2. Let (X, dx), (Y, dy), (2, dz) be metric spaces, and f : XY,g:Y + Z continu- ous maps. (a) Prove that the composition go f is continuous. (b) Prove that if W X is connected, then f(W) CY is connected.
3. (a) Let (X, dx), (Y, dy) be two metric spaces, C C X connected, and f : X+Y continuous. Show that f(C) CY is connected.
Let (X, dx), (Y, dy) be metric spaces and fn be a sequence of functions fn: XY Prove that if {fn} converges uniformly on X then for any a є x lim lim fn()- lim lim /) xa n-00 Let (X, dx), (Y, dy) be metric spaces and fn be a sequence of functions fn: XY Prove that if {fn} converges uniformly on X then for any a є x lim lim fn()- lim lim /) xa n-00
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,
A subset D of a metric space (X, d) is dense if every member of X is a limit of a sequence of elements from D. Suppose (X,d) and (Y,ρ) are metric spaces and D is a dense subset of X. 1. Prove that if f : D -» Y is uniformly continuous then there exists an extension15 of f to a if dn (E D) e X define 7(x) lim f(d,) uniformly continuous function f:X * Y. Hint: 2....
9. Let X and Y be metric spaces, and let D be a dense subset of X. (For the definition of "dense, see Problem 4 at the end of Section 3.5.) (a) Let f : X → Y and g : X → Y be continuous functions. Suppose that f(d)gld) for all d E D. Prove that f and g are the same function.
For metric spaces (X, dx) and (Y, dy) consider their Cartesian product Z-X (p18). Show that the following constructions both give metris on the product (a) Define di : Z × c, d))-dr(a, c) + dy(b, d) for (a, b), (c, d) e X x Y (b) Define (lo : Z × Z → R by writing do ((a, b), (c, d))-maux {dx (a, c), dy(b, d)) for (a, b), (c, d) E X × Y Answer the following: (c)...
(b) 4 Let F: X Y be a linear map between two normed spaces. Prove that F is continuous at Ojf and only if F is uniformly continuous on X.
1. Let (X, d) be a metric space, and U, V, W CX subsets of X. (a) (i) Define what it means for U to be open. (ii) Define what it means for V to be closed. (iii) Define what it means for W to be compact. (b) Prove that in a metric space a compact subset is closed.
Let X,Y be topological spaces, and f:X->Y a homeomorphism, I.e. f is one-to-one, onto, and f and f-1 are continuous. a.) Prove that if X is T4, so is Y. b.) Prove that if X is separable, then so is Y.