  Inspired by multi-head finite automata and Watson-Crick automata in this
paper, we introduce new structure namely multi-head Watson-Crick automata where
we replace the single tape of multi-head finite automaton by a DNA double
strand. The content of the second tape is determined using a complementarity
relation similar to Watson-Crick complementarity relation. We establish the
superiority of our model over multi-head finite automata and also show that
both the deterministic and non-deterministic variant of the model can accept
non-regular unary languages. We also compare our model with parallel
communicating Watson-Crick automata systems and prove that both of them have
the same computational power.
