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Čech cohomology of twists on the projective line (h0(O(n))=max(n+1,0),h1(O(n))=max(−n−1,0))

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2026-10-14  NaN By others on same topic  0 Discussions Create my own version
On the standard two-affine cover of the projective line, with coordinate t, a frame for the twisting sheaf on projective space O(n) on the second chart equals tn times the frame on the first. Its Čech cochain complex is k[t]⊕k[t−1]→k[t,t−1], with map (a,b)↦tnb−a. The kernel has basis 1,t,…,tn for n≥0. The cokernel has basis tn+1,…,t−1 for n≤−2. The two-chart complex also proves vanishing in degrees at least two.

 Incoming links (4)

  • Past exam of the mathematics course of the University of Cambridge / 2004 / iii / Paper 80 / 3 / Solution
  • Past exam of the mathematics course of the University of Cambridge / 2007 / iii / Paper 23 / 2 / Solution
  • Past exam of the mathematics course of the University of Cambridge / 2007 / iii / Paper 23 / 3 / Solution
  • Residue duality on the projective line

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