- #1
Bacle
- 662
- 1
Hi, Everyone:
Sorry if this is too simple: I guess the intersection for for CP^2
(complex projective 2-space) is (-1), right?. Since H_2(CP^2,Z)=Z,
which is represented by CP^1, which has self-intersection=-1.
Then, if we had a connected sum of CP^2's, the intersection form
would be : (-1)(+)(-1)(+)...(+)(-1) ?
And, if we reversed the orientation of CP^2, then we would
substitute a (-1) for a (+1) , right, or do the orientation
changes of the self-intersecting copies of -CP^2 cancel out
to give us a negative self-intersection?
Thanks.
Sorry if this is too simple: I guess the intersection for for CP^2
(complex projective 2-space) is (-1), right?. Since H_2(CP^2,Z)=Z,
which is represented by CP^1, which has self-intersection=-1.
Then, if we had a connected sum of CP^2's, the intersection form
would be : (-1)(+)(-1)(+)...(+)(-1) ?
And, if we reversed the orientation of CP^2, then we would
substitute a (-1) for a (+1) , right, or do the orientation
changes of the self-intersecting copies of -CP^2 cancel out
to give us a negative self-intersection?
Thanks.