1. a) Let (x, d) be a metric space. Define a flow on (x, d). b) Let (x, {phi_t}) be  a flow on a metric space x. what is x0 in x a fixed point of the flow? c) When do you say that a fixed point x0 in x is Poincare stable? d) When do you say that a fixed point x0 is Lyapunov stable? Use Analysis to complete the following statements.

3. Let V denote the vector space of all functions f : R" → R, equipped with addition + : V × V → V defined via (ƒ+g)(x) = f(x)+ g(x), x ≤ R", and scalar multiplication : R × V → V defined via (\ · ƒ)(x) = \ƒ(x), ● x ER". Rº Now let W = {ƒ : R^ → R : ƒ(x) = ax + b for some a, b € R}, i.e. the space of all linear functions R" → R. (a) Find a basis for W. You should prove that it is indeed a basis.

Which of the following prescriptions does not define a linear mapping A: R^2 ---> R^2?