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Sonnenschein–Mantel–Debreu Theorem
The Sonnenschein–Mantel–Debreu theorem is an important result in general equilibrium economics, proved by Gérard Debreu, , and Hugo F. Sonnenschein in the 1970s. It states that the excess demand curve for an exchange economy populated with utility-maximizing rational agents can take the shape of any function that is continuous, has homogeneity degree zero, and is in accordance with Walras's law. This implies that the excess demand function does not take a well-behaved form even if each agent has a well-behaved utility function. Market processes will not necessarily reach a unique and stable equilibrium point. More recently, Jordi Andreu, Pierre-André Chiappori, and Ivar Ekeland extended this result to market demand curves, both for individual commodities and for the aggregate demand of an economy as a whole. This means that demand curves may take on highly irregular shapes, even if all individual agents in the market are perfectly rational. In contrast with usual assum ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
General Equilibrium Theory
In economics, general equilibrium theory attempts to explain the behavior of supply, demand, and prices in a whole economy with several or many interacting markets, by seeking to prove that the interaction of demand and supply will result in an overall general equilibrium. General equilibrium theory contrasts to the theory of ''partial'' equilibrium, which analyzes a specific part of an economy while its other factors are held constant. In general equilibrium, constant influences are considered to be noneconomic, therefore, resulting beyond the natural scope of economic analysis. The noneconomic influences is possible to be non-constant when the economic variables change, and the prediction accuracy may depend on the independence of the economic factors. General equilibrium theory both studies economies using the model of equilibrium pricing and seeks to determine in which circumstances the assumptions of general equilibrium will hold. The theory dates to the 1870s, particularly t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frank Hahn
Frank Horace Hahn FBA (26 April 1925 – 29 January 2013) was a British economist whose work focused on general equilibrium theory, monetary theory, Keynesian economics and critique of monetarism. A famous problem of economic theory, the conditions under which money, which is intrinsically worthless, can have a positive value in a general equilibrium, is called "Hahn's problem" after him. One of Hahn's main abiding concerns was the understanding of Keynesian (Non-Walrasian) outcomes in general equilibrium situations. Biography Early life and education Frank Hahn was born on 26 April 1925 in Berlin to Arnold and Maria Hahn, their roots in German and Czech speaking Jewish communities respectively. Arnold Hahn was a chemist by profession and a writer. Arnold and Maria Hahn with their two sons, Peter and Frank, moved to Prague in 1931 (or possibly 1934) and left for England in 1938. Frank's older brother was Peter Hahn (8 November 1923 – 28 August 2007) who became an eminent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Demand Curve
In economics, a demand curve is a graph depicting the relationship between the price of a certain commodity (the ''y''-axis) and the quantity of that commodity that is demanded at that price (the ''x''-axis). Demand curves can be used either for the price-quantity relationship for an individual consumer (an individual demand curve), or for all consumers in a particular market (a market demand curve). It is generally assumed that demand curves slope down, as shown in the adjacent image. This is because of the law of demand: for most goods, the quantity demanded falls if the price rises. Certain unusual situations do not follow this law. These include Veblen goods, Giffen goods, and speculative bubbles where buyers are attracted to a commodity if its price rises. Demand curves are used to estimate behaviour in competitive markets and are often combined with supply curves to find the equilibrium price (the price at which sellers together are willing to sell the same amount as bu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Utility
As a topic of economics, utility is used to model worth or value. Its usage has evolved significantly over time. The term was introduced initially as a measure of pleasure or happiness as part of the theory of utilitarianism by moral philosophers such as Jeremy Bentham and John Stuart Mill. The term has been adapted and reapplied within neoclassical economics, which dominates modern economic theory, as a utility function that represents a single consumer's preference ordering over a choice set but is not comparable across consumers. This concept of utility is personal and based on choice rather than on pleasure received, and so is specified more rigorously than the original concept but makes it less useful (and controversial) for ethical decisions. Utility function Consider a set of alternatives among which a person can make a preference ordering. The utility obtained from these alternatives is an unknown function of the utilities obtained from each alternative, not the sum of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homothetic Preferences
In consumer theory, a consumer's preferences are called homothetic if they can be represented by a utility function which is homogeneous of degree 1. For example, in an economy with two goods x,y, homothetic preferences can be represented by a utility function u that has the following property: for every a>0: ::u(a\cdot x,a\cdot y) = a\cdot u(x,y) In mathematics, a homothetic function is a monotonic transformation of a function which is homogeneous; however, since ordinal utility functions are only defined up to an increasing monotonic transformation, there is a small distinction between the two concepts in consumer theory. In a model where competitive consumers optimize homothetic utility functions subject to a budget constraint, the ratios of goods demanded by consumers will depend only on relative prices, not on income or scale. This translates to a linear expansion path in income: the slope of indifference curves is constant along rays beginning at the origin. This is to sa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Euclidean Vector
In mathematics, physics, and engineering, a Euclidean vector or simply a vector (sometimes called a geometric vector or spatial vector) is a geometric object that has magnitude (or length) and direction. Vectors can be added to other vectors according to vector algebra. A Euclidean vector is frequently represented by a '' directed line segment'', or graphically as an arrow connecting an ''initial point'' ''A'' with a ''terminal point'' ''B'', and denoted by \overrightarrow . A vector is what is needed to "carry" the point ''A'' to the point ''B''; the Latin word ''vector'' means "carrier". It was first used by 18th century astronomers investigating planetary revolution around the Sun. The magnitude of the vector is the distance between the two points, and the direction refers to the direction of displacement from ''A'' to ''B''. Many algebraic operations on real numbers such as addition, subtraction, multiplication, and negation have close analogues for vectors, operations whic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homogenous Function
In mathematics, a homogeneous function is a function of several variables such that, if all its arguments are multiplied by a scalar, then its value is multiplied by some power of this scalar, called the degree of homogeneity, or simply the ''degree''; that is, if is an integer, a function of variables is homogeneous of degree if :f(sx_1,\ldots, sx_n)=s^k f(x_1,\ldots, x_n) for every x_1, \ldots, x_n, and s\ne 0. For example, a homogeneous polynomial of degree defines a homogeneous function of degree . The above definition extends to functions whose domain and codomain are vector spaces over a field : a function f : V \to W between two -vector spaces is ''homogeneous'' of degree k if for all nonzero s \in F and v \in V. This definition is often further generalized to functions whose domain is not , but a cone in , that is, a subset of such that \mathbf\in C implies s\mathbf\in C for every nonzero scalar . In the case of functions of several real variables and real ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microfoundations
Microfoundations are an effort to understand macroeconomic phenomena in terms of economic agents' behaviors and their interactions.Maarten Janssen (2008),Microfoundations, in ''The New Palgrave Dictionary of Economics'', 2nd ed. Research in microfoundations explores the link between Macroeconomics, macroeconomic and Microeconomics, microeconomic principles in order to explore the aggregate relationships in macroeconomic models. During recent decades, macroeconomists have attempted to combine microeconomic models of individual behaviour to derive the relationships between macroeconomic variables. Presently, many macroeconomic models, representing different theories, are Dynamic stochastic general equilibrium, derived by aggregating microeconomic models, allowing economists to test them with both macroeconomic and microeconomic data. However, microfoundations research is still heavily debated with management, strategy and organization scholars having varying views on the "micro-macro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mathematical Economics
Mathematical economics is the application of mathematical methods to represent theories and analyze problems in economics. Often, these applied methods are beyond simple geometry, and may include differential and integral calculus, difference and differential equations, matrix algebra, mathematical programming, or other computational methods. Proponents of this approach claim that it allows the formulation of theoretical relationships with rigor, generality, and simplicity. Mathematics allows economists to form meaningful, testable propositions about wide-ranging and complex subjects which could less easily be expressed informally. Further, the language of mathematics allows economists to make specific, positive claims about controversial or contentious subjects that would be impossible without mathematics. Much of economic theory is currently presented in terms of mathematical economic models, a set of stylized and simplified mathematical relationships asserted to clarify ass ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Overproduction
In economics, overproduction, oversupply, excess of supply or glut refers to excess of supply over demand of products being offered to the market. This leads to lower prices and/or unsold goods along with the possibility of unemployment. The demand side equivalent is underconsumption Underconsumption is a theory in economics that recessions and stagnation arise from an inadequate consumer demand, relative to the amount produced. In other words, there is a problem of overproduction and overinvestment during a demand crisis. The ...; some consider supply and demand two sides to the same coin – excess supply is only relative to a given demand, and insufficient demand is only relative to a given supply – and thus consider overproduction and underconsumption equivalent. Overproduction is often attributed as due to previous overinvestment – creation of excess productive capacity, which must then either lie idle (or under capacity), which is unprofit (economics), profitable, or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shortage
In economics, a shortage or excess demand is a situation in which the demand for a product or service exceeds its supply in a market. It is the opposite of an excess supply ( surplus). Definitions In a perfect market (one that matches a simple microeconomic model), an excess of demand will prompt sellers to increase prices until demand at that price matches the available supply, establishing market equilibrium. In economic terminology, a shortage occurs when for some reason (such as government intervention, or decisions by sellers not to raise prices) the price does not rise to reach equilibrium. In this circumstance, buyers want to purchase more at the market price than the quantity of the good or service that is available, and some non-price mechanism (such as "first come, first served" or a lottery) determines which buyers are served. So in a perfect market the only thing that can cause a shortage is price. In common use, the term "shortage" may refer to a situation whe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Excess Demand Function
In microeconomics, excess demand is a phenomenon where the demand for goods and services exceeds that which the firms can produce. In microeconomics, an excess demand function is a function expressing excess demand for a product—the excess of quantity demanded over quantity supplied—in terms of the product's price and possibly other determinants. It is the product's demand function minus its supply function. In a pure exchange economy, the excess demand is the sum of all agents' demands minus the sum of all agents' initial endowments. A product's excess supply function is the negative of the excess demand function—it is the product's supply function minus its demand function. In most cases the first derivative of excess demand with respect to price is negative, meaning that a higher price leads to lower excess demand. The price of the product is said to be the equilibrium price if it is such that the value of the excess demand function is zero: that is, when th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
