ON DETERMINISTIC CD-SYSTEMS OF RESTARTING AUTOMATA

Abstract

Three variants of determinism are introduced for CD-systems of restarting automata, called strict determinism, global determinism, and local determinism. In mode = 1 globally deterministic CD-systems of restarting automata are of the same expressive power as nonforgetting deterministic restarting automata of the same type, which corresponds to the situation for nondeterministic CD-systems. On the other hand, for the various types of restarting automata without auxiliary symbols, strictly deterministic CD-systems of restarting automata are strictly less expressive than the corresponding deterministic types of nonforgetting restarting automata. Further, globally deterministic CD-systems of restarting automata can be simulated by locally deterministic CD-systems of restarting automata of the same type. In fact, we conjecture that, for all types of restarting automata without auxiliary symbols, the latter are strictly more expressive than the former, but they are strictly less expressive than the corresponding nondeterministic CD-systems of restarting automata.