“…Here, D is a reparametrizationinvariant discrepancy measure between (unparametrized) surfaces. Several versions of this cost function have been introduced, based on representation of surfaces as currents [20], varifolds [7,13] or normal cycles [19]. Assume that S 0 and S 1 are triangulated surfaces and that the cost function D is replaced by a discrete approximation, still denoted D. Then, the optimization problem can be reduced to one tracking explicitly the evolution of the vertices of the triangulation, using the reproducing kernel of V denoted as K. This kernel is a matrix-valued function of two variables x, y ∈ R 3 such that, for all α, y ∈ R 3 , the vector field x → K(x, y)α belongs to V and for all v ∈ V ,…”