Corollary 5.9.
deg
(
n
ϕ
)
=
n
2
deg
(
ϕ
)
for all
n
∈
ℤ
,
ϕ
∈
Hom
(
E
1
,
E
2
)
. In particular,
deg
[
n
]
=
n
2
.