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Ivancevic_Applied-Diff-Geom

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388 <strong>Applied</strong> <strong>Diff</strong>erential <strong>Geom</strong>etry: A Modern IntroductionbyL x i ≡ ∂ x iL, and Lẋi ≡ ∂ẋiL.A variational problem (I, ω; ϕ) is said to be strongly non–degenerate,or well–posed [Griffiths (1983)], if the determinant of the matrix of mixedvelocity partials of the Lagrangian is positive definite, i.e.,det ‖Lẋiẋ j ‖ > 0.The extended Pfaffian system⎧⎨⎩θ i = 0dLẋi − L x i ω = 0ω ≠ 0.generates classical Euler–Lagrangian equationsddt L ẋ i = L xi, (3.197)describing the control–free, dissipation–free, conservative skeleton dynamics.If an integral manifold N satisfies the Euler–Lagrangian equations(3.197) of a well–posed variational problem on X thenddt(∫N tϕfor any admissible variation N t ∈ N that satisfies the endpoint conditionsω = θ i = 0.Theorem: Under the above conditions, both the Lagrangian dynamicswith initial conditions{ddt L ẋ i = L x ix(t 0 ) = x 0 , ẋ(t 0 ) = ẋ 0)t=0= 0and the Lagrangian dynamics with endpoint conditions{ddt L ẋ i = L x ix(t 0 ) = x 0 , x(t 1 ) = x 1have unique solutions. For the proof, see [Griffiths (1983)].Now, if M is a smooth Riemannian manifold, its metric g =< . > islocally given by a positive definite quadratic formds 2 = g ij (x) dx i dx j , (3.198)

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