<s>
Ariane	B-Language
flight	I-Language
V88	I-Language
was	O
the	O
failed	O
maiden	O
flight	O
of	O
the	O
Arianespace	O
Ariane	O
5	O
rocket	O
,	O
vehicle	O
no	O
.	O
</s>
<s>
The	O
launch	O
ended	O
in	O
failure	O
due	O
to	O
multiple	O
errors	O
in	O
the	O
software	O
design	O
:	O
dead	B-Application
code	I-Application
,	O
intended	O
only	O
for	O
Ariane	O
4	O
,	O
with	O
inadequate	O
protection	O
against	O
integer	B-Error_Name
overflow	I-Error_Name
led	O
to	O
an	O
exception	B-General_Concept
handled	I-General_Concept
inappropriately	O
,	O
halting	O
the	O
whole	O
otherwise	O
unaffected	O
inertial	O
navigation	O
system	O
.	O
</s>
<s>
The	O
failure	O
has	O
become	O
known	O
as	O
one	O
of	O
the	O
most	O
infamous	O
and	O
expensive	O
software	B-Error_Name
bugs	I-Error_Name
in	O
history	O
.	O
</s>
<s>
The	O
greater	O
values	O
of	O
BH	O
caused	O
a	O
data	O
conversion	O
from	O
a	O
64-bit	O
floating	B-Algorithm
point	I-Algorithm
number	I-Algorithm
to	O
a	O
16-bit	O
signed	B-Algorithm
integer	O
value	O
to	O
overflow	B-Algorithm
and	O
cause	O
a	O
hardware	B-General_Concept
exception	I-General_Concept
.	O
</s>
<s>
The	O
programmers	O
had	O
protected	O
only	O
four	O
out	O
of	O
seven	O
critical	O
variables	O
against	O
overflow	B-Algorithm
to	O
keep	O
within	O
a	O
required	O
maximum	O
workload	O
target	O
of	O
80%	O
for	O
the	O
on-board	O
Inertial	O
Reference	O
System	O
computer	O
,	O
and	O
relied	O
on	O
assumptions	O
which	O
were	O
correct	O
for	O
the	O
Ariane4	O
,	O
but	O
not	O
Ariane5	O
,	O
trajectory	O
about	O
the	O
possible	O
range	O
of	O
values	O
for	O
the	O
three	O
unprotected	O
variables	O
.	O
</s>
<s>
The	O
exception	O
halted	O
both	O
of	O
the	O
inertial	O
reference	O
system	O
modules	O
,	O
although	O
they	O
were	O
intended	O
to	O
be	O
redundant	B-Error_Name
.	O
</s>
<s>
The	O
official	O
report	O
on	O
the	O
crash	O
(	O
conducted	O
by	O
an	O
inquiry	O
board	O
headed	O
by	O
Jacques-Louis	O
Lions	O
)	O
noted	O
that	O
"	O
An	O
underlying	O
theme	O
in	O
the	O
development	O
of	O
Ariane5	O
is	O
the	O
bias	O
towards	O
the	O
mitigation	B-General_Concept
of	I-General_Concept
random	I-General_Concept
failure	I-General_Concept
.	O
</s>
<s>
The	O
launch	O
failure	O
brought	O
the	O
high	O
risks	O
associated	O
with	O
complex	O
computing	O
systems	O
to	O
the	O
attention	O
of	O
the	O
general	O
public	O
,	O
politicians	O
,	O
and	O
executives	O
,	O
resulting	O
in	O
increased	O
support	O
for	O
research	O
on	O
ensuring	O
the	O
reliability	O
of	O
safety-critical	B-Application
systems	I-Application
.	O
</s>
<s>
The	O
subsequent	O
automated	O
analysis	O
of	O
the	O
Ariane	O
code	O
(	O
written	O
in	O
Ada	B-Language
)	O
was	O
the	O
first	O
example	O
of	O
large-scale	O
static	O
code	O
analysis	O
by	O
abstract	O
interpretation	O
.	O
</s>
