LMN

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Name	LMN
Member for	10 months
Seen	May 7 at 2:24
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I like to ask questions here to learn things that are sometimes hard to learn from books.

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Apr 9	comment	Additive functors and Derived Categories Thanks for you comments Sasha!
Apr 9	comment	Additive functors and Derived Categories Sasha, so it seems like #1 isn't mainstream. Is that right?
Apr 9	asked	Commutativity of Tor
Mar 27	comment	Prorepresentable functors repres. by alg. spaces? Covering spaces by alg. spaces. Thanks Dan! This is interesting.
Mar 27	asked	Prorepresentable functors repres. by alg. spaces? Covering spaces by alg. spaces.
Mar 18	asked	Representability of sheaves of groups
Mar 1	comment	Absorbing ramification and factoring finite flat maps @Qing: Thanks !
Feb 23	comment	Betti numbers of Proper nonprojective varieties anon, sorry to be silly - but since this isn't my area I just want to make sure. When you speaks of betti numbers in characteristic $p$, you referring to the algebraic de Rham complex?
Feb 23	comment	Betti numbers of Proper nonprojective varieties Thanks Dmitri, Donu. This is very helpful!
Feb 23	comment	Betti numbers of Proper nonprojective varieties No problem :)
Feb 23	revised	Betti numbers of Proper nonprojective varieties added 215 characters in body; added 7 characters in body; deleted 44 characters in body
Feb 23	asked	Betti numbers of Proper nonprojective varieties
Feb 22	comment	Understanding Adjointness of Sheaves in Algebraic Geometry @ayanta, no problem, and Thanks for your comments!
Feb 22	awarded	● Nice Question
Feb 22	comment	Understanding Adjointness of Sheaves in Algebraic Geometry Thanks Donu!
Feb 22	comment	Understanding Adjointness of Sheaves in Algebraic Geometry Sasha, Thanks !
Feb 22	comment	Understanding Adjointness of Sheaves in Algebraic Geometry ayanta, I'm asking for something a little different, I already worked out a proof for myself. You're of course right, the proof splits up as you say :)
Feb 22	asked	Understanding Adjointness of Sheaves in Algebraic Geometry
Feb 21	comment	Topologically embedding curves in Jacobian Thanks Davidc897, and thanks everyone for your great answers!
Feb 21	comment	Topologically embedding curves in Jacobian Ah, yes. Thanks Eric.
Feb 21	revised	Topologically embedding curves in Jacobian added 109 characters in body
Feb 21	revised	Topologically embedding curves in Jacobian added 23 characters in body
Feb 21	asked	Topologically embedding curves in Jacobian
Feb 3	comment	Determing Hodges Maps by their Essential Algebraic Properties John, I'm just trying to understand the question. When you say "Hodge map" are you explicitly referring to the hodge star operator? I'm a little confused, since you say the plural "Hodge maps" later (which makes sense in this context). I'm just being a little careful. Is this standard terminology?
Jan 30	comment	Hodge numbers of reduction mod $p$ @Emerton: Thanks!
Jan 26	comment	Absorbing ramification and factoring finite flat maps @Will, no problem :)
Jan 26	revised	Absorbing ramification and factoring finite flat maps edited body
Jan 26	comment	Absorbing ramification and factoring finite flat maps @Scott, thanks - I made the correction.
Jan 26	comment	Absorbing ramification and factoring finite flat maps @Keerthi, Ray, Thanks! I'll look into it. Will, I don't understand, could you clarify please? The picture I have in mind is what you say - I'm taking finite flat maps and absorbing their ramification to become etale.
Jan 25	comment	Absorbing ramification and factoring finite flat maps Can someone tell me if the link to google books is visible to them? I could write up the theorem, but since mathoverflow doesn't really support commutative diagrams it won't look nearly as good as the version in Beauville's book.
Jan 25	revised	Absorbing ramification and factoring finite flat maps added 1 characters in body
Jan 25	revised	Absorbing ramification and factoring finite flat maps clarification; edited tags
Jan 25	asked	Absorbing ramification and factoring finite flat maps
Jan 25	comment	Complement to an open affine subvariety in an irreducible projective one This completes the proof (for the last statement, I'm using an exercises from Hartshorne; that if one removes a point of codimension $\ge 2$ from a normal affine scheme the result is not affine.)
Jan 25	comment	Complement to an open affine subvariety in an irreducible projective one agleearner, I can sketch the proof: (1: Thm, An arbitrary morphism from an affine scheme to a separated scheme is affine, see mathoverflow.net/questions/74806/… for a sketch of proof). Now, let $U \subset X$ an affine open set, $Y = X - U$ and $y$ a generic point of a component of $Y$. The map $\phi: Spec \mathcal{O}_{X,y} \rightarrow X$ is affine by thm. above, hence $\phi^{-1}(U) = Spec \mathcal{O}_{X,y} - \{y\}$ is affine. Since $X$ is normal, it follows that the dimension of this local ring is $1$.
Jan 25	accepted	Complement to an open affine subvariety in an irreducible projective one
Jan 24	awarded	● Organizer
Jan 24	comment	Universal property of blowing down ...glad to know I wasn't totally wrong for being confused. (In any case, I'm always very appreciative for your comments Jason!)
Jan 24	answered	Complement to an open affine subvariety in an irreducible projective one
Jan 24	comment	Universal property of blowing down ...it also applies to essentially arbitrary blowups of normal, noeth. integral schemes.
Jan 24	comment	Universal property of blowing down @pranavak, thanks. It's interesting that the required condition remains "to be constant along the fibers" - something checked purely at the level of topological spaces. It's even incredibly more general than just blowing up. It applies to any of the morphisms (with connected fibers) coming from stein factorization.
Jan 23	comment	Universal property of blowing down Allen, that's hilarious :) thanks for pointing it out, and thanks for your comment.
Jan 23	revised	Universal property of blowing down edited title
Jan 23	revised	Universal property of blowing down added 175 characters in body; added 1 characters in body
Jan 23	asked	Universal property of blowing down
Jan 14	awarded	● Teacher
Jan 14	accepted	On the blow-up along the diagonal in a product
Jan 13	revised	On the blow-up along the diagonal in a product deleted 4 characters in body
Jan 13	answered	On the blow-up along the diagonal in a product
Jan 12	comment	Primitive Cohomology Useful? I moved my follow up question (the parts on Computing and Functoriality) here to have everything in one place.

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