Solution for Exercise 05 from Chapter 01 in Baby Rudin

[gapry]

This pull request provides the solution for Exercise 05, Chapter 01, from the third edition of Principles of Mathematical Analysis by Walter Rudin.

[ceciliachan1979]

Old PR note, rebased to main, this solution still have a major flaw.

[gapry]

Old PR note, rebased to main, this solution still have a major flaw.

Got it, I will fix it in 12 hrs.

[ceciliachan1979]

@E7-87-83, logic 上我搵唔到問題了，但硬係覺得 presentation 好怪，你可唔可以指點一下？

[E7-87-83]

".... we know that for all y ∈ −A, y ≤ sup(−A) is true."
呢句需要證明。

[gapry]

".... we know that for all y ∈ −A, y ≤ sup(−A) is true." 呢句需要證明。

係咪要證明 sup(-A) 係 exist ? ? ?

[E7-87-83]

哦……

不如咁改寫 "Let’s claim y = −x. By definition of sup, for all y ∈ −A, y ≤ sup(−A) is true."