<s>
In	O
cryptography	O
,	O
a	O
distribution	B-General_Concept
ensemble	I-General_Concept
or	O
probability	B-General_Concept
ensemble	I-General_Concept
is	O
a	O
family	O
of	O
distributions	O
or	O
random	O
variables	O
where	O
is	O
a	O
(	O
countable	O
)	O
index	O
set	O
,	O
and	O
each	O
is	O
a	O
random	O
variable	O
,	O
or	O
probability	O
distribution	O
.	O
</s>
<s>
For	O
example	O
,	O
a	O
uniform	B-General_Concept
ensemble	I-General_Concept
is	O
a	O
distribution	B-General_Concept
ensemble	I-General_Concept
where	O
each	O
is	O
uniformly	O
distributed	O
over	O
strings	O
of	O
lengthn	O
.	O
</s>
<s>
In	O
fact	O
,	O
many	O
applications	O
of	O
probability	B-General_Concept
ensembles	I-General_Concept
implicitly	O
assume	O
that	O
the	O
probability	O
spaces	O
for	O
the	O
random	O
variables	O
all	O
coincide	O
in	O
this	O
way	O
,	O
so	O
every	O
probability	B-General_Concept
ensemble	I-General_Concept
is	O
also	O
a	O
stochastic	O
process	O
.	O
</s>
