Definition.
For
ϕ
,
ψ
∈
End
(
E
)
=
Hom
(
E
,
E
)
, we put
⟨
ϕ
,
ψ
⟩
=
deg
(
ϕ
+
ψ
)
−
deg
ϕ
−
deg
ψ
and
tr
(
ϕ
)
=
⟨
ϕ
,
1
⟩
.