Lemma 4.13: weights on L are ratios of object values #
lem:scalar-object-values (scalar-normalization.tex). For the deck
grading of a scalar mesh category with at most one arrow between two vertices,
a weight d on L gives the automorphism Φ of the cover
(ScalarAutomorphism.lean). "The endpoints of an arrow differ in height by one,
so the entire morphism space between them is spanned by the arrow. Thus
Φ(a) = w(a) a for some w(a) ∈ k*" (wArr). "Comparing coefficients gives
w(σa) w(a) = ν_X" (mesh_compat). "Assign ν_X to t_X. These weights
respect the triangles of K̃. Since this complex is simply connected,
multiplying along walks gives object values ζ_X" (ζ, ζ_arrow).
"Conjugation by these values fixes every arrow and hence every morphism, so Φ
multiplies each morphism X̃ → Ỹ by ζ_Ỹ / ζ_X̃" (Φ_eq_ratio), and on L
this gives d(x, y) = ζ_y / ζ_x (weight_eq_ratio).
Sheets of walks from the basepoint #
The lift of X in sheet h, as a walk class from the basepoint.
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The sheet of a walk class from the basepoint.
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The deck degree of an arrow.
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Arrow lines: the morphisms of the degree of an arrow are its multiples.
The automorphism Φ on arrows and meshes #
Φ(a) = w(a) a: the scalar of Φ on the lift of an arrow in sheet h.
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The deck degree of the translation edge t_x.
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Compatibility at a mesh: w(σa) w(a) = ν_X for every mate pair.
Object values by simple connectivity #
The value ν_X assigned to the translation edge t_X in a sheet.
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The weights on the edges of the lifted complex: w(a) on arrows, ν_X
on translation edges, one on cone edges.
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The weights respect the triangles.
The object values ζ on the lifted vertices.
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w(a) = ζ_{target(a)} / ζ_{source(a)}.
Conjugation by the object values #
Φ on paths: the lift of a path is multiplied by ζ_Ỹ / ζ_X̃.
Conjugation: Φ multiplies each morphism X̃ → Ỹ by ζ_Ỹ / ζ_X̃.
Lemma 4.13: every multiplicative scalar weight on L is a ratio of
object values, d(x, y) = ζ_y / ζ_x on every nonzero morphism line.