Statement: Some doors are walls. All walls are floors. All floors are rooms. Some rooms are windows. Conclusions: I. All walls are rooms. II. Some rooms are doors. III. Some rooms are doors. IV. Some floors are doors.

All walls are floors + All floors are rooms = A + A = A = All walls are rooms Hence I follows. Some doors are walls + All walls are floors = I + A = I = Some doors are rooms → conversion → Some rooms are doors (I). Hence II follows. Conversion of gives us III. Some doors are walls + All walls are floors = I + A = I = Some doors (I) Hence IV follows.