Title: Cut time in sub-Riemannian problem on Engel group

Authors: A.A. Ardentov, Yu.L. Sachkov

Journal title: ESAIM: COCV

Year: 2015

Abstract:

The left-invariant sub-Riemannian problem on the Engel group is considered. The problem gives the nilpotent approximation to generic rank two sub-Riemannian problems on four-dimensional manifolds.

The global optimality of extremal trajectories is studied via geometric control theory. The global diffeomorphic structure of the exponential mapping is described. As a consequence, the cut time is proved to be equal to the first Maxwell time corresponding to discrete symmetries of the exponential mapping.

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