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Schubert2 :: exceptionalDivisor

exceptionalDivisor -- get the exceptional divisor of a blowup

Synopsis

Description

i1 : T = projectiveSpace 2

o1 = T

o1 : a flag bundle with ranks {1, 2}
i2 : S = projectiveSpace 0

o2 = S

o2 : a flag bundle with ranks {1, 0}
i3 : i = map(T,S,OO_S) -- inclusion of a point in P^2

o3 = i

o3 : a map to T from S
i4 : X = first blowup(i)

o4 = X

o4 : an abstract variety of dimension 2
i5 : exceptionalDivisor X

o5 = a sheaf

o5 : an abstract sheaf of rank 1 on X
i6 : chern oo

o6 = 1 + E
          0

            QQ[][h, H   , H   ]
                     2,1   2,2
     ---------------------------------[E ]
     (h + H   , h*H    + H   , h*H   )  0
           2,1     2,1    2,2     2,2
o6 : -------------------------------------
                        2
              (H   E , E  + H   )
                2,1 0   0    2,2

See also

Ways to use exceptionalDivisor :