Recognizing DNA graphs is difficult

AbstractDNA graphs are the vertex induced subgraphs of De Bruijn graphs over a four letter alphabet. In this paper, we prove the NP-hardness of various recognition problems for subgraphs of De Bruijn graphs; in particular, the recognition of DNA graphs is shown to be NP-hard. As a consequence, two open questions from a recent paper by Błażewicz et al. (Discrete Appl. Math. 98, (1999) 1) are answered in the negative