The Hölder condition for a function on an arc
in the complex plane requires
that
for all , with fixed positive real numbers
and
.
In some literature, functions satisfying the Hölder condition are said to be
-Hölder continuous
on
.
The quantities
and
are sometimes called the Hölder exponent and Hölder
constant of
, respectively.
The Hölder condition comes up frequently in several branches of mathematics, notable among which is the study of Brownian motion in probability.