Bounds on Codes Correcting Tandem and Palindromic Duplications

In this work, we derive upper bounds on the cardinality of tandem and palindromic duplication correcting codes by deriving the generalized sphere packing bound for these error types. We first prove that an upper bound for tandem or palindromic deletions is also an upper bound for inserting the respective type of duplications. Therefore, we derive the bounds based on these special deletions as this results in tighter bounds. We determine the spheres for tandem and palindromic duplications/deletions and the number of words with a specific sphere size. Our upper bounds on the cardinality directly imply lower bounds on the redundancy which we compare with the redundancy of the best known construction correcting arbitrary burst errors. Our results indicate that the correction of palindromic duplications requires more redundancy than the correction of tandem duplications. Further, there is a significant gap between the minimum redundancy of duplication correcting codes and burst insertion correcting codes.