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Dec 18, 2011 at 19:28 comment added diverietti So, where is Angelo's answer incorrect? I cannot see!
Dec 16, 2011 at 10:33 comment added Parsa If the assumption is that for any $x,y \in X$ there is a global section such that it vanishes at $x$ and doesn't vanish at $y$, OR vice versa, then this system is not necessarily ample.
Dec 14, 2011 at 14:58 vote accept diverietti
Dec 14, 2011 at 14:38 comment added Angelo I have no idea how to give a direct elementary proof, sorry.
Dec 14, 2011 at 14:36 history edited Angelo CC BY-SA 3.0
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Dec 14, 2011 at 14:17 comment added diverietti I didn't say that in the original question, but I was really guessing if there was a "down-to-earth proof" of this fact...
Dec 14, 2011 at 14:16 comment added diverietti Dear Angelo, thank you very much for your answer! As long as I can see, it seems to work perfectly. Two comments are in order: 1) Which "kind" of GAGA are you invoking here? Does one need $X$ to be already projective in order to say that a line bundle on $X$ pullback of an ample by a finite map is ample? 2) Do you think there is a more "elementary" proof of this fact? By elementary I mean just using, for example, combining sections of different powers of $L$ to obtain such an uniformity (I don't know if I am clear enough to make you understand what I mean by elementary here...)
Dec 14, 2011 at 13:58 history answered Angelo CC BY-SA 3.0