Principal parts on the projective line over arbitrary rings (Q946494)

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Principal parts on the projective line over arbitrary rings
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    Principal parts on the projective line over arbitrary rings (English)
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    23 September 2008
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    Let \(F\) be any field of characteristic \(0\) and consider the projective line \(\mathbb P=\mathbb P^1_F\). Call \(\mathcal P^k(\mathcal O(n))\) (\(\mathcal O=\mathcal O_\mathbb P\)) the \(k\)-th sheaf of principal parts on \(\mathbb P\). \(\mathcal P^k(\mathcal O(n))\) has a natural structure of left and right \(\mathcal O\)-module, and it is locally free, of rank \(k+1\). The author works on a trivialization of \(\mathcal P^k(\mathcal O(n))\) and its transition functions, to determine the splitting type as a left and a right module. It turns out that, as a right module, \(\mathcal P^k(\mathcal O(n))^{right}\) is isomorphic to \(\mathcal O(n)\oplus \mathcal O(n-k-1)^k\), while as a left module, \(\mathcal P^k(\mathcal O(n))^{left}\) is either isomorphic to \(\mathcal O^{n+1}\oplus \mathcal O(-k-1)^{k-n}\), when \(0\leq n<k\), or it is isomorphic to \(\mathcal O(n-k)^{k+1}\), in the other cases.
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    Principal parts
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