Applied general-equilibrium (AGE) models have often made compromises to circumvent difficult modeling problems. One of these is avoiding endogenous zeros, ruling out important questions. Traditional perfect competition models: when do technologies or trade links switch from active to inactive or...

The incorporation of increasing returns and imperfect competition into applied general-equilibrium (AGE) models, beginning with Harris (1984), led to much larger welfare effects from changes such as trade liberalization. But the imperfect competition side of these IO developments has often...