66) Consider an alternate Turing machine model, in which there is an input tape on which the tape head can move in both directions but cannot write, and one or more work tapes, one of which serves as an output tape. For a function f, denoted by DSpace ( f ) , the set of languages that can be recognized by a Turning machine of this type which uses no more than f(n) squares on any work tape for any input string of length n. The only restriction we need to make on f is that f(n) > 0 for every n. The language of

67) Which of the following problems is solvable ?

68) Which of the following is not primitive recursive but partially recursive ?

69) Turing machine (TM) is more powerful than FMS (Finite State Machine) because

70) If f : N--> N. If L can be recognized by a TM T, so thatτT(n)≤ f (n) for all but finitely many n, then ( Time (f) means Time ( max ( f, 2n +2))).