A bifurcation result for Sturm-Liouville problems with a set-valued term.
A branching method for studying stability of a solution to a delay differential equation.
A characterization of isochronous centres in terms of symmetries.
We present a description of isochronous centres of planar vector fields X by means of their groups of symmetries. More precisely, given a normalizer U of X (i.e., [X,U]= µ X, where µ is a scalar function), we provide a necessary and sufficient isochronicity condition based on µ. This criterion extends the result of Sabatini and Villarini that establishes the equivalence between isochronicity and the existence of commutators ([X,U]= 0). We put also special emphasis on the mechanical aspects of isochronicity;...
A class of growth and bounds to solutions of a differential equation.
A class of Hamiltonian systems with increasing periods.
A class of integrable polynomial vector fields
We study the integrability of two-dimensional autonomous systems in the plane of the form , , where Xs(x,y) and Ys(x,y) are homogeneous polynomials of degree s with s≥2. First, we give a method for finding polynomial particular solutions and next we characterize a class of integrable systems which have a null divergence factor given by a quadratic polynomial in the variable with coefficients being functions of tan−1(y/x).
A class of nonlinear differential equations on the space of symmetric matrices.
A class of singularly perturbed evolution systems.
A Classification Of Solutions Of Second Order Linear Differential Equations By Means Of Regularly Varying Functions
A Comparison Method for Forced Oscillations.
A comparison theorem for linear delay differential equations
In this paper property (A) of the linear delay differential equation is to deduce from the oscillation of a set of the first order delay differential equations.
A comparison theorem in the theory of the second-order linear differential transformations
A conterexample in the theory of linear singularly perturbed systems
A contribution to the phase theory of a linear second-order differential equation in the Jacobian form
A contribution to the problem of coexistence of two periodical solutions of the Hill's equation
A counterexample to the periodic orbit conjecture
A criterion for determining the 2 order linear differential equations possessing the central dispersion with the index equal to
A direct proof of a theorem by Kolmogorov in hamiltonian systems
A dynamical model of terrorism.
A Floquet-Liapunov theorem in Fréchet spaces