SLIDE 48 General Motivations Construction of gCICY Construction of Sections Redundancies Classifications Physical Applications
Construct Global Sections in M - Example
X = P1 3 −1 P4 2 3
M = P1 3 P4 2
h0(M, OM(−1, 3)) = 15, p1 ∈ H0(A, OA(3, 2)), q1 ∈ H0(M, OM(−1, 3)). p1(x1, x2) = (x0
1)3 P11(x2)+(x0 1)2x1 1 P12(x2)+x0 1(x1 1)2 P13(x2)+(x1 1)3 P14(x2)
q1(x1, x2) = N(x1, x2) D(x1, x2) , ||N|| = [b]+ = (0, 3), ||D|| = [b]− = (1, 0) D(x1, x2) = x0
1.
x0
1 = 0 ⇒ P14(x2) = 0
si := P14(x2) xi
2
x0
1
, i = 0, · · · , 4 5 global sections D(x1, x2) = x0
1 − x1
ti :=
4
P1a(x2) xi
2
x0
1−x1 1
, i = 0, · · · , 4 , D(x1, x2) = x0
1 + x1
ui :=
4
(−1)aP1a(x2) xi
2
x0
1+x1 1
, i = 0, · · · , 4 ,