Proof of equivariance
1 Restriction of symmetries
1.1 New operation 
Symmetries are generated by Hamiltonians of the form:

for arbitrary

.
We want to restrict the possible
to belong to some subspace 
Let us introduce on functions on

the operation

as follows:
1.2 Definition of 
Let us say that a subspace

is
admissible if:
The requirement 3 almost follows from 1 and 2.
The requirement 4 is probably technical, but it is very convenient:
To any

corresponds a symmetry generated by

,
and this correspondence is one-to-one
1.3 Abelian 
The simplest case is when

is abelian,
i.e. when

for any

and

.
In particular, this is the case for theories
coming from BRST formalism.
In this case it is very easy to solve Eq. (
14):
| | (for abelian ) |
| | |
However,
not all abelian
are admissible; we also have to check closedness under

.
2 Proof of 
The proof is based on the following algebraic interpretation of
.
Consider the linear map:
| [space of 1/2-densities on ] |
| | | |
| | | | |
We observe that this map is an intertwiner between:
action of on half-densities in  | and | action of on PDFs on  |
| | |
This is true even when

. In particular, applying this intertwiner to the product

in Eq. (
7):