Question

In: Advanced Math

On Z we consider the family of sets τ = {Z, ∅, {−1, 0, 1}, {−2,...

On Z we consider the family of sets τ = {Z, ∅, {−1, 0, 1}, {−2, −1, 0, 1, 2}, . . . }

where the dots mean all sets like the two before that.

a) Prove that τ is a topology.

b) Is {−4, −3, −2, −1, 0, 1, 2, 3, 4} compact in this topology?

c) Is it connected?

d) Is Z compact in this topology?

e) Is it connected?

Solutions

Expert Solution


Related Solutions

Let the cyclic group {[0], [1], [2], ..., [n − 1]} be denoted by Z/nZ. Consider...
Let the cyclic group {[0], [1], [2], ..., [n − 1]} be denoted by Z/nZ. Consider the following statement: for every positive integer n and every x in Z/nZ, there exists y ∈ Z/nZ such that xy = [1]. (a) Write the negation of this statement. (b) Is the original statement true or false? Justify your answer.
Mystery(y, z: positive integer) 1 x=0 2 while z > 0 3       if z mod 2...
Mystery(y, z: positive integer) 1 x=0 2 while z > 0 3       if z mod 2 ==1 then 4                x = x + y 5       y = 2y 6       z = floor(z/2)           //floor is the rounding down operation 7 return x Simulate this algorithm for y=4 and z=7 and answer the following questions: (3 points) At the end of the first execution of the while loop, x=_____, y=______ and z=_______. (3 points) At the end of the second execution of...
Consider the matrix A = [2, -1, 1, 2; 0, 2, 1, 1; 0, 0, 2,...
Consider the matrix A = [2, -1, 1, 2; 0, 2, 1, 1; 0, 0, 2, 2; 0, 0, 0, 1]. Find P, so that P^(-1) A P is in Jordan normal form.
Consider the surfaces x^2 + y^2 + z^2 = 1 and (z +√2)2 = x^2 +...
Consider the surfaces x^2 + y^2 + z^2 = 1 and (z +√2)2 = x^2 + y^2, and let (x0, y0, z0) be a point in their intersection. Show that the surfaces are tangent at this point, that is, show that the have a common tangent plane at (x0, y0, z0).
Consider the group homomorphism φ : S3 × S5→ S5 and φ((σ, τ )) = τ...
Consider the group homomorphism φ : S3 × S5→ S5 and φ((σ, τ )) = τ . (a) Determine the kernel of φ. Prove your answer. Call K the kernel. (b) What are all the left cosets of K in S3× S5 using set builder notation. (c) What are all the right cosets of K in S3 × S5 using set builder notation. (d) What is the preimage of an element σ ∈ S5 under φ? (e) Compare your answers...
(2) Let Z/nZ be the set of n elements {0, 1, 2, . . . ,...
(2) Let Z/nZ be the set of n elements {0, 1, 2, . . . , n ? 1} with addition and multiplication modulo n. (a) Which element of Z/5Z is the additive identity? Which element is the multiplicative identity? For each nonzero element of Z/5Z, write out its multiplicative inverse. (b) Prove that Z/nZ is a field if and only if n is a prime number. [Hint: first work out why it’s not a field when n isn’t prime....
Infinite plane sheets of charge lie in z = 0, z = 2, and z =...
Infinite plane sheets of charge lie in z = 0, z = 2, and z = 4 planes with uniform surface charge densities ps1, ps2, ps3 respectively. Given that the resulting electric field intensities at the points (3, 5, 1), (1, -2, 3), and (3, 4, 5) are 0az, 6az and 4az V/m respectively, find ps1, ps2, ps3 and electric field vector at point (-2,1,-6).
Consider ​z = x ​ 1 ​ 2 ​ - 3x ​ 1 ​ x ​...
Consider ​z = x ​ 1 ​ 2 ​ - 3x ​ 1 ​ x ​ 2 ​ + 3x ​ 2 ​ 2 ​ + 4x ​ 2 ​ x ​ 3 ​ + 6x ​ 3 ​ 2 ​ . 1)Find the extreme values, if any, of the above function. 2)Check whether they are maxima or minima.
Let τ ∈ Sn be the cycle (1, 2, . . . , k) ∈ Sn...
Let τ ∈ Sn be the cycle (1, 2, . . . , k) ∈ Sn where k ≤ n. (a) For σ ∈ Sn, prove that στσ-1 = (σ(1), σ(2), . . . , σ(k)). (b) Let ρ be any cycle of length k in Sn. Prove that there exists an element σ ∈ Sn so that στσ-1 = ρ.
Find the volume of D= {(x,y,z): x^2+y^2+z^2<_ 4, x _>0, y_>0
Find the volume of D= {(x,y,z): x^2+y^2+z^2<_ 4, x _>0, y_>0
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT