 Projective bundle

The projective bundle of a real or complex vector bundle $E\to X$ has fiber the space of one-dimensional subspaces of $E_x$. It carries a tautological bundle $\lambda \subset p^{\ast }E$; in the real case this is the projectivization of a real vector bundle.

The same construction applies to an algebraic vector bundle over an algebraic variety: local trivializations glue products with projective space. In the lines convention its universal tautological bundle is a line bundle; the alternative projectivization by quotients convention parametrizes one-dimensional quotient spaces. Both conventions give dimension $\dim X+\mathrm{rank}(E)-1$ and a proper morphism to the base.

In algebraic geometry and differential geometry, a projective bundle is a space that parametrizes lines (or higher-dimensional projective subspaces) in a vector bundle. More formally, given a vector bundle \( E \) over a topological space (or algebraic variety) \( X \), the projective bundle associated with \( E \) is denoted by \( \mathbb{P}(E) \) and consists of the projectivization of the fibers of \( E \).