Pansu derivative
In mathematics, the Pansu derivative is a derivative on a Carnot group, introduced by . A Carnot group  admits a one-parameter family of dilations, . If  and  are Carnot groups, then the Pansu derivative of a function  at a point  is the function  defined by

provided that this limit exists. A key theorem in this area is the Pansu–Rademacher theorem, a generalization of Rademacher's theorem, which can be stated as follows: Lipschitz continuous functions between (measurable subsets of) Carnot groups are Pansu differentiable almost everywhere. References

Lie groups