At pushdown automata is deterministic if there is at most one transition applicable to each configuration.
In automata theory, a deterministic pushdown automaton (DPDA or DPA) is a variation of the push down automata. The class of deterministic pushdown automata accepts the deterministic context free languages, a proper subset of context free languages.
A deterministic pushdown automaton has at most one legal transition for the same combination of input symbol, state, and top stack symbol.
A pushdown automaton (PDA) is a finite state machine which has an additional stack storage. The transitions a machine makes are based not only on the input and current state, but also on the stack.