RT Journal Article T1 Ruled Surfaces in 3-Dimensional Riemannian Manifolds A1 Castrillón López, Marco A1 Rosado, M. Eugenia A1 Soria, M. Eugenia AB In this work, ruled surfaces in 3-dimensional Riemannian manifolds are studied. We determine the expressions for the extrinsic and sectional curvatures of a parametrized ruled surface, where the former one is shown to be non-positive. We also quantify the set of ruling vector fields along a given base curve which allows us to define a relevant reference frame that we refer to as. The fundamental theorem of existence and equivalence of Sannia ruled surfaces in terms of a system of invariants is given. The second part of the article tackles the concept of the striction curve, which is proven to be the set of points where the so-called Jacobi evolution function vanishes on a ruled surface. This characterisation of striction curves provides independent proof for their existence and uniqueness in space forms and disproves their existence or uniqueness in some other cases PB SpringerLink SN 1660-5446 SN 1660-5454 YR 2024 FD 2024-04-13 LK https://hdl.handle.net/20.500.14352/104717 UL https://hdl.handle.net/20.500.14352/104717 LA eng NO López, M.C., Rosado, M.E. & Soria, A. Ruled Surfaces in 3-Dimensional Riemannian Manifolds. Mediterr. J. Math. 21, 97 (2024). https://doi.org/10.1007/s00009-024-02631-2 DS Docta Complutense RD 9 abr 2025