Section 11 commutativity: raw second scalar stability bound #
The raw uncollapsed form of the second scalar stability estimate: the counterpart of
MIPRE/Background/LIDT/MIPStarRE/LDT/Commutativity/GCommStability/Scalar/RawSecond.lean in the
port of planning/c6b-plan.md (milestone M7, section "Port conventions").
The raw defect is stated with the placements strategy.state.L and strategy.state.R, and the
two helpers avgOver_right_linear and sum_ev_leftTensor_mul_rightTensor_const take the
symmetric model S where the vendored ones take the state ψ, in the same position. The vendored
hypothesis hnorm : strategy.state.IsNormalized of gCommStabilityTwo_raw_scalar_pointwise_bound
and gCommStabilityTwo_raw_scalar is dropped, as the port conventions drop hψ : ψ.IsNormalized:
the first Cauchy–Schwarz factor is bounded through VecState.ev_one_of_isNormalized, which takes
no hypothesis. Callers omit that argument, which stood between zeta and family.
The proofs are shorter than the vendored ones. Self-adjointness through Matrix.PosSemidef is
IsSelfAdjoint.of_nonneg; the Kronecker computations of the Cauchy–Schwarz factors are the
keystone's conjTranspose_opTensor and opTensor_mul, and their positivity and monotonicity
opTensor_nonneg, opTensor_mono_left and opTensor_mono_right. The inner bound of
gCommStabilityTwo_raw_left_sum_le is the total bound of sandwichByOuterSubMeas, reindexed by
Equiv.prodComm, and avgOver_right_linear pulls the average through the right placement with
ev_opTensor_averageOperatorOverDistribution_right.
Not ported #
Every declaration of the vendored file has a counterpart here.
References #
In LionSR/MIPStarRE at commit 507e8122, not in this repository:
references/ldt-paper/commutativity-G.texblueprint/src/chapter/ch08_commutativity.tex
Averaging over u commutes with the finite sums and passes into the right placement:
E_u ∑_{g,a} ⟨L_{g,a} ⊗ P_a Q_{u,g}⟩ = ∑_{g,a} ⟨L_{g,a} ⊗ P_a (E_u Q_{u,g})⟩.
A finite sum of left placements against a fixed right placement collapses into the left factor.
Raw uncollapsed scalar defect for the paper's second G-commutativity
stability estimate after the right-register point-product swap.
For fixed slice height x, this is the expression from
commutativity-G.tex, clm:g-comm-stability2, before collapsing the
(v,y), b-average into gCommStabilityTwoR. The left register contains
G^x_g B^{v,y}_b (1-G^x), while the right register contains the swapped point
product P^{v,y}_b P^{u,x}_{g(u)}.
Equations
- One or more equations did not get rendered due to their size.
Instances For
The left-register sandwiches of the raw second defect sum to at most 1 - G^x:
∑_{g,b} (1 - G^x) B_b G^x_g B_b (1 - G^x) ≤ 1 - G^x for projective G^x.
Pointwise Cauchy–Schwarz bound for the raw second scalar defect:
|raw defect at x| ≤ √⟨Ψ, (1 - G^x) ⊗ Z^x Ψ⟩.
Raw paper form of the second scalar G-commutativity stability estimate.
This bounds the uncollapsed post-swap defect used in the paper line-87 removal:
the defect still averages over (v,y), u, g, b rather than first packaging the
left-register sandwich as gCommStabilityTwoR. The vendored theorem asks for a normalized
state.