Picture codes with finite deciphering delay

Abstract

A two-dimensional code is defined as a set X ⊆ ∑** such that any picture over ∑ is tilable in at most one way with pictures in X. The codicity problem is in general undecidable. Very recently in [4] prefix picture codes were introduced as a decidable subclass that generalizes prefix string codes. Finite deciphering delay sets are an interesting class of string codes that coincide with prefix codes in the case of delay equal to 0. An analogous notion is introduced for picture codes and it is proved that they correspond to a bigger class of decidable picture codes that includes interesting examples and special cases. © 2014 Springer International Publishing.