On Space-bounded Synchronized Alternating Turing Machines

We continue the study of the computational power of synchronized alternating Turing machines (SATM), introduced in [Hro86, Slo87, Slo88a, Slo88b] to allow communication via synchronization among processes of alternating Turing machines. We compare the classes of languages accepted by the four main classes of space-bounded synchronized alternating Turing machines obtained by adding or removing off-line capability and nondeterminism (1SUTM(S(n)), SUTM(S(n)), 1SATM(S(n)), and SATM(S(n))). We show various strict inclusions, equalities, and incomparabilities between these classes and those accepted by plain and modified alternating Turing machines.