Show that any open subset of R (w. standard topology) is a countable union of open...

Show that any open subset of R (w. standard topology) is a countable union of open intervals. Please explain how to do, I only understand why it is true.
What is required to fully prove this. What definitions should I be using.

Expert Solution

Colby Messinger answered 2 years ago

Show that any open subset of R (w std. topology) is a countable union of open intervals.

Show that any open subset of R (w std. topology) is a countable union of open intervals.What is the objective of this problem and enough to show ?

(Topology) Prove that the interior of a subset A of Xτ is the union of all...

(Topology) Prove that the interior of a subset A of Xτ is the union of all τ -open sets contained in A.

Show that a subset of R is open if an only if it can be expressed...

Show that a subset of R is open if an only if it can be expressed as a union of open intervals

1)Show that a subset of a countable set is also countable. 2) Let P(n) be the...

1)Show that a subset of a countable set is also countable. 2) Let P(n) be the statement that 13 + 23 +· · ·+n3 =(n(n + 1)/2)2 for the positive integer n. a) What is the statement P(1)? b) Show that P(1) is true, completing the basis step of the proof. c) What is the inductive hypothesis? d) What do you need to prove in the inductive step? e) Complete the inductive step, identifying where you use the inductive hypothesis....

In RU (R is the reals, U is the usual topology), prove that any open interval...

In RU (R is the reals, U is the usual topology), prove that any open interval (a, b) is homeomorphic to the interval (0, 1). (Hint: construct a function f : (a, b) → (0, 1) for which f(a) = 0 and f(b) = 1. Show that your map is a homeomorphism by showing that it is a continuous bijection with a continuous inverse.)

The goal is to show that a nonempty subset C⊆R is closed iff there is a...

The goal is to show that a nonempty subset C⊆R is closed iff there is a continuous function g:R→R such that C=g−1(0). 1) Show the IF part. (Hint: explain why the inverse image of a closed set is closed.) 2) Show the ONLY IF part. (Hint: you may cite parts of Exercise 4.3.12 if needed.)

1) Show that if A is an open set in R and k ∈ R \...

1) Show that if A is an open set in R and k ∈ R \ {0}, then the set kA = {ka | a ∈ A} is open.

Show that W = {f : R → R : f(1) = 0} together with usual...

Show that W = {f : R → R : f(1) = 0} together with usual addition and scalar multiplication forms a vector space. Let g : R → R and define T : W → W by T(f) = gf. Show that T is a linear transformation.

we have defined open sets in R: for any a ∈ R, there is sigma >...

we have defined open sets in R: for any a ∈ R, there is sigma > 0 such that (a − sigma, a + sigma) ⊆ A. (i) Let A and B be two open sets in R. Show that A ∩ B is open. (ii) Let {Aα}α∈I be a family of open sets in R. Show that ∪(α∈I)Aα is open. Hint: Follow the definition of open sets. Please be specific and rigorous! Thanks!

(10pt) Let V and W be a vector space over R. Show that V × W...

(10pt) Let V and W be a vector space over R. Show that V × W together with (v0,w0)+(v1,w1)=(v0 +v1,w0 +w1) for v0,v1 ∈V, w0,w1 ∈W and λ·(v,w)=(λ·v,λ·w) for λ∈R, v∈V, w∈W is a vector space over R. (5pt)LetV beavectorspaceoverR,λ,μ∈R,andu,v∈V. Provethat (λ+μ)(u+v) = ((λu+λv)+μu)+μv. (In your proof, carefully refer which axioms of a vector space you use for every equality. Use brackets and refer to Axiom 2 if and when you change them.)

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