A regular economy is an economy characterized by an excess demand function which has the property that its slope at any equilibrium price vector is non-zero. In other words, if we graph the excess demand function against prices, then the excess demand function "cuts" the x-axis assuring that each equilibrium is locally unique. Local uniqueness in turn permits the use of comparative statics - an analysis of how the economy responds to external shocks - as long as these shocks are not too large.
An important result due to Debreu (1970) states that almost any economy, defined by an initial distribution of consumer's endowments, is regular. In technical terms, the set of nonregular economies is of Lebesgue measure zero.
Combined with the index theorem this result implies that almost any economy will have a finite (and odd) number of equilibria.
Famous quotes containing the words regular and/or economy:
“They were regular in being gay, they learned little things that are things in being gay, they learned many little things that are things in being gay, they were gay every day, they were regular, they were gay, they were gay the same length of time every day, they were gay, they were quite regularly gay.”
—Gertrude Stein (1874–1946)
“The aim of the laborer should be, not to get his living, to get “a good job,” but to perform well a certain work; and, even in a pecuniary sense, it would be economy for a town to pay its laborers so well that they would not feel that they were working for low ends, as for a livelihood merely, but for scientific, or even moral ends. Do not hire a man who does your work for money, but him who does it for love of it.”
—Henry David Thoreau (1817–1862)