2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/132156In this paper, we introduce a geometric structure called top, which is a trivialized bundle of plane pencils over a Riemannian 3-manifold, defined as the set of kernels of a circle of 1-forms (e.g. of contact and integrable forms) with particular properties with respect to the metric. We classify the manifolds which admit tops and we describe the associated metrics.20 pagesDifferential GeometryGeometric Topology57M50, 53D10, 53C21text