0
find the closure of these sets on the ordered square

$$A = \{(1/n)\times 0 | n\in \mathbb{Z}_+\}$$

i was thinking about this question and i found the answer here

Finding the closure of some subsets of the ordered square

As im unot understanding this answer as mark in red colour

enter image description here

Pliz help me and thanks in advance

jasmine
  • 14,457
  • 1
    Did you make a sketch as suggested in the text? If so, what did it look like? – Andreas Blass Mar 13 '18 at 01:30
  • @AndreasBlass..i was trying to draw,,but could not understand how can i sketch ? as i can draw suppose if a=0, b=1/3 and C= 1/2 and d = 1 as i can locate this point on XY coordinate – jasmine Mar 13 '18 at 01:39
  • 2
    Using specific values like $\frac13$ and $\frac12$ was a good idea. Now check a few specific points to see whether they're in $(u,v)$, i.e., whether they're between $\langle0,\frac13\rangle$ and $\langle\frac12,1\rangle$. I suggest checking a few points on the left edge (i.e., points with first coordinate $0$), a few points with first coordinate $\frac12$, a few points in between (maybe first coordinates $\frac17$ or $\frac13$) and a few points with first coordinate beyond $\frac12$ (maybe $\frac34$). That should give you a pretty good idea of the picture and help you fill in the proof. – Andreas Blass Mar 13 '18 at 01:57
  • The def'n of A doe not make grammatical sense. Please edit. – DanielWainfleet Mar 13 '18 at 06:40
  • im not getting@DanielWainfleet what u want to say ???? – jasmine Mar 13 '18 at 11:22

0 Answers0