Problem 16.8 Let X and Y be compact metric spaces and let f: X →
Y...
Problem 16.8 Let X and Y be compact metric spaces and let f: X →
Y be a continuous onto map with the property that
f-1[{y}] is connected for every y∈Y. Show that ifY is
connected then so isX.
Let (X,dX),(Y,dY ) be metric spaces and f: X → Y be a continuous
bijection. Prove that if (X, dX ) is compact, then f is a
homeomorphism. (Hint: it might be convenient to use that a function
is continuous if and only if the inverse image of every open set is
open, if and only if the inverse image of every closed set is
closed).
Let X be a compact space and let Y be a Hausdorff space. Let f ∶
X → Y be continuous. Show that the image of any closed set in X
under f must also be closed in Y .
Suppose (X, dX) and (Y, dY ) are metric spaces. Define d : (X ×Y
)×(X × Y ) → R by d((x, y),(a, b)) = dX(x, a) + dY (y, b). Prove d
is a metric on X × Y .
(Connected Spaces)
(a) Let <X, d> be a metric space and E ⊆ X. Show that E is
connected iff for all p, q ∈ E, there is a connected A ⊆ E with p,
q ∈ E.
b) Prove that every line segment between two points in R^k
is connected, that is Ep,q = {tp + (1 − t)q |
t ∈ [0, 1]} for any p not equal to q in R^k.
C). Prove that every convex subset...
Let (X,d) be a metric space. The graph of f : X → R is the set
{(x, y) E X X Rly = f(x)}. If X is connected and f is continuous,
prove that the graph of f is also connected.
18.2.14. Problem. Give examples of metric spaces M and N , a
homeomorphism f : M → N , and
a Cauchy sequence (xn) in M such that the sequence ?f(xn)? is
not Cauchy in N.
18.2.15. Problem. Show that if D is a dense subset of a metric
space M and every Cauchy
sequence in D converges to a point of M, then M is
complete.
1. Let X and Y be non-linear spaces and T : X -->Y. Prove
that if T is One-to-one then T-1 exist
on R(T) and T-1 : R(T) à X is also a linear map.
2. Let X, Y and Z be linear spaces over the scalar field F, and
let T1 ϵ B (X, Y) and T2 ϵ B (Y, Z). let
T1T2(x) = T2(T1x)
∀ x ϵ X.
(i) Prove that T1T2 ϵ B
(X,Y) is also a...
Let (X, dX) and (Y, dY) be metric
spaces.Define the function
d : (X × Y ) × (X × Y ) → R
by
d ((x1, y1),
(x2,y2)) =
dx(x1,x2)+dy(y1,y2)
Prove that d is a metric on X × Y .
The curried version of let f (x,y,z) = (x,(y,z)) is
let f (x,(y,z)) = (x,(y,z))
Just f (because f is already curried)
let f x y z = (x,(y,z))
let f x y z = x (y z)
4. (Oblique Trajectory Problem) Let F(x, y) = x 2 + xy + y 2 .
Find a formula for G(x, y) such that every curve in the
one-parameter family defined by F(x, y) = c intersects every curve
in the one-parameter family defined by G(x, y) = c at a sixty
degree angle