New posts in projective-space

When is the restriction of a quotient map $p : X \to Y$ to a retract of $X$ again a quotient map?

Distance between line and point in homogeneous coordinates?

How is the metric defined on the real projective space $\mathbb{RP}^n$?

What is topological distortion?

Show compactification of positive real plane is homeomorphic to $\Bbb R \Bbb P^2$

Why are there no non-trivial regular maps $\mathbb{P}^n \to \mathbb{P}^m$ when $n > m$?

Why does the projection $\pi:(a,b,c) \in S^2 \to[a,b,c] \in P^2$ have rank 2 everywhere?

Cross-ratio relations

integral cohomology ring of real projective space

How to show $P^1\times P^1$ (as projective variety by Segre embedding) is not isomorphic to $P^2$?

What is the difference between projective geometry and affine geometry?

Finding a non-degenerated quadric containing three projective lines in $\mathbb{P}^3(\mathbb{C})$

Orientability of projective space

No map $\mathbb{C}P^n \rightarrow \mathbb{C}P^m$ inducing a nontrivial map $H^2(\mathbb{C}P^m;\mathbb{Z}) \rightarrow H^2(\mathbb{C}P^n;\mathbb{Z})$

The trace as an integral over the projective space

The cross-ratio of four points is a real number exactly when the four points lie on a line or a circle

proving a result in (elementary) planar projective geometry about cross ratios

Does there exist a regular map $\mathbb{A}^1\to\mathbb{P}^1$ which is surjective?

Lines in projective space

Acting on CP(2) by conjugation