# MathSciDoc: An Archive for Mathematician ∫

#### Complex Variables and Complex Analysismathscidoc:1910.43796

Proceedings of the American Mathematical Society, 121, (3), 859-864, 1994
It is proved that if the twistor space of a self-dual four-manifold of positive scalar curvature contains a real effective divisor of degree two, then the four-manifold is diffeomorphic to the connected sum n\mathbb {C}{P^ 2} of n complex projective planes for some n. It follows that if the four-manifold is known to be homeomorphic to n\mathbb {C}{P^ 2} , then it is also diffeomorphic to n\mathbb {C}{P^ 2} .
```@inproceedings{henrik1994self-duality,
title={Self-duality and differentiable structures on the connected sum of complex projective planes},
author={Henrik Pedersen, and Yat Sun Poon},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20191020220515357042325},
booktitle={Proceedings of the American Mathematical Society},
volume={121},
number={3},
pages={859-864},
year={1994},
}
```
Henrik Pedersen, and Yat Sun Poon. Self-duality and differentiable structures on the connected sum of complex projective planes. 1994. Vol. 121. In Proceedings of the American Mathematical Society. pp.859-864. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20191020220515357042325.