Problem II i) Theorem 2.9 in the course text states that a function f: X → Y is continuous if and...
For metric spaces and topology Problem II. a) Show that f: X →Y is continuous if and only if f-'(C) CX is closed for every closed C CY b) Then show that a function f: X + Y is continuous if and only if f(A) < f(A) for all ACX
2. Rolle's theorem states that if F : [a, b] → R is a continuous function, differentiable on Ja, bl, and F(a) = F(b) then there exists a cela, b[ such that F"(c) = 0. (a) Suppose g : [a, b] → R is a continuous function, differentiable on ja, bl, with the property that (c) +0 for all cela, b[. Using Rolle's theorem, show that g(a) + g(b). [6 Marks] (b) Now, with g still as in part (a),...
Let X and Y be topological spaces, and let X × y be equipped with the product topology. Let yo E Y be fixed. Define the map f XXx Y by f(x) (x, yo) Prove that f is continuous, Let X and Y be topological spaces, and let X × y be equipped with the product topology. Let yo E Y be fixed. Define the map f XXx Y by f(x) (x, yo) Prove that f is continuous,
Problem II. i) Let Tı and T2 be two topologies on the same space X. Suppose that T2 is finer than η. If (X,n) is compact, does it follow that (X,2) is compact? Conversely, if (X, T2) is compact, does it follow that (X, Ti) is compact? la. ii) Let Y C X be equipped with the subspace topology. Show that Y is compact in the subspace topology if and only if any cover of Y with open sets in...
a) Prove the following theorem: Let f:(x,d)-(Y,p) be bijective and continuous. Then f is a topological mapping iff: VUCX: U open = f(U) open in Y. b) Þrove the following theorem: Let f :(X,,d) (X ,d) and f:(X2,d)) (X 3,d) be topological mappings, Then f of, (the composition of the two functions) is topological.
7.7.4 The hypotheses of Theorem 7.24 require that f be differentiable on all of the interval I. You might think that a positive derivative at a single point also implies that the function is increasing, at least in a neighborhood of that point. This is not true. Consider the function /(z) _{0,/2 + ra sin.ri. if 0 (e) Prove that if a function F is differentiable on a neighborhood of ro with F(ro)0 and F is continuous at zo, then...
7. State Taylor's theorem for a function f(x, y) of two variables and prove it by using Taylor's theorem for a single variable function. 7. State Taylor's theorem for a function f(x, y) of two variables and prove it by using Taylor's theorem for a single variable function.
l maps is a quotient map. 4, Let ( X,T ) be a topological space, let Y be a nonempty set, let f be a function that maps X onto Y, let U be the quotient topology on induced by f, and let (Z, V) be a topological space. Prove that a function g:Y Z is continuous if and only if go f XZ is continuous. l maps is a quotient map. 4, Let ( X,T ) be a topological...
THEOREM. Suppose that F(x, y) = (P(x, y), Q(x, y)) is a vector-valued function of two variables and that the domain of P(x,y) and Q(x,y) is all of R2. Then it is possible to find a function f(x,y) satisfying Vf = F if and only if Py = Q. Instructions: Use this Theorem to test whether or not each of the following vector-valued functions F(x,y) has a function f(x, y) that satisfies VS = F (that is, if there is...
Suppose that f(x) is a convex function with continuous first partials defined on a convex set C in R". Prove that a point x* in C is a global minimizer of f(x) on C if and only if Vf(x*)-(x - x*)2 0 for all x in C. Suppose that f(x) is a convex function with continuous first partials defined on a convex set C in R". Prove that a point x* in C is a global minimizer of f(x) on...