In: Advanced Math
Exercise 4.8. For each of the following, state whether it is true or false. If
true, prove. If false, provide a counterexample.
(i) LetX beasetfromRn. ThesetX isclosedifandonlyifX isconvex.
(ii) Let X and Y be sets from Rn. If X ∩Y is closed and convex then Xand Y are both closed and convex sets.
(iii) LetX beanopensetandY ⊆X. IfY ≠∅,thenY isaconvexset.
(iv) SupposeX isanopensetandY isaconvexset. IfX∩Y ⊂X then
X∪Y isopen.