Cycle witnesses at every order, incompatibility and distance #
AUDIT-NOTES A5 / Theorem thm:cycle: the parity witness cycle_witness (from
CycleWitness.lean), the incompatibility of the cycle target (cycle_not_compatible) and
the distance bound q/10 ≤ d_TV (cycle_distance), the last two through the quantitative
parity rigidity CycleModelAux.quant_rigidity (Lemma lem:quantrigidity). Everything here
is proved.
AUDIT-NOTES A5, the cycle witness. With N = mt auxiliary signs s_{v,i} carrying the
positive density H_{N,q}(s) = 2^{−N} ∑_{|S| even} (−q)^{|S|/2} ∏_S s, and copied
observations O_v^{ij} = s_{v−1,i} s_{v,j}, the target P_{m,q} with moments
(−q)^{|∂F|/2} passes every AI prescription at order t, for q = 1/(4m²t²): the
boundaries of ancestrally disjoint injectable blocks are disjoint, so their moments
multiply.
The same witness passes the recursively expressible test, by AUDIT-NOTES A2.
Auxiliary material for the cycle arcs #
Nothing in this namespace changes the two statements below, which appear in their original form.
Weighted average of a function over a finite latent alphabet.
Equations
- TriangleInflation.Graph.CycleModelAux.av μ f = ∑ x : X, μ x * f x
Instances For
Quantitative parity rigidity for the triangle pattern.
The edge of the cycle recorded by its lower endpoint.
Equations
Instances For
The three arcs {0}, {1} and {2,…,m-1} #
The vertex 0 of the cycle.
Equations
- TriangleInflation.Graph.CycleModelAux.cv0 m hm = ⟨0, ⋯⟩
Instances For
The vertex 1 of the cycle.
Equations
- TriangleInflation.Graph.CycleModelAux.cv1 m hm = ⟨1, ⋯⟩
Instances For
The vertex m-1 of the cycle.
Equations
- TriangleInflation.Graph.CycleModelAux.cvl m hm = ⟨m - 1, ⋯⟩
Instances For
The boundaries of the three arcs #
Re-randomization in the average form #
The Walsh moments of a model of the cycle #
Reduction of a model to the triangle pattern #
Two sources eX, eY and three groups of vertices: v0, which does not see eY; v1,
which sees only eX and eY; and a block S, no vertex of which sees eX.
The cycle case of the reduction #
Transfer of moments along total variation #
The compatible set is nonempty #
AUDIT-NOTES A5, incompatibility of the cycle target. Partition the cycle into three
nonempty contiguous arcs and output the product of the signs in each arc: a compatible cycle
law induces a compatible triangle law, parity-perfect, whose three means are all -q, and
(-q)^3 < 0 contradicts parity_rigidity. (The proof below uses the quantitative form
CycleModelAux.quant_rigidity of rigidity, which subsumes the exact one.)
AUDIT-NOTES A5, the quantitative form: parity repair (a compatible law with parity error
η is within 5η of a parity-perfect compatible law) turns the rigidity contradiction into
d_TV(P_{m,q}, C_{C_m}) ≥ q/12. The proof below replaces the repair construction by the
moment form CycleModelAux.quant_rigidity, which gives the sharper constant q/10; the
hypothesis m² q ≤ 1/4 (which makes cycleTarget a law) is not needed for the bound.