Examples of quotient spaces
1. Let ~ be the equivalence relation (x1, x2) ~ (y1, y2) iff x2 = y2 on R2. Then R2/~ is homeomorphic to R.
2. Let ~ be the equivalence relation x ~ y iff x and y are diametrically opposite, on S1. Then S1/~ is homeomorphic to S1. Is the corresponding result for S2 true?
Note: Sn : the n-sphere, {x ?Rn+1 | |x| =1}
S1 is the unit circle inR2.