Consider a new type of deterministic machine, having one read-only input tape and two stacks.The tape is read-only, it cannot be written, but the head can move left, right, or do nothing. Each stack operates, independently of the other, as in a deterministic pushdown automaton:

M= (K, ?, ?1, ?2, z1, z2, ?, s)

where K is a finite set of states, ? is a finite input alphabet, ?1 and ?2 are two finite stack alphabets (?1 for the first stack, ?2 for the second stack), z1 ? ?1 and z2 ? ?2 are the initial symbols for the two stacks, s ? K is the initial state. h is a special halting state not in K, just like in a Turing machine.

(a) Give an appropriate definition for the transition function ?, for a configuration of this machine, for the yields in one step operator, and for the language accepted by this machine.