  In this work we develop the mathematical framework of !FTL, a new gesture
recognition algorithm and we prove its convergence. Such convergence suggests
to adopt a notion of shape for smooth gestures as a complex valued function.
However, the idea inspiring that notion came to us from Clifford numbers and
not from complex numbers. Moreover, the Clifford vector algebra can be used to
extend to higher dimensions the notion of shape of a gesture, while complex
numbers are useless to that purpose.
