Weights in a cone (toward Proposition 12.8) #
deformation-refinements.tex: "For each bar differential choose a k-linear right
inverse on its image; […] Make these choices separately in each degree and weight". In the family
m + Σ_i t_i μ_i the parameter t_i carries the weight χ_i of μ_i, so the lifts are
homogeneous when every component has relative weight in the monoid C spanned by the χ_i.
For a weight grading G and σ, ConeAt C σ n says that the components of n have weights in
σ + C, and cpart C σ projects onto them. Maps shifting weights by γ move σ + C to
σ + γ + C (ConeAt.shift); maps and bilinear maps whose components have relative weights in C
(ConeLin, ConeBil) preserve the cone condition, and their cone parts are clin, cbil.
Shifting maps move the cone.
Shifting maps commute with the cone parts.
Maps with relative weights in the cone #
The components of f have relative weights in ρ + C.
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The components of φ have relative weights in ρ + C.
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A cone condition on the input propagates.
The cone part of a linear map relative to ρ.
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The cone part of a bilinear map relative to ρ.
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Bilinear maps agreeing on homogeneous elements agree.
Bottom components in a pointed cone #
Only the bottom component of the input reaches the bottom component of the output.
Cone conditions on maps: closure properties and bottom parts #
A map whose relative weights lie in γ + C with γ ≠ 0 has no bottom part.
The bottom part of a composite is the composite of the bottom parts.
Components at an atom of the cone #
Atom components of a linear image: only the bottom and the atom component of the input contribute to the atom component of the output.
Atom components of a bilinear image.