Symbolic encoding in symplectic maps

A general procedure to construct a generating partition in 2D symplectic maps is introduced. The implementation of the method, specifically discussed with reference to the standard map, can be easily extended to any model where chaos originates from a horseshoe-type mechanism. Symmetries arising from the symplectic structure of the dynamics are exploited to eliminate the remaining ambiguities of the encoding procedure, so that the resulting symbolic dynamics possesses the same symmetry as that of the original model. Moreover, the dividing line of the partition turns out to pass through the stability islands, in such a way as to yield a proper representation of the quasiperiodic dynamics as well as of the chaotic component. As a final confirmation of the correctness of our approach, we construct the associated pruning front and show that it is monotonous.