Now showing items 170-189 of 254

    • Presentation
      Icon

      Obtaining combinatorial structures associated with low-dimensional Leibniz algebras 

      Ceballos González, Manuel; Núñez Valdés, Juan; Tenorio Villalón, Ángel Francisco (2013)
      In this paper, we analyze the relation between Leibniz algebras and combinatorial structures. More concretely, we study ...
    • Article
      Icon

      On abelian subalgebras and ideals of maximal dimension in supersolvable Lie algebras 

      Ceballos González, Manuel; Towers, David A. (Elsevier, 2014-02)
      In this paper, the main objective is to compare the abelian subalgebras and ideals of maximal dimension for finite-dimensional ...
    • Article
      Icon

      On certain anti-invariant submanifolds of an S-manifold 

      Cabrerizo Jaraíz, José Luis; Fernández Fernández, Luis Manuel (Sociedade Portuguesa de Matemática, 1993)
      In this paper, the geometry of certain anti-invariant submanifolds of an S-manifold, namely those which are normal to the structure vector fields, is studied.
    • Presentation
      Icon

      On generalized Sasakian-space-forms 

      Carriazo Rubio, Alfonso; Blair, David E.; Alegre Rueda, Pablo Sebastián (2004)
      We study contact metric and trans-Sasakian generalized Sasakian-space-forms. We also give some interesting examples of generalized Sasakian-space-forms by using warped products and conformal changes of metric.
    • Article
      Icon

      On manifolds with nonhomogeneous factors 

      Cárdenas Escudero, Manuel Enrique; Fernández Lasheras, Francisco Jesús; Quintero Toscano, Antonio Rafael; Repovš, Dušan (Springer, 2012-06)
      We present simple examples of finite-dimensional connected homogeneous spaces (they are actually topological manifolds) ...
    • Article
      Icon

      On pseudo-Einstein hypersurfaces of ℋ2n+s 

      Cabrerizo Jaraíz, José Luis; Fernández Fernández, Luis Manuel; Fernández Andrés, Manuel (Indian National Science Academy, 1996-05)
      In this paper, some properties of the geometry of pseudo-Einstein hypersurfaces of the S-manifold ℋ 2n+s are studied and a theorem concerning their principal curvatures is obtained.
    • Article
      Icon

      On slant submanifolds of neutral Kaehler manifolds 

      Arslan, Kadri; Carriazo Rubio, Alfonso; Chen, Bang-Yen; Murathan, Cengizhan (Mathematical Society of the Republic of China, 2010-04)
      An indefinite Riemannian manifold is called neutral it its index is equal to one half of its dimension and an indefinite ...
    • Presentation
      Icon

      On surfaces in digital topology 

      Ayala Gómez, Rafael; Domínguez Murillo, Eladio; Francés Román, Ángel Ramón; Quintero Toscano, Antonio Rafael; Rubio Sender, Julio (1995)
      In R. Ayala, E. Domínguez, A.R. Francés, A. Quintero, J. Rubio. A Polyhedral Approach to Digital Topology a new framework ...
    • Article
      Icon

      On the classifying space for proper actions of groups with cyclic torsion 

      Antolín Pichel, Yago; Flores Díaz, Ramón Jesús (De Gruyter, 2014-01)
      In this paper we introduce a common framework for describing the topological part of the Baum-Connes conjecture for a ...
    • Article
      Icon

      On the connectivity of skeletons of pseudomanifolds with boundary 

      Ayala Gómez, Rafael; Chávez de Diego, María José; Márquez Pérez, Alberto; Quintero Toscano, Antonio Rafael (Mathematical Institute, Academy of Sciences of the Czech Republic, 2002)
      In this note we show that 1-skeletons and 2-skeletons of n-pseudomanifolds with full boundary are (n+ 1)-connected graphs and n-connected 2-complexes, respectively. This generalizes previous results due to Barnette and Woon.
    • Article
      Icon

      On the existence of almost contact structure and the contact magnetic field 

      Cabrerizo Jaraíz, José Luis; Fernández Andrés, Manuel; Gómez Casanueva, Juan Salvador (Springer, 2009-10)
      In this short note we give a simple proof of the existence of an almost contact metric structure on any orientable ...
    • Article
      Icon

      On the Freudenthal extensions of proper confluent maps 

      Charatonik, Wlodzimierz J; Fernández Bayort, Tomás; Quintero Toscano, Antonio Rafael (University of Houston, 2012)
      In this paper we study when Freudenthal extensions of proper maps preserve the (weak, semi) confluency. Also the extensions to the Alexandroff one-point compactificaton are considered.
    • Article
      Icon

      On the functoriality of cohomology of categories 

      Muro Jiménez, Fernando (Elsevier, 2006-03)
      In this paper we show that the Baues-Wirsching complex used to define cohomology of categories is a 2-functor from a certain ...
    • Article
      Icon

      On the idempotency of some composite functors 

      Flores Díaz, Ramón Jesús (Springer, 2012-01)
      We present examples of localization functors whose composition with certain cellularization functors is not idempotent, and vice versa.
    • Article
      Icon

      On the locally finite chain algebra of a proper homotopy type 

      Baues, Hans Joachim; Quintero Toscano, Antonio Rafael (Belgian Mathematical Society, 1996)
      In the classical paper [A-H] Adams-Hilton constructed a free chain algebra which is an important algebraic model of a ...
    • Article
      Icon

      On the topology of locally 2-connected Peano continua 

      Chávez de Diego, María José; Fernández Bayort, Tomás; Quintero Toscano, Antonio Rafael; Villar Liñán, María Trinidad (Rocky Mountain Mathematics Consortium, 2012)
      Several recent results by Thomassen ([23 The locally connected compatc metric spaces embeddable in the plane, Combinatorica ...
    • Article
      Icon

      On totally geodesic invariant submanifolds of an S-manifold 

      Fernández Fernández, Luis Manuel (Real Academia de Ciencias de Zaragoza, 1988)
      In [1] Blair, O.E.: 1970, J. Diff. Geom. 4, (155-167), S-manifolds, which reduce in a special case to Sasakian manifolds, ...
    • Article
      Icon

      On ξ-conformally flat contact metric manifolds 

      Zhen, Guo; Cabrerizo Jaraíz, José Luis; Fernández Fernández, Luis Manuel; Fernández Andrés, Manuel (Indian National Science Academy, 1997-06)
      In this paper, the notion of ξ-conformally flat on a contact metric structure is introduced and it is proved that any ...
    • Article
      Icon

      One-relator groups and proper 3-realizability 

      Cárdenas Escudero, Manuel Enrique; Fernández Lasheras, Francisco Jesús; Quintero Toscano, Antonio Rafael; Repovš, Dušan (European Mathematical Society, 2009)
      How different is the universal cover of a given finite 2-complex from a 3-manifold (from the proper homotopy viewpoint)? ...
    • Article
      Icon

      Optimal inequalities, contact delta-invariants and their applications 

      Chen, Bang-Yen; Martín Molina, Verónica (Malaysian Mathematical Sciences Society, 2013)
      Associated with a k-tuple (n1, . . . , nk) ∈ S(2n + 1) with n ≥ 1, we define a contact δ-invariant, δc (n1, . . . , nk), ...