<s>
If	O
K	O
is	O
an	O
invariant	O
subspace	O
for	O
T	O
,	O
then	O
the	O
compression	B-Algorithm
of	O
T	O
to	O
K	O
is	O
the	O
restricted	O
operator	O
K	O
→	O
K	O
sending	O
k	O
to	O
Tk	O
.	O
</s>
<s>
where	O
is	O
the	O
adjoint	O
of	O
V	O
.	O
If	O
T	O
is	O
a	O
self-adjoint	O
operator	O
,	O
then	O
the	O
compression	B-Algorithm
is	O
also	O
self-adjoint	O
.	O
</s>
<s>
When	O
V	O
is	O
replaced	O
by	O
the	O
inclusion	B-Algorithm
map	I-Algorithm
,	O
,	O
and	O
we	O
acquire	O
the	O
special	O
definition	O
above	O
.	O
</s>
