10-327/Homework Assignment 6

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Revision as of 00:36, 13 November 2010 by Xwbdsb (talk | contribs) (→‎Due date)
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Reading

Read sections 37-38 in Munkres' textbook (Topology, 2nd edition). Remember that reading math isn't like reading a novel! If you read a novel and miss a few details most likely you'll still understand the novel. But if you miss a few details in a math text, often you'll miss everything that follows. So reading math takes reading and rereading and rerereading and a lot of thought about what you've read. Also, preread sections 30-33, just to get a feel for the future.

Doing

Solve and submit the following problems.

Problem 1. Problem 1 on page 235 of Munkres' book.

Problem 2. Show that is homeomorphic to the cantor set .

Problem 3. Show that any function from the integers into a "cube" has a unique continuous extension to .

Problem 4. Use the fact that there is a countable dense subset within to show that the cardinality of is greater than or equal to the cardinality of .

Problem 5. Show that the cardinality of is also less than or equal to the cardinality of , and therefore it is equal to the cardinality of .

Problem 6. Show that if and if is the corresponding generalized limit, and if is a bounded sequence and is a continuous function, then .

Problem 7. Show that there is no super-limit function defined on bounded sequences of reals with values in the reals which has the following 3 properties:

  1. .
  2. .
  3. , where is "shifted once": .

Due date

This assignment is due at the end of class on Thursday, November 18, 2010.

Dror's notes above / Student's notes below

Hi Dror, how do we prove some set has smaller cardinality to another set? I mean what do you mean by that? Why in problem 5 it says that the cardinality of a set is less or equal to another set so that the cardinality are the same? Xwbdsb 00:25, 13 November 2010 (EST)

Also I am wondering what is the super-limit because it wasn't done in class and it is not covered in the book too??Xwbdsb 00:36, 13 November 2010 (EST) I remember that when proving the homeomorphism in question 2 there is another intricate argument for continuity that is not the standard definition in our topology class? Sorry Dror I am sort of lost of what to do for this assignment...Xwbdsb 00:36, 13 November 2010 (EST)