Browsing Articles publicats (Matemàtica) by Title
Now showing items 1-20 of 258
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A blow-up method to prove formal integrability for some planar differential systems
(Shanghai Normal University & Wilmington Scientific Publisher, 2018)In this work we provide an effective method to prove the formal integrability of the resonant saddles. The method is based on the use of a blow-up and the resolution of a recurrence differential equation using induction. ... -
A Chebyshev criterion for Abelian integrals
(American Mathematical Society, 2010)We present a criterion that provides an easy sufficient condition in order that a collection of Abelian integrals has the Chebyshev property. This condition involves the functions in the integrand of the Abelian integrals ... -
A counterexample to the composition condition conjecture for polynomial Abel differential equations
(Cambridge University Press, 2019)Polynomial Abel differential equations are considered a model problem for the classical Poincaré center–focus problem for planar polynomial systems of ordinary differential equations. In the last few decades, several works ... -
A method for characterizing nilpotent centers
(Elsevier, 2014)To characterize when a nilpotent singular point of an analytic differential system is a center is of particular interest, first for the problem of distinguishing between a focus and a center, and after for studying the ... -
A Moore-like bound for mixed abelian Cayley graphs
(Elsevier B.V., 2016-09-26)We give an upper bound for the number of vertices in mixed abelian Cayley graphs with given degree and diameter. -
A new approach to gross error detection for GPS networks
(Elsevier, 2019)We present a new matrix-based approach to detect and correct gross errors in GPS geodetic control networks. The study is carried out by introducing a new matrix, whose entries are powers of a (real or complex) variable, ... -
A new general family of mixed graphs
(Elsevier, 2018)A new general family of mixed graphs is presented, which generalizes both the pancake graphs and the cycle prefix digraphs. The obtained graphs are vertex transitive and, for some values of the parameters, they constitute ... -
A new labeling construction from the ⊗h-product
(Elsevier, 2017)The -product that is referred in the title was introduced in 2008 as a generalization of the Kronecker product of digraphs. Many relations among labelings have been obtained since then, always using as a second factor a ... -
A note on a new general family of deterministic hierarchical networks
(World Scientific Publishing, 2019)It is known that many networks modeling real-life complex systems are small-word (large local clustering and small diameter) and scale-free (power law of the degree distribution), and very often they are also hierarchical. ... -
A note on Liouvillian first integrals and invariant algebraic curves
(Elsevier, 2013-02)In this work we study the existence and non-existence of finite invariant algebraic curves for a complex planar polynomial differential system having a Liouvillian first integral. -
A Privacy-Preserving Pay-by-Phone Parking System
(Institute of Electrical and Electronics Engineers (IEEE), 2017)Most cities around the world require drivers to pay for the time they occupy a parking spot. In this way, drivers are encouraged to shorten parking time so that other drivers are given a reasonable chance of finding ... -
A privacy-preserving reputation system with user rewards
(Elsevier, 2017)Reputation systems are useful to assess the trustworthiness of potential transaction partners, but also a potential threat to privacy since rating profiles reveal users’ preferences. Anonymous reputation systems resolve this ... -
A problem on edge-magic labelings of cycles
(Cambridge University Press, 2014-06-14)Kotzig and Rosa defined in 1970 the concept of edge-magic labelings as follows: let G be a simple (p, q)-graph (that is, a graph of order p and size q without loops or multiple edges). A bijective function f : V (G)∪E(G) ... -
A second order analysis of the periodic solutions for nonlinear periodic differential systems with a small parameter
(Elsevier, 2012)We deal with nonlinear T–periodic differential systems depending on a small parameter. The unperturbed system has an invariant manifold of periodic solutions. We provide the expressions of the bifurcation functions up to ... -
A sufficient condition in order that the real Jacobian conjecture in R^2 holds
(Elsevier, 2016)Let F=(f,g):R2→R2 be a polynomial map such that detDF(x,y) is different from zero for all (x,y)∈R2 and F(0,0)=(0,0). We prove that for the injectivity of F it is sufficient to assume that the higher homogeneous terms of ... -
A survey of isochronous centers
(Edicions de la Universitat de Lleida, 1999) -
A survey on the inverse integrating factor
(Springer, 2010)The relation between limit cycles of planar differential systems and the inverse integrating factor was first shown in an article of Giacomini, Llibre and Viano appeared in 1996. From that moment on, many research articles ... -
A survey on the missing Moore graph
(Elsevier, 2019-01-16)This is a survey on some known properties of the possible Moore graph (or graphs) ϒ with degree 57 and diameter 2. Moreover, we give some new results about it, such as the following. When we consider the distance partition ... -
A two-stage stochastic programming model for scheduling replacements in sow farms
(Springer Verlag, 2009)This paper presents a formulation and resolution of a two-stage stochastic linear programming model with recourse for sow farms producing piglets. The proposed model considers a medium-term planning horizon and specifically ... -
A variant of the McKay-Miller-Siran construction for Mixed Graphs
(Elsevier B.V., 2016-09-27)The Degree/Diameter Problem is an extremal problem in graph theory with applications in network design. One of the main research areas in the Degree/Diameter Problem consists of finding large graphs whose order approach ...