11. The value of the AD-AS model, and the reason we introduce it rather than continue to rely solely on the JS-LM-FE model, stems from its ability to easily show the effects of relaxing a key assumption we employed in Chapters 9 and. 10; namely, the assumption that what households and firms expect to see and experience in the future is not affected by what they see and experience today. General equilibrium in the AD-AS model defines equilibrium values of all macroeconomic variables conditioned on what households and firms expect their values to be in the future.