Let 
be a Hilbert space, 
the set of bounded linear operators
from 
to itself, 
an operator on 
, and 
the operator spectrum
of 
.
Then if 
and 
is normal, there exists a unique resolution of the identity 
on the Borel subsets of 
which satisfies
 |
Furthermore, every projection 
commutes with every
that commutes
with 
.
