文档介绍：Chapter Two
Budget Constraint
预算约束
Structure
Describe budget constraint
Algebra
Graph
Describe changes in budget constraint
Government programs and budget constraints
Non-linear budget lines
Consumption Sets
A consumption set (消费集)is the collection of all physically possible consumption bundles (消费束)to the consumer.
Consumption Bundle
A consumption bundle containing x1 units modity 1, x2 units modity 2 and so on up to xn units modity n is denoted by the vector (x1, x2, …, xn).
Physical Constraints
Non-negative:
Consumption set:
X={ (x1, …, xn) | x1 ³ 0, …, xn ³ 0 }
You only have 24 hours a day
Subsistence need
Etc.
Budget Constraint
What constrains consumption choice?
Budgetary
time
other resource limitations.
Budget Constraints
Commodity prices are p1, p2, …, pn.
Q: When is a bundle (x1, …, xn) affordable at prices p1, …, pn?
A: When p1x1 + …+ pnxn £ m where m is the consumer’s (disposable) e.
Budget Constraints
The bundles that are only just affordable form the consumer’s budget constraint. This is the set { (x1,…,xn) | x1 ³ 0, …, xn ³ 0 and p1x1 + …+ pnxn = m }.
Budget Constraints
The consumer’s budget set (预算集)is the set of all affordable bundles; B(p1, …, pn, m) = { (x1, …, xn) | x1 ³ 0, …, xn ³ 0 and p1x1 + …+ pnxn £ m }
The budget constraint is the upper boundary of the budget set.
Budget Set and Constraint for modities
x2
x1
Budget constraint is
p1x1 + p2x2 = m.
m /p1
m /p2