MP
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Registered User
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2h |
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open immersion between affine spaces Take a look at the the Ax-Grothendieck theorem! |
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May 5 |
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zeta(3) in terms of derivatives of zeta at 1/2 and pi In the question, the result is checked to $10^4$ digits, which seems more precision that 500! |
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Apr 29 |
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Enriques classification of algebraic surfaces The second question seems easier. The assertions $K$ nef and $K^2=0$ imply that if a multiple of $K$ moves, then it maps to a curve. Combining this with the inequality on the 12th plurigenus gives you the result. I am not sure how to proceed in the other case: you would need to know something similar to $K^2=0$ to proceed in a similar way. |
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Apr 26 |
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Noether-Lefschetz over finite fields (Though let me add that the Picard number over the ground field might be odd, so you could refine the question.) |
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Apr 26 |
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Noether-Lefschetz over finite fields K3 surfaces over finite fields have (geometrically) even Picard number: not much hope for Noether-Lefschetz for quartic surfaces! |
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Apr 25 |
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Gauss mapping in finite characteristic You can start reading here: link.springer.com/article/… |
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Mar 31 |
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Simple field extension and rational points @wccanard: you have interpreted my comment correctly, and I was wrong! |
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Mar 31 |
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Simple field extension and rational points $x^p+sy^p+tz^p \in \mathbb{F}_p(s,t)[x,y,z]$? |
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Mar 8 |
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Kodaira dimension of symmetric products of curves If the Jacobian of the curve is simple, then all its proper subvarieties are of general type; in particular the symmetric product of the curve is of general type, until the Abel-Jacobi map is surjective. By deformation, I would guess that the same is true for all curves, not just the ones that have simple Jacobian. |
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Feb 14 |
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Resolution of singularities of this cubic surface? It seems that your surface the Cayley cubic: there are a lot of interpretations of the Cayley cubic! |
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Feb 3 |
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Rational groups Ok, now I see why my example is not a counterexample! |
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Feb 3 |
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Rational groups Btw, possibly I am confused: is your $g$ in the normalizer/centralizer formula an $x$? Also, by a $p$-element do you mean an element of order $p$ or of order a power of $p$? |
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Feb 3 |
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Rational groups Isn't $Z/4$ a counterexample? |
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Jan 18 |
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When is a smooth projective variety a fibration mathoverflow.net/questions/35429/… |
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Jan 4 |
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Lines on degree 2n-3 Fermat hypersufaces The Fermat threefolds contain several one-parameter families of lines: partition the variables into two sets of size 2 and 3 and set them separately to zero. You obtain $10d$ families of lines in this way. Of I recall correctly, these are "non-reduced" as soon as $d$ is at least 5. You can find out more in papers by Albano-Katz and more recently Candelas and others. |
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Jan 1 |
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What is a random number? (poll experiment) psycnet.apa.org/… |
