WebDec 17, 2024 · 4 This proposition states as follows, What confuses me is the last sentence. Notice that the Lemma 1.3 states as follows. We also have the fact that, The pairing Div X × Div X → Z, only depends on the linearly equivalence class. If C and D are nonsingular curves meeting transversally, then C. D = # ( C ∩ D), the number of points of C ∩ D. WebSolving f= 0 then gives y= x2. If both factors are linearly independent, we can assume that a;d6= 0. Thus by a change of variables (replacing ax bywith xand cx dywith y, which …
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WebHartshorne, Chapter 1 Answers to exercises. REB 1994 2.1 ais homogeneous and so de nes a cone in An+1. fvanishes on all the elements of this cone (including 0 as fhas positive degree) so fq 2afor some q>0 by the usual Nullstellensatz. 2.2 (iii) implies (i) is trivial as xd i 2S d. Proof that (i) implies (ii): If Z(a) is empty, then in An+1, Z(a) Web4 You can compute the cohomology via the Koszul resolution. If i: X → P k 2 is the embedding then the triple 0 → O P 2 ( − d) → f O P 2 → i ∗ O X → 0 is exact. So, you can compute H t ( X, O X) = H t ( P k 2, i ∗ O X) using the long exact sequence associated with this triple. Share Cite Improve this answer Follow answered May 31, 2010 at 12:41 hennings hobby shop
Hartshorne Exercise III.4.7 (cohomology of closed subschemes in
WebSep 20, 2024 · I'm solving problems in Hartshorne. I don't know how to solve the following exercise (6.4 of Chapter 1): Let $Y$ be a nonsingular projective curve. Show that every nonconstant rational function $f$ on $Y$ defines a surjective morphism $\phi:Y\rightarrow \mathbb P^1$. I know I can use 6.7 and 6.8 to extend the morphism $f$ to such a $\phi$. WebHartshorne, Chapter 1.4 Answers to exercises. REB 1994 4.1 If f= gon U\V, then the function which is fon Uand gon V is clearly regular. Therefore the union of all open sets … Web3.4 It is enough to show that ˚ 1 is regular near ˚(1 : x 1: : x n), where ˚is the d-uple embedding. But near this point ˚ 1 takes (m 0: : m N) to (m i 0: : m i n) where m i k is the coordinate corresponding to the monomial xd 1 0 x k, and this is a regular map. 3.5 Identify Pnwith its image under the d-uple embedding. Then His the ... lashovee eyelash serum