Half-blind sensing 5→ 3 Watson–Crick Automata

Watson–Crick automata are two-head machines working on a Watson–Crick tape, i.e., the inputs are double-stranded DNA molecules. In 5→ 3 5 ′ → 3 ′ Watson–Crick automata, the heads start from the two extremes of the input and the process is finished when they meet. In the new model we present in this paper, one of the heads is blind, i.e., it cannot read but it can only count the symbols it advances through in a computation step. We prove that the model is able to accept a language class which is a proper superset of the class of regular languages and, at the same time, is a proper subset of the class of linear context-free languages. Hierarchy of restricted variants is also shown.