The automorphism Φ of the cover induced by a weight #
Lemma 4.13 (lem:scalar-object-values, scalar-normalization.tex):
"Every scalar automorphism consequently fixes each V_X̃ up to isomorphism.
Choose such isomorphisms, using the natural ones on projectives, in the
direction for which the following automorphism agrees with the given scalar
automorphism on the lifted projectives. Full faithfulness in Lemma 4.8 turns
them into an object-fixing automorphism Φ of C̃."
For a weight d on L, each lifted object X̃ gets a d-scaled
automorphism of V_X̃ (ScAut): the natural one m ↦ d(z, x̃) m on a lifted
projective x̃ (natAut), and on the other objects the components of an
isomorphism V_X̃^{σ_d} ≅ V_X̃ over a finite covering algebra containing the
support (exists_twistAut, from weight_twist_iso). Conjugating composition
with f : X̃ → Ỹ by these gives a natural family, hence by Lemma 4.8 a morphism
Φ f (Φ). Φ is linear, multiplicative, injective, and multiplies a
morphism z₁ → z₂ of L by d(z₁, z₂) (Φ_proj).
Semilinear maps of V_X̃ #
A map semilinear for an automorphism, as a k-linear map.
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Scaled automorphisms of V_X̃ #
A d-scaled automorphism of V_X̃.
- ψ : ScFam d X X
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The natural scaled family on a lifted projective: m ↦ c(z, x₀) m.
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The natural automorphism of V_x̃ for a lifted projective x̃.
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Twisted automorphisms #
A finite set of lifted projectives containing the support of V_X̃.
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A weight fixes V_X̃ up to isomorphism: a d-scaled automorphism from
an isomorphism V_X̃^{σ_d} ≅ V_X̃ over a finite covering algebra.
Conjugating composition with f by scaled automorphisms gives a natural
family.
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The chosen automorphisms: natural on the lifted projectives.
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The automorphism Φ of C̃ on a morphism f : X̃ → Ỹ.
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Uniqueness: Φ f is the only morphism with the defining property.
Φ is multiplicative.
Φ is injective.
Φ agrees with the scalar automorphism on L: it multiplies a morphism
x̃₁ → x̃₂ of lifted projectives by d(x̃₁, x̃₂).