Duality and minimality in Riemannian foliations.
A compact K¨ahlerian manifoldM of dimension n satisfies hp,q(M) = hq,p(M) for each p, q.However, a compact complex manifold does not satisfy the equations in general. In this paper, we consider duality of Hodge numbers of compact complex nilmanifolds.
In his 1957 paper [1] L. Dubins considered the problem of finding shortest differentiable arcs in the plane with curvature bounded by a constant and prescribed initial and terminal positions and tangents. One can generalize this problem to non-euclidean manifolds as well as to higher dimensions (cf. [15]). Considering that the boundary data - initial and terminal position and tangents - are genuinely three-dimensional, it seems natural to ask if the n-dimensional problem always reduces to the...
For a double complex , we show that if it satisfies the -lemma and the spectral sequence induced by does not degenerate at , then it degenerates at . We apply this result to prove the degeneration at of a Hodge-de Rham spectral sequence on compact bi-generalized Hermitian manifolds that satisfy a version of -lemma.
On étudie le comportement des premières valeurs propres du laplacien agissant sur les formes différentielles lors d’un effondrement adiabatique d’un flot riemannien sur une variété compacte . Le nombre de petites valeurs propres peut alors se calculer en fonction de la cohomologie basique de , et on donne des critères spectraux pour l’annulation des classes d’Álvarez et d’Euler du flot. En outre, on définit un invariant de nature diophantienne du flot qui est lié au comportement asymptotique...