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 
.
