String-matching cannot be done by a two-head one-way deterministic finite automation
Information Processing Letters
Reversal-Bounded Multicounter Machines and Their Decision Problems
Journal of the ACM (JACM)
Introduction To Automata Theory, Languages, And Computation
Introduction To Automata Theory, Languages, And Computation
On spiking neural P systems and partially blind counter machines
Natural Computing: an international journal
Hierarchies and Characterizations of Stateless Multicounter Machines
COCOON '09 Proceedings of the 15th Annual International Conference on Computing and Combinatorics
On Stateless Multicounter Machines
CiE '09 Proceedings of the 5th Conference on Computability in Europe: Mathematical Theory and Computational Practice
IBM Journal of Research and Development
Reversal-bounded multipushdown machines
Journal of Computer and System Sciences
One-reversal counter machines and multihead automata: revisited
SOFSEM'11 Proceedings of the 37th international conference on Current trends in theory and practice of computer science
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We investigate the power of (1-reversal) counter machines (finite automata with multiple counters, where each counter can ''reverse'' only once, i.e., once a counter decrements, it can no longer increment) and one-way multihead finite automata (finite automata with multiple one-way input heads) as a language acceptor. They can be non-deterministic as well as augmented with a pushdown stack. First, we prove that adding a pushdown stack properly strengthens the deterministic counter machines. Non-deterministic counter machines with a pushdown stack are then compared with multihead finite automata. The proof of their incomparability involves an interesting technique: an assumption that a language be accepted by a non-deterministic counter machine would bring a contradictory algorithm to decide an undecidable language. Furthermore, we will show that over bounded languages, these two kinds of machines have the same power, and neither non-determinism nor a pushdown stack makes them stronger.