GATE 2023 · CS - Forenoon
Consider the pushdown automaton (PDA) P below, which runs on the input alphabet {a,b}, has stack alphabet {⊥,A}, and has three states {s,p,q}, with s being the start state. A transition from state u to state v, labelled c/X/γ, where c is an input symbol or ε, X is a stack symbol, and γ is a string of stack symbols, represents the fact that in state u, the PDA can read c from the input, with X on the top of its stack, pop X from the stack, push in the string γ on the stack, and go to state v. In the initial configuration, the stack has only the symbol ⊥ in it. The PDA accepts by empty stack.
Which one of the following options correctly describes the language accepted by P?