Now showing items 300-319 of 349

    • Stochastic smoothing of point processes for wildlife-vehicle collisions on road networks 

      Borrajo, M.I.; Comas Rodríguez, Carles; Costafreda Aumedes, Sergi; Mateu, Jorge (Springer, 2021)
      Wildlife-vehicle collisions on road networks represent a natural problem between human populations and the environment, that affects wildlife management and raise a risk to the life and safety of car drivers. We propose ...
    • Strongly formal Weierstrass non-integrability for polynomial differential systems in C2 

      Giné, Jaume; Llibre, Jaume (Bolyai Institute, University of Szeged; Hungarian Academy of Sciences, 2020)
      Recently a criterion has been given for determining the weakly formal Weierstrass non-integrability of polynomial differential systems in C2 . Here we extend this criterion for determining the strongly formal Weierstrass ...
    • Sufficient conditions for a digraph to admit a (1, ≤ l) identifying code 

      Balbuena Martínez, Camino; Dalfó, Cristina; Martínez Barona, Berenice (University of Zielona Góra, 2021)
      A identifying code in a digraph D is a subset C of vertices of D such that all distinct subsets of vertices of cardinality at most have distinct closed in-neighbourhoods within C. In this paper, we give some suffcient ...
    • Sufficient conditions for a digraph to admit a (1,≤ℓ)-identifying code 

      Balbuena Martínez, Camino; Dalfó, Cristina; Martínez Barona, Berenice (University of Zielona Góra, 2019)
      A (1, ≤ `)-identifying code in a digraph D is a subset C of vertices of D such that all distinct subsets of vertices of cardinality at most ` have distinct closed in-neighbourhoods within C. In this paper, we give some ...
    • Super edge-magic models 

      López Masip, Susana-Clara; Muntaner Batle, Francesc Antoni; Rius Font, Miquel (Springer, 2011)
      In this paper, we generalize the concept of super edge-magic graph by introducing the new concept of super edge-magic models.
    • Synthetic generation of social network data with endorsements 

      Pérez Rosés, Hebert; Sebé Feixas, Francesc (Palgrave Macmillan, 2014)
      In many simulation studies involving networks there is the need to rely on a sample network to perform the simulation experiments. In many cases, real network data is not available due to privacy concerns. In that case we ...
    • The (∆,D) and (∆,N) problems in double-step digraphs with unilateral distance 

      Dalfó, Cristina; Fiol, Miguel Angel (Indonesian Combinatorial Society (InaCombS); Graph Theory and Applications (GTA) Research Centre; University of Newcastle, Australia; Institut Teknologi Bandung (ITB), Indonesia, 2014)
      We study the (Delta,D) and (Delta,N) problems for double-step digraphs considering the unilateral distance, which is the minimum between the distance in the digraph and the distance in its converse digraph, obtained by ...
    • The 2-adic valuation of the cardinality of Jacobians of genus 2 curves over quadratic towers of finite fields 

      Garra Oronich, Ricard; Miret, Josep M. (Josep Maria); Pujolàs Boix, Jordi; Thériault, Nicolas (World Scientific Publishing, 2018)
      Given a genus 2 curve C defined over a finite field Fq of odd characteristic such that 2|#Jac(C)(Fq), we study the growth of the 2-adic valuation of the cardinality of the Jacobian over a tower of quadratic extensions of ...
    • The center problem and composition condition for Abel differential equations 

      Giné, Jaume; Grau Montaña, Maite; Santallusia Esvert, Xavier (Elsevier, 2015)
      The classical Poincaré center-focus problem for planar polynomial systems of ordinary differential equations can be transformed, in certain particular cases, to the center problem of a trigonometric Abel differential ...
    • The center problem for a 2:-3 resonant cubic Lotka–Volterra system 

      Dolićanin, Diana; Giné, Jaume; Oliveira, Regilene; Romanovski, Valery G. (Elsevier, 2013)
      In this paper we obtain conditions on the coefficients of a cubic Lotka–Volterra system of the form equation(1) x=x(2-a20x2-a11xy-a02y2), ẏ=y(-3+b20x2+b11xy+b02y2), which fulfillment yields the existence in a ...
    • The center problem for Z_2-symmetric nilpotent vector fields 

      Algaba, Antonio; García, Cristóbal; Giné, Jaume; Llibre, Jaume (Elsevier, 2018)
      We say that a polynomial differential system ˙x = P(x, y), ˙y = Q(x, y) having the origin as a singular point is Z2-symmetric if P(−x, −y) = −P(x, y) and Q(−x, −y) = −Q(x, y). It is known that there are nilpotent centers ...
    • The cubic polynomial differential systems with two circles as algebraic limit cycles 

      Giné, Jaume; Llibre, Jaume; Valls, Claudia (Walter de Gruyter GmbH, 2018)
      In this paper we characterize all cubic polynomial differential systems in the plane having two circles as invariant algebraic limit cycles.
    • The cyclicity of polynomial centers via the reduced bautin depth 

      García, I. A. (Isaac A.) (American Mathematical Society, 2016)
      We describe a method for bounding the cyclicity of the class of monodromic singularities of polyn omial planar families of vector fields X λ with an analytic Poincar e first return map having a polynomial Bautin ideal B ...
    • The Degree/Diameter Problem for Mixed Abelian Cayley Graphs 

      López Lorenzo, Ignacio; Pérez Rosés, Hebert; Pujolàs Boix, Jordi (Elsevier, 2017-11-20)
      This paper investigates the upper bounds for the number of vertices in mixed abelian Cayley graphs with given degree and diameter. Additionally, in the case when the undirected degree is equal to one, we give a construction ...
    • The degree/diameter problem in maximal planar bipartite graphs 

      Dalfó, Cristina; Huemer, Clemens; Salas Piñón, Julián (Electronic Journal of Combinatorics, 2016)
      The (∆, D) (degree/diameter) problem consists of finding the largest possiblenumber of verticesnamong all the graphs with maximum degree ∆ and diameter D. We consider the (∆, D) problem for maximal planar bipartite ...
    • The diameter of cyclic Kautz digraphs 

      Böhmová, Katerina; Dalfó, Cristina; Huemer, Clemens (Faculty of Sciences and Mathematics, University of Nis, Serbia, 2017)
      We present a new kind of digraphs, called cyclic Kautz digraphs CK(d, ɭ), which are subdigraphs of the well-known Kautz digraphs K(d,ɭ). The latter have the smallest diameter among all digraphs with their number of ...
    • The Hopf cyclicity of the centers of a class of quintic polynomial vector fields 

      García, I. A. (Isaac A.); Llibre, Jaume; Maza Sabido, Susanna (Elsevier, 2015-01-20)
      We consider families of planar polynomial vector fields having a singularity with purely imaginary eigenvalues for which a basis of its Bautin ideal B is known. We provide an algorithm for computing an upper bound of the ...
    • The inverse integrating factor and the Poincaré map 

      García, I. A. (Isaac A.); Giacomini, Héctor; Grau Montaña, Maite (American Mathematical Society, 2010)
      This work is concerned with planar real analytic differential systems with an analytic inverse integrating factor defined in a neighborhood of a regular orbit. We show that the inverse integrating factor defines an ...
    • The jumping knight and other (super) edge-magic constructions 

      López Masip, Susana-Clara; Muntaner Batle, Francesc Antoni; Rius Font, Miquel (Springer, 2014)
      Let G be a graph of order p and size q with loops allowed. A bijective function f:V(G)∪E(G)→{i}p+qi=1 is an edge-magic labeling of G if the sum f(u)+f(uv)+f(v)=k is independent of the choice of the edge uv. The constant k ...
    • The Manhattan Product of Digraphs 

      Comellas, Francesc; Dalfó, Cristina; Fiol, Miguel Angel (Indonesian Combinatorial Society (InaCombS); Graph Theory and Applications (GTA) Research Centre; University of Newcastle, Australia; Institut Teknologi Bandung (ITB), Indonesia, 2013)
      We study the main properties of a new product of bipartite digraphs which we call Manhattan product. This product allows us to understand the subjacent product in the Manhattan street networks and can be used to built other ...