IMeasy
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Registered User
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May 18 |
comment |
Proving a variety is not unirational I think that if you find out you can put out a very good paper! |
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May 15 |
answered | blow-ups of secant varieties |
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May 8 |
asked | regularity of finite flat branched covers |
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May 4 |
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Analogue of Knudsen clutching BTW, what is Knudsen clutching? this may help |
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Apr 27 |
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canonical model of a reducible curve thank you to both! |
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Apr 26 |
revised |
canonical model of a reducible curve added 571 characters in body |
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Apr 26 |
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canonical model of a reducible curve thank you for answering. yes in fact that was my suspect but I didn't find a proper reference. I guess that the canonical model of a stable reducible curve is obtained via the global sections of the dualizing sheaf. On the other hand I was wondering wether the definition of the dualizing sheaf (I added this to the quesiton and edited) ha some sort of "functorial" behaviour. That is: to what extent the restriction of the dualizing sheaf of the global curve to a component can be described as the dualizing sheaf (possibly twisted by $\mathcal{O}(p)$, if I recall properly) of that component |
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Apr 26 |
revised |
canonical model of a reducible curve edited tags |
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Apr 26 |
asked | canonical model of a reducible curve |
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Apr 23 |
asked | state of the art for kodaira dimension of $\overline{\mathcal{M}}_{g,n}$ |
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Apr 22 |
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smooth modular compactification of moduli of curves for exemple here arxiv.org/abs/math/0601251 there should be also a compactification for the event theta by van der geer (math ann in the 80s) but I can't rememeber if it is smooth |
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Apr 18 |
answered | hyperelliptic stable genus four curve |
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Apr 18 |
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hyperelliptic stable genus four curve ok, that's right |
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Apr 18 |
answered | Albanese dual to the Picard scheme |
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Apr 16 |
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Are these two definitions of $\mathcal{O}(1)$ over a ruled surface closely related? It is, you just plug any element of $E$ in the tensor $\wedge^2 E^*$ and get $E^*$. End of the proof. |
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Apr 16 |
answered | smooth modular compactification of moduli of curves |
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Apr 16 |
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hyperelliptic stable genus four curve There's something I don't understand. If you say $\mathfrak{g}^1_3$ it means a linear system of dimension 1 and degree 3, so $h^0=2$. Probably you should re-write the question. As it stands it is difficult to understand what you want. |
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Apr 16 |
revised |
lifts of maps to $\mathcal{M}_{1,1}$ added 254 characters in body |
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Apr 16 |
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lifts of maps to $\mathcal{M}_{1,1}$ ah sorry, I think I see what you mean. let me edit the question. |
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Apr 16 |
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lifts of maps to $\mathcal{M}_{1,1}$ generically - I agree - is a Z_2 - gerbe, but there are elliptic curves with bigger automorphism group, no? and I want to consider all smooth elliptic curves |
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Apr 16 |
asked | lifts of maps to $\mathcal{M}_{1,1}$ |
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Apr 12 |
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13 months and not even one report. what would you do? Indeed it is! I asked what was the right thing to do, and then I decided to wait and see. The result is that finally I've had my positive report. Hence I would say this is the right answer. :) |
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Apr 12 |
awarded | ● Self-Learner |
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Apr 12 |
answered | 13 months and not even one report. what would you do? |
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Apr 11 |
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universal families and maps to quotient stacks Yes, I should have said canonical. Universal has a categorical meaning which is not true here. Thank you! |
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Apr 11 |
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universal families and maps to quotient stacks But I still don't understand one thing. By pulling back the universal family from $[X//G]$ to $X$, don't I get a "universal" $G$-invariant family on $X$? |
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Apr 11 |
revised |
universal families and maps to quotient stacks added 5 characters in body |
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Apr 11 |
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universal families and maps to quotient stacks Ok let's say that I composed with a forgetful functor $f: Groupoids \to Sets$.... :) Just kidding, it is a good remark, I edited. That's more or less what I felt: that I can lift the map $S$-globally iff the torsor $X \to [X//G]$ is trivial over the image of $S$. |
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Apr 11 |
asked | universal families and maps to quotient stacks |
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Apr 11 |
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Strong notions of general position On the other hand, a conic ("circle") always passes through 4 general (in the linear sense) poins of a projective plane... |
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Mar 29 |
revised |
is the orthogonal complement of a saturated sequence saturated? edited title |
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Mar 29 |
asked | is the orthogonal complement of a saturated sequence saturated? |
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Mar 18 |
asked | Hurwitz’s construction of simple covers |
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Mar 15 |
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one “big” Hilbert scheme? welll yes.... it is actually what I meant! |
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Mar 12 |
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Quotient of trivial bundles At least in the algebraic setting, I feel like the quotient is always a trivial bundle because a map between two trivial bundles is just a vector of scalars... |
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Mar 10 |
awarded | ● Nice Question |
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Mar 10 |
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“Degree” of an algebraic variety yeah, maybe a Bezout-like theorem |
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Mar 9 |
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one “big” Hilbert scheme? Hey put your comment in an answer so that I validate it! |
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Mar 9 |
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one “big” Hilbert scheme? don't take me bad... but, to obtain a Hilbert scheme, doesn't one need to fix the Hilbert polynomial? The Hilb-scheme parametrizing all subchemes is just the disjoint union of the different Hilb-schemes? |
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Mar 9 |
asked | one “big” Hilbert scheme? |
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Mar 6 |
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what are mutations of sheaves all about? yes, that's exactly the only case where I saw some geometry going on. My idea was: maybe if I mutate (R or L) a sheaf w.r.t. a second sheaf I can say something more about the mutated sheaf... but I don't really see how. |
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Mar 6 |
asked | what are mutations of sheaves all about? |
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Feb 19 |
awarded | ● Yearling |
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Feb 15 |
awarded | ● Enthusiast |
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Feb 11 |
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examples of moduli functors for which coarse moduli space does not exists @Brenin: no problem, it is a cute example! |
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Feb 10 |
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does there exist a family of objects over the tangent space to the base space of a family of objects? Thank you, Allen. I don't fully understand what you mean by $\Xi_p$, is it the full fiber over $p$, right? |
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Feb 10 |
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examples of moduli functors for which coarse moduli space does not exists Classifying space: you mean a scheme that parametrizes the whole thing? Like $\mathbb{P}^5 - Ven_2(\mathbb{P}^2)$ in your case. |
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Feb 10 |
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Projective submanifolds of $\mathbb CP^n$ whose normals bundles are sums of linear. Of course you are right. I am sorry I didn't notice that you assumed the smootheness of the variety. As it is now my comment means nothing. I will delete it in the next few days. ;) |
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Feb 9 |
answered | Projective submanifolds of $\mathbb CP^n$ whose normals bundles are sums of linear. |
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Feb 9 |
asked | examples of moduli functors for which coarse moduli space does not exists |
