Long-run equilibrium in a DiPasquale-Wheaton “Four-Quadrant Model” (4QM) is found by:
The triangle connecting the current quantity of built space, the current price of property per square foot, and the current rent per square foot.
The square that equates supply and demand.
The rectangle with vertical sides and horizontal top & bottom whose four corners just touch the four binary relationship lines in each quadrant.
The diamond whose four corners are on the four axes at the current prices and quantities.