01122nas a2200145   4500008004100000245005400041210005100095260001300146520066000159653006000819100002500879700001600904700002000920856003600940       2014                        en  d00aOn conjugate times of LQ optimal control problems0 aconjugate times of LQ optimal control problems  bSpringer3 aMotivated by the study of linear quadratic optimal control problems, we
consider a dynamical system with a constant, quadratic Hamiltonian, and we
characterize the number of conjugate times in terms of the spectrum of the
Hamiltonian vector field $\vec{H}$. We prove the following dichotomy: the
number of conjugate times is identically zero or grows to infinity. The latter
case occurs if and only if $\vec{H}$ has at least one Jordan block of odd
dimension corresponding to a purely imaginary eigenvalue. As a byproduct, we
obtain bounds from below on the number of conjugate times contained in an
interval in terms of the spectrum of $\vec{H}$.10aOptimal control, Lagrange Grassmannian, Conjugate point1 aAgrachev, Andrei, A.1 aRizzi, Luca1 aSilveira, Pavel  uhttp://hdl.handle.net/1963/7227