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2 votes
1 answer
268 views

Jacobian fibration of elliptic fibration: basic relations between Enriques invariants

Let $f: X \to B$ be an elliptic fibration, so proper map from smooth surface $X$ onto smooth conn. curve over alg closed base field $k$ with connected fibers such that almost all fibers are elliptic ...
user267839's user avatar
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0 votes
0 answers
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Relative minimal models of pencils of surfaces

I would like to ask for recomendation for literature on theory relative minimal models of surfaces, where "relative" in sense of that the study objects are not surfaces alone (="absolue ...
user267839's user avatar
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2 votes
1 answer
137 views

Contraction of $(-1)$ curve and extremal ray

I want to prove Castelnuovo's contraction theorem by Mori's contraction theorem. Question. How can one show that a $(-1)$ curve on a smooth surface is an extremal ray?
George's user avatar
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2 votes
0 answers
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Reference request The support of $f$-nef divisor

I'm seaching for a proof of the theorem below. Do you know any reference? Consider $f:X\rightarrow Y$ projective birational map between normal varieties and $\mathbb{R}$ cartier divisor $D$ whose ...
George's user avatar
  • 328