Integral lifting of the nonzero-product Leibniz equations (Theorem 9.1(3)) #
thm:integral-partial-lifting(3) and lem:one-sided-path-coefficients
(integral-partial-lifts.tex). The equations eq:partial-leibniz-group are encoded by
IsSol: a coefficient d r for each ray, zero on unshiftable rays, with
d t = ε_L d r + ε_R d s on every nonzero product rs = t with shiftable output.
Deviation: only part (3) is used (cor:zero-supported-coverage), and it is proved directly:
from a solution modulo two we build an integer solution, by the coefficient formulas of the
proof of Theorem 9.1 — the two-sided part from a lift ω of its restriction to the
two-sided rays (the freeness of W_χ, from the induction hypothesis, enters only here),
the coefficients of generating one-sided rays by the first-arrow recursion
(lem:one-sided-path-coefficients, with paths replaced by unique first arrows), canonical
integer lifts X_a, and Y_b read off from the rows (Lemma 9.5).
The first-arrow recursion #
A chosen first arrow (an ordinary left divisor) of a nonidentity ray.
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The rest of a ray after its chosen first arrow.
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The recursion with fuel.
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The coefficient of a generating left-sided ray (eq:one-sided-path-coefficients):
d_r = [p] + X_a for the two-sided prefix p and the first left-sided arrow a.
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The rest after a two-sided first arrow of a generating left-sided ray is generating and left-sided, of smaller degree.
Fuel independence.
The first-arrow recursion.
Lemma 9.4 (lem:one-sided-path-coefficients), product equations with generating
left-sided output: d_t = d_r for a left-sided first factor, d_t = d_r + d_s for a
two-sided one.
Endpoint layers of one-sided rays #
A left-sided ray is a layer of a generating left-sided ray.
Uniqueness of the layer decomposition.
A chosen local generator ray at x.
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The coefficient of a generating right-sided ray, by the last-arrow recursion.
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The integer coefficients (eq:one-sided-path-coefficients,
eq:proper-successor-coefficients): ω on two-sided rays, j[q̂] + d_{r₀} on layers of
generating one-sided rays, zero on unshiftable rays.
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The coefficients are self-dual under A₀ ↦ A₀ᵒᵖ, exchanging X and Y.
Two-sided rays #
A two-sided ray commutes with the local generators.
The local generator is two-sided when its square survives.
ω along local powers of a two-sided ray: [q̂^n u] = n[q̂] + [u].
Theorem 9.1, cases 2 and 3: generating inputs of types B, L.
The last-arrow recursion (the dual of DL_eq).
Lemma 9.4, dual: product equations with generating right-sided output.
A nonidentity factor f of a two-sided t = q̂^n f is two-sided.
ω along local powers on the right.
The coefficient equation of a nondeep return (eq:nondeep-coefficient-row).
Theorem 9.1, case 2, crown rows: generating inputs of types L, R with generating
two-sided output (eq:generating-crown-row, after stripping two-sided prefixes and
suffixes).
Theorem 9.1, cases 2 and 4: generating inputs of types L, R with two-sided output.
A two-sided ray is a layer of a generating two-sided ray.
The coefficient of a local power of a left-sided ray.
ω of a local two-sided ray.
Theorem 9.1, products with left-sided output (cases 1, 2, 3, 5).
Theorem 9.1, products with two-sided output (cases 2, 4, 5).
Theorem 9.1, products with right-sided output (the dual of eq_TL).
The integer coefficients solve all nonzero-product Leibniz equations
(proof of Theorem 9.1, α well defined).
Solutions modulo two #
The equations of a solution for products with left-sided output.
The equations of a solution for products with two-sided output.
The recursion of DL computes any solution modulo two.
A solution along local powers of a left-sided ray: d(q̂^i t₀) = i d(q̂) + d(t₀).
The coefficients reduce to a given solution modulo two on left-sided rays.
The coefficients reduce to a given solution modulo two (βα = id in the proof of
Theorem 9.1).
The equations of a solution for products with right-sided output.
A crown row holds for every solution.
A nondeep row holds modulo two for every solution.
The lift #
The canonical integer lift of the variable X_a.
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The variable Y_b, read off from a row containing it (eq:crown-coefficient-group).
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Theorem 9.1(3) (thm:integral-partial-lifting): every solution modulo two of the
nonzero-product Leibniz equations lifts to an integer solution. The hypothesis hW is the
lifting property of W_χ = W(Q_χ) (free by Lemma 9.2 and the induction hypothesis of
Prop 8.3).