# Line bundle O(D) on a threefold.
>
> variety(X,dim=3,tan=sheaf(3,[-K,c2,c3])): # traditionally, -K is
> # used instead of c1
i1 : X = abstractVariety(3,QQ[K,c_2,c_3, Degrees => {1..3}][D,Join=>false])
o1 = X
o1 : an abstract variety of dimension 3
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i2 : X.TangentBundle = abstractSheaf(X,Rank=>3,ChernClass=>1-K+c_2+c_3)
o2 = a sheaf
o2 : an abstract sheaf of rank 3 on X
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> chi(o(D));
3 2 2
integral(X, 1/6 D - 1/4 K D + (1/12 K + 1/12 c2) D - 1/24 K c2)
i3 : chi OO(D)
1 3 1 2 1 2 1 1
o3 = integral(-D - -K*D + (--K + --c )D - --K*c )
6 4 12 12 2 24 2
o3 : Expression of class Adjacent
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