ABSTRACT
Economics today divides into several distinguishable parts. Frequently, some parts draw on the tenets and findings of other sections; for example, trade and tariff theory uses demand and pricing theory. Indeed, it is impossible for theories of trade or tariffs to exist without embodying at least some notion of the demand for products and their pricing. That process also presupposes some assumptions about the nature of products, including how frequently, if ever, new products enter or leave the product space or whether or how product specifications undergo change.
