Lemma 13.5.
Assuming that:
ϕ
:
E
→
E
′
an
isogeny
defined over
ℚ
Then
ĥ
ĥ
ĥ
(
ϕ
P
)
=
(
deg
ϕ
)
ĥ
(
P
)
∀
P
∈
E
(
ℚ
)
.