<s>
In	O
mathematics	O
,	O
the	O
graph	B-Application
of	I-Application
a	I-Application
function	I-Application
is	O
the	O
set	O
of	O
ordered	O
pairs	O
,	O
where	O
In	O
the	O
common	O
case	O
where	O
and	O
are	O
real	O
numbers	O
,	O
these	O
pairs	O
are	O
Cartesian	O
coordinates	O
of	O
points	O
in	O
two-dimensional	O
space	O
and	O
thus	O
form	O
a	O
subset	O
of	O
this	O
plane	O
.	O
</s>
<s>
In	O
the	O
case	O
of	O
functions	O
of	O
two	O
variables	O
,	O
that	O
is	O
functions	O
whose	O
domain	B-Algorithm
consists	O
of	O
pairs	O
the	O
graph	O
usually	O
refers	O
to	O
the	O
set	O
of	O
ordered	O
triples	O
where	O
instead	O
of	O
the	O
pairs	O
as	O
in	O
the	O
definition	O
above	O
.	O
</s>
<s>
A	O
graph	B-Application
of	I-Application
a	I-Application
function	I-Application
is	O
a	O
special	O
case	O
of	O
a	O
relation	B-Algorithm
.	O
</s>
<s>
However	O
,	O
it	O
is	O
often	O
useful	O
to	O
see	O
functions	O
as	O
mappings	B-Algorithm
,	O
which	O
consist	O
not	O
only	O
of	O
the	O
relation	B-Algorithm
between	O
input	O
and	O
output	O
,	O
but	O
also	O
which	O
set	O
is	O
the	O
domain	B-Algorithm
,	O
and	O
which	O
set	O
is	O
the	O
codomain	B-Algorithm
.	O
</s>
<s>
For	O
example	O
,	O
to	O
say	O
that	O
a	O
function	O
is	O
onto	O
(	O
surjective	B-Algorithm
)	O
or	O
not	O
the	O
codomain	B-Algorithm
should	O
be	O
taken	O
into	O
account	O
.	O
</s>
<s>
The	O
graph	B-Application
of	I-Application
a	I-Application
function	I-Application
on	O
its	O
own	O
does	O
n't	O
determine	O
the	O
codomain	B-Algorithm
.	O
</s>
<s>
It	O
is	O
common	O
to	O
use	O
both	O
terms	O
function	O
and	O
graph	B-Application
of	I-Application
a	I-Application
function	I-Application
since	O
even	O
if	O
considered	O
the	O
same	O
object	O
,	O
they	O
indicate	O
viewing	O
it	O
from	O
a	O
different	O
perspective	O
.	O
</s>
<s>
From	O
the	O
graph	O
,	O
the	O
domain	B-Algorithm
is	O
recovered	O
as	O
the	O
set	O
of	O
first	O
component	O
of	O
each	O
pair	O
in	O
the	O
graph	O
.	O
</s>
<s>
Similarly	O
,	O
the	O
range	B-Algorithm
can	O
be	O
recovered	O
as	O
.	O
</s>
<s>
The	O
codomain	B-Algorithm
,	O
however	O
,	O
cannot	O
be	O
determined	O
from	O
the	O
graph	O
alone	O
.	O
</s>
