Let f be the mapping of S2 into R4 such that
f(x1,x2,x3)=(x12−x22,x1x2,x1x3,x2x3). This function has the same value at diametrically opposite points of
S2. Show that on passing to the quotient it defines a homeomorphism of
P2 onto a subspace of
R4.
Show likewise that the mapping g of S3 into R6 defined by
g(x1,x2,x3,x4)=(x12−x22,x1x2,x1x3+x2x4,x32−x42,x3x4,x1x4−x2x3) defines, on passing to the quotient, a homeomorphism of
P3 into
R6.