Summary
The gene assembly process that transforms the micronuclear genome to the macronuclear genome in stichotrichs ciliates is a complex DNA processing which is very interesting from the computational point of view. We shall give a survey of the notions and results concerning three molecular operations, known as ld, hi, and dlad, that have been postulated to accomplish the gene assembly process. These operations are modelled on three abstraction levels: MDS descriptors, legal strings, and overlap graphs. It turns out that these three abstractions are equivalent as far as the operational modelling of gene assembly is concerned.