Give a complete problem formulation for each of the following problems. Choose a formulation that is precise enough to be implemented.

$1.$ There are six glass boxes in a row, each with a lock. Each of the first five boxes holds a key unlocking the next box in line; the last box holds a banana. You have the key to the first box, and you want the banana.

$2.$ You start with the sequence ABABAECCEC, or in general any sequence made from A$,$ B$,$ C$,$ and E$.$ You can transform this sequence using the following equalities: AC $=$ E$,$ AB $=$ BC$,$ BB $=$ E$,$ and Ex $=$ x for any x$.$ For example, ABBC can be transformed into AEC, and then AC$,$ and then E$.$ Your goal is to produce the sequence E$.$

$3.$ There is an n$\backslash$times n grid of squares, each square initially being either unpainted floor or a bottomless pit. You start standing on an unpainted floor square, and can either paint the square under you or move onto an adjacent unpainted floor square. You want the whole floor painted.

$4.$ A container ship is in port, loaded high with containers. There $13$ rows of containers, each $13$ containers wide and $5$ containers tall. You control a crane that can move to any location above the ship, pick up the container under it$,$ and move it onto the dock. You want the ship unloaded.