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hom approach of tensor of type p q #1

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@jjaassoonn jjaassoonn commented Aug 1, 2024

  1. a tensor of type $(p, q)$ is a $k$ linear map $V^{\otimes^q} \to V^{\otimes^p}$.
  2. a $k$-object of type $(p,q)$ is a $k$ vector space $V$ with a tensor $\Phi$ of type $(p, q)$.
  3. a $k$-object morphism between $(V, \Phi) \to (W, \Psi)$ is a $k$ linear map $f$ such that
V^q -f^q-> W^q
  |\Phi             |\Psi
  v                   v
V^p -f^p-> W^p
  1. if $K/k$ is field extension, there is functor from $k$-object to $K$-object sending $(V, \Phi)$ to $(V_K, \Phi_K)$.
  2. if $\sigma \in \mathrm{Gal}(K/k)$ and $f$ is a $K$-morphism between $(V_K, \Phi_K)$ and $(W_K, \Psi_K)$, $\sigma$ induces another $K$-morphism by conjugation

simp only [extendScalars_carrier, ← LinearMap.comp_assoc]
rfl

def inducedByGal (σ : K ≃ₐ[k] K) (f : V.extendScalars K bV ⟶ W.extendScalars K bW) :
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This is the action of $\mathrm{Gal}(K/k)$ on $K$-morphism between $V_K$ and $W_K$

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@Whysoserioushah Whysoserioushah left a comment

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牛啊wk

@Whysoserioushah Whysoserioushah marked this pull request as ready for review October 26, 2024 14:28
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