Kruskal’s Theory of Nearly Periodic Systems

The following sections are included:

• Introduction: Kruskal’s Approach

• The New Approach Expressed in Coordinates

• The Geometric Version of the New Approach

• Extensions and Limitations of Kruskal’s Theory

  • Secular Perturbation Theory

  • 1/ε Time of Validity for Kruskal’s Technique

  • Averaging with Multiple Frequencies

  • Averaging Over Ergodic Orbits

  • Non-uniqueness of Symmetry for Finite Perturbation