In this talk we present an algebraic method for measuring/controlling the ambiguity of an ambiguous code. A relation is established between codes and monoids, in such a way that to each class of codes corresponds a variety of monoids. It is this variety what measures the ambiguity of the given class of codes. This concept includes several forms of decipherability of codes, like unique decipherability, multiset decipherability and set decipherability, as introduced by Lempel in 1986.

We will give some examples of codes satisfying these types of decipherability, and illustrate one of the main techniques, namely the construction of the Domino Graph of a code.

Material used during the talk

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