Zobrazeno 1 - 10
of 252
pro vyhledávání: '"Cicogna, G."'
Autor:
Cicogna, G., Pegoraro, F.
We identify and discuss a family of azimuthally symmetric, incompressible, magnetohydrodynamic plasma equilibria with poloidal and toroidal flows in terms of solutions of the Generalized Grad Shafranov (GGS) equation. These solutions are derived by e
Externí odkaz:
http://arxiv.org/abs/1502.04542
We specialize Olver's and Rosenau's side condition heuristics for the determination of particular invariant sets of ordinary differential equations. It turns out that side conditions of so-called LaSalle type are of special interest. Moreover we put
Externí odkaz:
http://arxiv.org/abs/1406.4111
Autor:
Cicogna, G., Walcher, S.
Publikováno v:
Acta Appl. Mathem. Vol. 70, 95 (2002)
We discuss the convergence problem for coordinate transformations which take a given vector field into Poincar\'e-Dulac normal form. We show that the presence of linear or nonlinear Lie point symmetries can guaranteee convergence of these normalizing
Externí odkaz:
http://arxiv.org/abs/1309.4233
Autor:
Cicogna, G., Gaeta, G.
Publikováno v:
J. Phys. A: Math. Gen. 34, 491 (2001)
When we consider a differential equation $\Delta=0$ whose set of solutions is ${{\cal S}}_\Delta$, a Lie-point exact symmetry of this is a Lie-point invertible transformation $T$ such that $T({{\cal S}}_\Delta)={{\cal S}}_\Delta$, i.e. such that any
Externí odkaz:
http://arxiv.org/abs/1309.2407
Publikováno v:
J. Phys. A: Math. Gen. 5065 (1998)
We discuss how the presence of a suitable symmetry can guarantee the perturbative linearizability of a dynamical system - or a parameter dependent family - via the Poincar\'e Normal Form approach. We discuss this at first formally, and later pay atte
Externí odkaz:
http://arxiv.org/abs/1309.2405
Autor:
Cicogna, G.
Publikováno v:
J. Phys. A: Math. Gen. L179 (1995)
It is shown that, under suitable conditions, involving in particular the existence of analytic constants of motion, the presence of Lie point symmetries can ensure the convergence of the transformation taking a vector field (or dynamical system) into
Externí odkaz:
http://arxiv.org/abs/1309.2076
Autor:
Cicogna, G., Gaeta, G.
Publikováno v:
Int. J. Geom. Meths. Mod. Phys. 6 (2009), 1305-1321
Symmetry properties are at the basis of integrability. In recent years, it appeared that so called "twisted symmetries" are as effective as standard symmetries in many respects (integrating ODEs, finding special solutions to PDEs). Here we discuss ho
Externí odkaz:
http://arxiv.org/abs/1002.1489
Autor:
Cicogna, G.
The notion of lambda-symmetries, originally introduced by C. Muriel and J.L. Romero, is extended to the case of systems of first-order ODE's (and of dynamical systems in particular). It is shown that the existence of a symmetry of this type produces
Externí odkaz:
http://arxiv.org/abs/0802.3581
Autor:
Cicogna, G., Gaeta, G.
We give a version of Noether theorem adapted to the framework of mu-symmetries; this extends to such case recent work by Muriel, Romero and Olver in the framework of lambda-symmetries, and connects mu-symmetries of a Lagrangian to a suitably modified
Externí odkaz:
http://arxiv.org/abs/0708.3144
Autor:
Cicogna, G., Laino, M.
Publikováno v:
Rev. Math. Phys. 18, No. 1, 1-18 (2006)
Symmetry properties of PDE's are considered within a systematic and unifying scheme: particular attention is devoted to the notion of conditional symmetry, leading to the distinction and a precise characterization of the notions of ``true'' and ``wea
Externí odkaz:
http://arxiv.org/abs/math-ph/0603021