Twisted traces on a star (Lemmas A.2 and A.4) #
lem:twisted-trace-surjection, lem:arm-trace-reduction
(periodic-mesh-calculations.tex). Let π : ℤΔ → Q be a covering of a
star model with signed coefficients, and let (v, t) ↦ (σ v, t + s) be a deck
transformation with σ fixing the centre. In degree d = m + 1 = 2 + s, the row
class of a closed path at a σ-fixed vertex v (phiV) is independent of the
height, kills the relations of Π(Δ), and satisfies twisted rotation.
The row class of a closed path at a σ-fixed vertex, lifted at height h.
Instances For
Twisted rotation in terms of phiV.
Rotation of an initial segment whose vertices are fixed by σ.
The linear extension of phiV.
Instances For
Traces of words at the centre #
The trace of a word w in the x_i: the row class of the closed path at
the centre, in path degree 2 |w| = m + 1, and zero in other degrees.
Instances For
Twisted rotation of words: [u v] = [v θ(u)].
The centre relation ∑ x_i = 0 in traces.
The arm relation x_i^{L_i+1} = 0 in traces.
Arms fixed by the twist (Lemma A.4, second part) #
Closed paths with the same class modulo the relations have the same row class.
Outward backtracks on a fixed arm have zero trace: rotating the first
arrow turns y_r^q into z_{r+1}^q, which the mesh at r + 1 identifies with
y_{r+1}^q, or kills at the leaf.
[x_i^q] = 0 on an arm fixed by the twist (eq:arm-power-trace-zero).