4.2 Explain why was it useful to represent the location Pos of the rubbish on the floor by the term floor(Pos) and not just Pos (e.g. floor(middle) and not just middle). Hint: Omit the functor floor in the program and correspondingly simplify the clause for action pickup. Then study what happens when asking the questions: ? action( state(R, corner2, held), pickup, NewState). ?- plan(state( door, corner2, middle), state(_,, in_basket), Plan). ?- conc( Plan,,), plan(state( door, corner2, middle), state(_, in basket), Plan).