<s>
In	O
functional	B-Application
analysis	I-Application
,	O
compact	O
operators	O
are	O
linear	O
operators	O
on	O
Banach	O
spaces	O
that	O
map	O
bounded	O
sets	O
to	O
relatively	O
compact	O
sets	O
.	O
</s>
<s>
The	O
spectral	B-Algorithm
theory	I-Algorithm
of	I-Algorithm
compact	I-Algorithm
operators	I-Algorithm
was	O
first	O
developed	O
by	O
F	O
.	O
Riesz	O
.	O
</s>
<s>
The	O
E(λ )	O
satisfy	O
E(λ )	O
2	O
=	O
E(λ )	O
,	O
so	O
that	O
they	O
are	O
indeed	O
projection	B-Algorithm
operators	I-Algorithm
or	O
spectral	O
projections	B-Algorithm
.	O
</s>
