projective space
space of 1-dimensional linear subspaces (lines passing through the origin) in a vector space
complex projective space
the space of lines in a complex vector space
real projective space
type of topological space
projective Hilbert space
projective space of a Hilbert space
projective line
one-dimensional projective space
projective plane
geometric concept of a 2D space with a "point at infinity" adjoined