in	O
CSP	O
.	O
</s>
<s>
Software	O
development	O
based	O
on	O
formal	B-Architecture
methods	I-Architecture
Software	O
tool	O
support	O
based	O
on	O
some	O
mathematical	O
formalism	O
includes	O
model	B-Application
checking	I-Application
,	O
process	O
algebras	O
,	O
and	O
Petri	B-Operating_System
nets	I-Operating_System
.	O
</s>
<s>
Incremental	O
implementation	O
under	O
statistical	O
quality	O
control	O
Cleanroom	B-Application
development	O
uses	O
an	O
iterative	O
approach	O
,	O
in	O
which	O
the	O
product	O
is	O
developed	O
in	O
increments	O
that	O
gradually	O
increase	O
the	O
implemented	O
functionality	O
.	O
</s>
<s>
Statistically	O
sound	O
testing	O
Software	O
testing	O
in	O
the	O
cleanroom	B-Application
process	O
is	O
carried	O
out	O
as	O
a	O
statistical	O
experiment	O
.	O
</s>
