chi(AbstractSheaf) -- compute the Euler characteristic of an abstract sheaf

i1 : X = abstractProjectiveSpace' 2

o1 = X

o1 : a flag bundle with subquotient ranks {2, 1}

i2 : chi OO_X(-1), chi OO_X(0), chi OO_X(1), chi OO_X(2), chi OO_X(3)

o2 = (0, 1, 3, 6, 10)

o2 : Sequence

i3 : Y = abstractProjectiveSpace'(2, base n)

o3 = Y

o3 : a flag bundle with subquotient ranks {2, 1}

i4 : chi OO_Y(n)

     1 2   3
o4 = -n  + -n + 1
     2     2

o4 : QQ[n]