  We introduce a novel class of rotation invariants of two dimensional curves
based on iterated integrals. The invariants we present are in some sense
complete and we describe an algorithm to calculate them, giving explicit
computations up to order six. We present an application to online
(stroke-trajectory based) character recognition. This seems to be the first
time in the literature that the use of iterated integrals of a curve is
proposed for (invariant) feature extraction in machine learning applications.
