# Extention of vector bundles on projective line: $Ext^1({\mathcal O_{\mathbb{P}^1}}(n),{\mathcal O_{\mathbb{P}^1}}(m))=$??

I want to know the value $Ext^1({\mathcal O_{\mathbb{P}^1}}(n),{\mathcal O_{\mathbb{P}^1}}(m))$ for integer m, n.

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Have you considered short exact sequences $0\to\mathcal O_{\mathbb P^1}(m)\to U\to\mathcal O_{\mathbb P^1}(n)\to 0$? – Berci Oct 6 '12 at 8:55

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