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Ivancevic_Applied-Diff-Geom

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386 <strong>Applied</strong> <strong>Diff</strong>erential <strong>Geom</strong>etry: A Modern Introductionhomomorphisms. To go directly from • [SO(k) i ] to ∗ •[so(k) ∗ i ] we use thecanonical functor Can [<strong>Ivancevic</strong> and Snoswell (2001); <strong>Ivancevic</strong> (2002);<strong>Ivancevic</strong> and Beagley (2005); <strong>Ivancevic</strong> (2005)]. Therefore we have a commutativetriangle• [SO(k) i ]❅❅❅❅❅❅❘CanLGALie ✠∗•[so(k) i ] ✲∼ • [so(k) ∗ i ]=DualBoth the tangent algebras so(k) i and the cotangent algebras so(k) ∗ i containinfinitesimal group generators, angular velocities ẋ i = ẋ φ i in the firstcase and canonical angular momenta p i = p φi in the second. As Lie groupgenerators, angular velocities and angular momenta satisfy the respectivecommutation relations [ẋ φ i , ẋψ i] = ɛφψθẋ θi and [p φi , p ψi ] = ɛ θ φψ p θ i, wherethe structure constants ɛ φψθand ɛ θ φψconstitute totally antisymmetric third–order tensors.In this way, the functor Dual G : Lie ∼ = Can establishes a geometricalduality between kinematics of angular velocities ẋ i (involved in Lagrangianformalism on the tangent bundle of M) and that of angular momenta p i(involved in Hamiltonian formalism on the cotangent bundle of M). Thisis analyzed below. In other words, we have two functors Lie and Canfrom a category of Lie groups (of which • [SO(k) i ] is a subcategory) into acategory of their Lie algebras (of which • [so(k) i ] and ∗ •[so(k) ∗ i ] are subcategories),and a natural equivalence (functor isomorphism) between themdefined by the functor Dual G . (As angular momenta p i are in a bijectivecorrespondence with angular velocities ẋ i , every component of the functorDual G is invertible.)Applying the functor Lie to the biodynamical configuration manifoldM (Figure 3.6), we get the product–tree of the same anthropomorphicstructure, but having tangent Lie algebras so(k) i as vertices, instead of thegroups SO(k) i . Again, applying the functor Can to M, we get the product–tree of the same anthropomorphic structure, but this time having cotangentLie algebras so(k) ∗ i as vertices.The functor Lie defines the second–order Lagrangian formalism on thetangent bundle T M (i.e., the velocity phase–space manifold) while the func-

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