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Ivancevic_Applied-Diff-Geom

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<strong>Applied</strong> Manifold <strong>Geom</strong>etry 389where the metric tensor g ij is a C ∞ symmetric matrix g(x) = ‖g ij (x)‖.Kinetic energy of the system Ξ is a function T = T (x, ẋ) on the tangentbundle T M, which induces a positive definite quadratic form in each fibreT x M ⊂ T M. In local coordinates, it is related to the Riemannian metric(3.198) by: T ω 2 = 1 2 ds2 .If potential energy of the system Ξ is a function U = U(x) on M, thenthe autonomous Lagrangian is defined as L(x, ẋ) = T (x, ẋ) − U(x), i.e.,kinetic minus potential energy.The condition of well–posedness is satisfied, asdet ‖Lẋiẋ j ‖ = det ‖g ij(x)‖ > 0.Now, the covariant Euler–Lagrangian equations (3.197) expand asd (gij (x(t)) ẋ j (t) ) = 1 dt2(∂x ig jk (x(t)) ẋ j (t) ẋ k (t) ) − F i (x(t)), (3.199)where F i (x(t)) = ∂U(x(t))∂ẋdenote the gradient force 1–forms.iLetting ∥ g ij (x) ∥ be the inverse matrix to ‖gij (x)‖ and introducing theChristoffel symbolsΓ i jk = g il Γ jkl , Γ jkl = 1 2 (∂ x j g kl + ∂ x kg jl − ∂ x lg jk )the equations (3.199) lead to the classical contravariant form (see [<strong>Ivancevic</strong>(1991); <strong>Ivancevic</strong> and Pearce (2001b); <strong>Ivancevic</strong> and <strong>Ivancevic</strong> (2006)])ẍ i (t) + Γ i jk(x(t)) ẋ j (t) ẋ k (t) = −F i (x(t)), (3.200)where F i (x(t)) = g ij (x) ∂U(x(t))∂ẋdenote the gradient force vector–fields.jThe above Theorem implies that both the Lagrangian dynamics withinitial conditions{ ẍi (t) + Γ i jk (x(t)) ẋj (t) ẋ k (t) = −F i (x(t))(3.201)x(t 0 ) = x 0 , ẋ(t 0 ) = ẋ 0and the Lagrangian dynamics with endpoint conditions{ ẍi (t) + Γ i jk (x(t)) ẋj (t) ẋ k (t) = −F i (x(t))x(t 0 ) = x 0 , x(t 1 ) = x 1(3.202)have unique solutions. We consider the system (3.201) to be the valid basisof human–like dynamics, and the system (3.202) to be the valid basis of thefinite biodynamics control.

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