%0 Journal Article %T Bang--bang trajectories with a double switching time: sufficient strong local optimality conditions %A Laura Poggiolini %A Marco Spadini %J Mathematics %D 2010 %I arXiv %X This paper gives sufficient conditions for a class of bang-bang extremals with multiple switches to be locally optimal in the strong topology. The conditions are the natural generalizations of the ones considered in previous papers for more specific cases. We require both the strict bang-bang Legendre condition, and the second order conditions for the finite dimensional problem obtained by moving the switching times of the reference trajectory. %U http://arxiv.org/abs/1010.1149v2