The comparative advantage of many cities is based on their efficiency in the production of 'functions', e.g., business services such as finance, law, engineering, or similar functions that are used by firms in a wide range of sectors. Firms that use these functions may choose to source them...

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...