1. Provide informal descriptions and state diagrams of pushdown automata for the languages below, on the alphabet -(x, y, z): "Informal description" means 1-4 English sentences describing the automaton operation. a. {w I w-y2xk where kit. } b. (w w-xzy where i >>o) c. {w | w-x*zx3kz where k20) d. (w | wyxy'xy where jk20)