<s>
X10	B-Language
is	O
a	O
programming	O
language	O
being	O
developed	O
by	O
IBM	O
at	O
the	O
Thomas	O
J	O
.	O
Watson	O
Research	O
Center	O
as	O
part	O
of	O
the	O
Productive	O
,	O
Easy-to-use	O
,	O
Reliable	O
Computing	O
System	O
(	O
PERCS	B-Operating_System
)	O
project	O
funded	O
by	O
DARPA	O
's	O
High	O
Productivity	O
Computing	O
Systems	O
(	O
HPCS	O
)	O
program	O
.	O
</s>
<s>
X10	B-Language
is	O
designed	O
specifically	O
for	O
parallel	B-Operating_System
computing	I-Operating_System
using	O
the	O
partitioned	B-Application
global	I-Application
address	I-Application
space	I-Application
(	O
PGAS	O
)	O
model	O
.	O
</s>
<s>
It	O
has	O
a	O
constrained	O
type	O
system	O
for	O
object-oriented	B-Language
programming	I-Language
,	O
a	O
form	O
of	O
dependent	O
types	O
.	O
</s>
<s>
Other	O
features	O
include	O
user-defined	O
primitive	O
struct	O
types	O
;	O
globally	O
distributed	O
arrays	O
,	O
and	O
structured	O
and	O
unstructured	O
parallelism	B-Operating_System
.	O
</s>
<s>
X10	B-Language
uses	O
the	O
concept	O
of	O
parent	O
and	O
child	O
relationships	O
for	O
activities	O
to	O
prevent	O
the	O
lock	O
stalemate	O
that	O
can	O
occur	O
when	O
two	O
or	O
more	O
processes	O
wait	O
for	O
each	O
other	O
to	O
finish	O
before	O
they	O
can	O
complete	O
.	O
</s>
