Multi-letter Reversible and Quantum Finite Automata

  title={Multi-letter Reversible and Quantum Finite Automata},
  author={Aleksandrs Belovs and Ansis Rosmanis and Juris Smotrovs},
  booktitle={Developments in Language Theory},
The regular language (a+ b)∗a (the words in alphabet {a, b} having a as the last letter) is at the moment a classical example of a language not recognizable by a one-way quantum finite automaton (QFA). Up to now, there have been introduced many different models of QFAs, with increasing capabilities, but none of them can cope with this language. We introduce a new, quite simple modification of the QFA model (actually even a deterministic reversible FA model) which is able to recognize this… CONTINUE READING