Let be an elliptic curve over a number field
,
or a nonconstant elliptic surface
(elliptic curve over a function field
),
and
a point of nonzero canonical height
on
.
Let
be
in the former case, and the discriminant degree
of
in the latter. Lang conjectured that there exists a constant
such that
.
Hindry and Silverman proved this under the ABC conjecture for
; in particular they proved it unconditionally for an elliptic surface.
The constant
obtained by Hindry and Silverman, though explicit,
is very small - less than
-
but is essentially the best that the analysis of Hindry and Silverman can
yield. We review this analysis and give two improvements that together
improve
to about
.
We also explain how the same ideas lead to the conjecture that
the correct value is
(approximately
),
and compare this with numerical data for explicit
with
low
in the cases
and
.