In this paper, we generalize all the results obtained on para-Kähler Lie algebras in [3] to para-Kähler Lie algebroids. In particular, we study exact para-Kähler Lie algebroids as a generalization of exact para-Kähler Lie algebras. This study leads to a natural generalization of pseudo-Hessian manifolds, we call them contravariant pseudo-Hessian manifolds. Contravariant pseudo-Hessian manifolds have many similarities with Poisson manifolds. We explore these similarities which, among others, leads to a powerful machinery to build examples of non trivial pseudo-Hessian structures. Namely, we will show that given a finite dimensional commutative and associative algebra (, .), the orbits of the action Φ of (, +) on * given by Φ( , ) = exp. We illustrate this result by considering many examples of associative commutative algebras and show that the resulting pseudo-Hessian manifolds are very interesting. K E Y W O R D S associative commutative algebras, left symmetric algebroids, para-Kähler Lie algebroids, pseudo-Hessian manifolds, symplectic Lie algebroids M S C ( 2 0 1 0 ) 13P25, 53A15, 53C15, 53D17
INTRODUCTIONRecall that a Lie algebroid is a vector bundle ←→ together with an anchor map ∶ ←→ and a Lie bracket [ , ] on Γ( ) such that, for any , ∈ Γ( ), ∈ ∞ ( ),[ , ] = [ , ] + ( )( ) .Lie algebroids are now a central notion in differential geometry and constitute an active domain of research. They have many applications in various part of mathematics and physics (see for instance [6][7][8]18]). It is a well-established fact that many classical geometrical structures involving the tangent bundle of a manifold (which has a natural structure of Lie algebroid) can be generalized to the context of Lie algebroids. Thus the notions of connections on Lie algebroids, symplectic Lie algebroids, pseudo-Riemannian Lie algebroids and so on are now usual notions in differential geometry with many applications in physics (see for instance [4,10]). On the other hand, it is important to point out that Lie algebroids generalize also Lie algebras and, for instance, if one obtains a result on the curvature of pseudo-Riemannian Lie algebroids this result holds for the curvature of pseudo-Euclidean Lie algebras and hence for the curvature of left invariant pseudo-Riemannian metrics on Lie groups.
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