On Stateless Multicounter Machines
CiE '09 Proceedings of the 5th Conference on Computability in Europe: Mathematical Theory and Computational Practice
On stateless multihead automata: Hierarchies and the emptiness problem
Theoretical Computer Science
5′ → 3′ Watson-Crick Automata With Several Runs
Fundamenta Informaticae - Non-Classical Models of Automata and Applications
DCFS'12 Proceedings of the 14th international conference on Descriptional Complexity of Formal Systems
A Survey of Results on Stateless Multicounter Automata
Fundamenta Informaticae - Words, Graphs, Automata, and Languages; Special Issue Honoring the 60th Birthday of Professor Tero Harju
Automata with modulo counters and nondeterministic counter bounds
CIAA'12 Proceedings of the 17th international conference on Implementation and Application of Automata
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A stateless k-head two-way deterministic finite automaton (k-head 2DFA), has only one state, hence the designation stateless. Its transitions depends solely on the symbols currently scanned by its k heads, and in every such transition each head can move one cell left, right, or remain stationary. An input, which is delimited by end markers, is accepted if the machine, when started with all heads on the left end marker, reaches the configuration where all the heads are on the right end marker. The nondeterministic version is denoted by k-head 2NFA.We prove that stateless (k + 1)-head 2DFAs (resp., 2NFAs) are computationally more powerful than k-head 2DFAs (resp., 2NFAs), improving a recent result where it was shown that (k + 4) heads are better than k heads.We also study stateless multihead pushdown automata in their two-way and one-way, deterministic and nondeterministic variations and show that for all these varieties, k + 1 heads allow more computational power than k heads. Finally, we give some characterizations of stateless multihead finite and multihead pushdown automata.