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Q30

MCQ2 marks, −0.67

Consider the pushdown automaton (PDA)  P\text{(PDA)}\;P below, which runs on the input alphabet {a,b}\{a, b\}, has stack alphabet {⊥,A}\{\perp, A\}, and has three states {s,p,q}\{s, p, q\}, with ss being the start state. A transition from state uu to state vv, labelled c/X/γc / X / \gamma, where cc is an input symbol or ϵ,X\epsilon, X is a stack symbol, and γ\gamma is a string of stack symbols, represents the fact that in state uu, the (PDA)\text{(PDA)} can read cc from the input, with XX on the top of its stack, pop XX from the stack, push in the string γ\gamma on the stack, and go to state vv. In the initial configuration, the stack has only the symbol ⊥\perp in it. The (PDA)\text{(PDA)} accepts by empty stack.

Figure 1

Which one of the following options correctly describes the language accepted by P?P ?

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