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Two instability measures of a subspace o...
Matsushita, Jun-ichi...
Two instability measures of a subspace of $P^{n}(K)$ under a subgroup of $\operatorname{Aut}(K)$ by Matsushita, Jun-ichi ( Author )
Australian National University
08-08-2023
Let $K$ be a commutative field and let $V$ be a subspace of $P^{n}(K)$. Let $\Gamma$ be a subgroup of $\operatorname{Aut}(K)$ and let $\Gamma$ act on $P^{n}(K)$ by $\sigma((x_{i})_{0\leq i\leq n})=(\sigma(x_{i}))_{0\leq i\leq n}$ for $\sigma\in\Gamma$ and $(x_{i})_{0\leq i\leq n}\in P^{n}(K)$. In this paper, we ask `how much' unstable $V$ is under $\Gamma$ by asking how much higher or lower dimension the join and the meet of $\sigma(V)$ ($\sigma \in\Gamma$) have than $V$, and answer it in terms of the Pl\"{u}cker coordinates of $V$ and the invariant field $k$ of $\Gamma$, through presenting two `irrationality' measures of $V$ over $k$.
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Article
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29.34 KB
English
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MYR 0.01
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http://arxiv.org/abs/1603.01349
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