The concepts of Probabilistic Pushdown Automata and Probabilistic Turing Automata are defined. Then an algorithm is proposed which allows one to approximate the Turing Automation by the Pushdown Automation. The goodness of fit of this approximation is investigated, and an error bound is derived.
Ellis, Clarence A., "The Approximation of Probabilistic Turing Automata by Probabilistic Pushdown Automata ; CU-CS-020-73" (1973). Computer Science Technical Reports. 20.