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                  <mods:namePart>Delshams Valdés, Amadeu</mods:namePart>
               </mods:name>
               <mods:name>
                  <mods:role>
                     <mods:roleTerm type="text">author</mods:roleTerm>
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                  <mods:namePart>Llave Canosa, Rafael de la</mods:namePart>
               </mods:name>
               <mods:originInfo>
                  <mods:dateIssued encoding="iso8601">1999</mods:dateIssued>
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               <mods:abstract>We consider perturbations of integrable area preserving non twist maps of the annulus those&#xd;
are maps in which the twist condition changes sign These maps appear in a variety of applications notably&#xd;
transport in atmospheric Rossby waves&#xd;
We show in suitable parameter families the persistence of critical circles invariant circles whose&#xd;
rotation number is the maximum of all the rotation numbers of points in the map with Diophantine rotation&#xd;
number The parameter values with critical circles of frequency lie on a one dimensional analytic curve&#xd;
Furthermore we show a partial justication of Greenes criterion	 If analytic critical curves with Dio&#xd;
phantine rotation number  exist the residue of periodic orbits that is one fourth of the trace of the&#xd;
derivative of the return map minus with rotation number converging to converges to zero exponen&#xd;
tially fast We also show that if analytic curves exist there should be periodic orbits approximating them&#xd;
and indicate how to compute them&#xd;
These results justify in particular conjectures put forward on the basis of numerical evidence in D del&#xd;
Castillo et al Phys D &#xd;
&#xd;
&#xd;
The proof of both results relies on the successive application of an&#xd;
iterative lemma which is valid also for d dimensional exact symplectic di eomorphisms The proof of this&#xd;
iterative lemma is based on the deformation method of singularity theory</mods:abstract>
               <mods:language>
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               <mods:accessCondition type="useAndReproduction">http://creativecommons.org/licenses/by-nc-nd/2.5/es/ Open Access Attribution-NonCommercial-NoDerivs 2.5 Spain</mods:accessCondition>
               <mods:subject>
                  <mods:topic>Hamiltonian dynamical systems</mods:topic>
               </mods:subject>
               <mods:subject>
                  <mods:topic>Lagrangian functions</mods:topic>
               </mods:subject>
               <mods:subject>
                  <mods:topic>Differentiable dynamical systems</mods:topic>
               </mods:subject>
               <mods:subject>
                  <mods:topic>Hamiltonian systems</mods:topic>
               </mods:subject>
               <mods:subject>
                  <mods:topic>Greene's criterion</mods:topic>
               </mods:subject>
               <mods:subject>
                  <mods:topic>KAM theory</mods:topic>
               </mods:subject>
               <mods:subject>
                  <mods:topic>Hamilton, Sistemes de</mods:topic>
               </mods:subject>
               <mods:subject>
                  <mods:topic>Lagrange, Funcions de</mods:topic>
               </mods:subject>
               <mods:subject>
                  <mods:topic>Sistemes dinàmics diferenciables</mods:topic>
               </mods:subject>
               <mods:subject>
                  <mods:topic>Classificació AMS::37 Dynamical systems and ergodic theory::37E Low-dimensional dynamical systems</mods:topic>
               </mods:subject>
               <mods:subject>
                  <mods:topic>Classificació AMS::37 Dynamical systems and ergodic theory::37J Finite-dimensional Hamiltonian, Lagrangian, contact, and nonholonomic systems</mods:topic>
               </mods:subject>
               <mods:subject>
                  <mods:topic>Classificació AMS::70 Mechanics of particles and systems::70H Hamiltonian and Lagrangian mechanics</mods:topic>
               </mods:subject>
               <mods:titleInfo>
                  <mods:title>KAM theory and a partial justification of Greene's criterion for non-twist maps</mods:title>
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               <mods:genre>Article</mods:genre>
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