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3 votes
0 answers
452 views

Singularities of rational quartic surfaces

Let $X\subset \mathbb{P}^3$ be an irreducible quartic surface, defined over an algebraically closed field $k$. Suppose that $X$ is rational (i.e. birational to $\mathbb{P}^2$). Is is true that $X$ has ...
Jérémy Blanc's user avatar
4 votes
1 answer
327 views

Singularities of fibrations

Let $f:X\rightarrow \mathbb{P}^2$ be a fibration, here $X$ is a projective variety of dimension three. Assume that there exixts a smooth curve $C\subset\mathbb{P}^2$ such that for any $p\in\mathbb{P}...
Puzzled's user avatar
  • 8,998
2 votes
1 answer
167 views

Singularities of $3$-folds

Let $X,Y,Z$ be projective $3$-folds. Assume that $Y$ is smooth and $Z$ is smooth and Fano. Moreover, assume that there is a generically finite morphism $f:Y\rightarrow Z$ admitting a factorization $f=...
user avatar
3 votes
0 answers
82 views

Singularities of fibrations 2

This question is related to my previous question: Singularities of fibrations Assume that $X$ is a complete intersection irreducible $3$-fold in a product of projective spaces. So that $X$ is ...
Puzzled's user avatar
  • 8,998