Quiz, week 8

  1. Consider the Bellman equation about looking for a job: V(w)=max{w1β,b+βΣi=1npiV(wi)}.V(w) = \max \{ \frac{w}{1 - β}, b + β Σ_{i=1}^n p_i V(w'_i)\}. (ww means the wage offer, bb is unemployment benefits, and pip_i is the probability of being offered wiw'_i tomorrow.) What is the domain of the corresponding Bellman operator?

  2. Suppose the corresponding Bellman operator is a contraction. Is it continuous?

  3. If the domain of a contraction is not complete, can it have two fixed points?

  4. Suppose ff is a contraction of degree ββ on (X,d)(X, d) Does this imply g(x)=f(f(x))g(x) = f(f(x)) is a contraction?

  5. Pick any point x0x_0 inside the space (X,d)(X, d). Is the function f:XXf : X \rightarrow X defined by f(x)=x0f(x) = x_0 a contraction?

  6. Suppose f:XXf : X \rightarrow X is a contraction on (X,d)(X, d). Does this imply that XX is bounded?

  7. Consider the function f(x)=xf(x) = x on the space (X,d)(X, d). Is ff a contraction?