113 of 263 blocks of the round 2 manuscript are new or changed since round 1; 65 of 215 blocks of round 1 no longer appear. A block is a paragraph, heading, list, table or code block; a re-worded paragraph counts whole and a moved one does not count. This compares the two submitted texts and is not the response letter.
New or changed blocks
[under "Geometric stability and observable inference in dual Koopman–von Neumann embeddings: Corrections and reproducible counterexamples"]
28 October 2026 · Version 1.1.0
[under "Abstract"]
We examine version 2 of arXiv:2609.28999, which reconstructs conservative nonlinear ordinary differential equations from means of transported probability densities. The printed geometric-distortion definition retains the initial separation between neighboring states while its Taylor expansion omits that separation. For the stated directional transport maps, the resulting normalized quantity is at least one, so it cannot satisfy the proposed small-distortion criterion as written. We give a corrected displacement definition and a local derivative estimate, without asserting a universal replacement stability threshold. Applying the standard circular-mean description to the source’s phase-reference circuit shows that finite variance can reduce contrast without shifting the maximizing reference. An explicit pair of positive grid distributions has identical fringes but different arithmetic means, including in a conservative transported-density realization. Further corrections distinguish Bernoulli-ancilla sampling from direct coordinate sampling, reconcile the Lotka–Volterra benchmark parameter with the source definitions, and exhibit a twice continuously differentiable observable for which a stated fourth-order Gaussian remainder fails. All numerical examples are deterministic classical computations with analytic checks and a recorded execution log. These results repair specific geometric, inference, and regularity statements; they do not refute Koopman embeddings, the genuine nonlinear mean-trajectory discrepancy, or all covariance-based error estimates.
[under "1. Introduction and scope"]
The present note concerns statements that can be checked independently of a large-scale quantum implementation. Its main contributions are: (i) an exact initial-separation obstruction to the geometric criterion printed in source Eqs. (30)–(31); (ii) an explicit nonidentifiability construction for the proposed reference-phase readout and a correction to its contrast-to-phase substitution; and (iii) reproducible corrections to sampling prefactors, a benchmark calibration, and regularity assumptions. Each correction is local to the statement identified. Standard ingredients such as Taylor’s theorem, characteristic functions, and quantum amplitude estimation are credited rather than presented as new general theory.
[under "Proof"]
Thus the approximately $0.1$ condition printed in source Eq. (31) cannot hold under the directional-map interpretation given in its geometric discussion. If the intended map were instead the complete flow, the time-zero contradiction in (3) would still remain: the normalized raw separation tends to $1$, rather than $0$, as $h\to0$. The following nonlinear example also gives an all-$h$ obstruction for the complete-flow interpretation, rather than only a time-zero objection.
[under "Proof"]
Then $\dot q=\partial_pH$, $\dot p=-\partial_qH$, and $\Phi_h(q,p)=(q+h\sin(2\pi p),p)$. Both own-coordinate derivatives vanish. Here the complete flow equals the sole nonidentity directional factor exactly; the other factor is the identity. Thus (5) applies to both interpretations for every admissible $h$. A packet with means $(1/2,1/2)$ and a $p$ marginal symmetric about $1/2$ has $\mathbb E\!\left[\sin(2\pi P)\right]=0$. Its mean therefore remains at the fixed-point trajectory $(1/2,1/2)$, exactly, on any interval without coordinate wrapping. A smooth compactly supported symmetric packet can ensure this condition. The printed geometric condition nevertheless fails. This example concerns the geometric condition; its covariance need not remain constant, and no constant-covariance error theorem is invoked.
[under "3.2 A width-uniform complete-flow remainder"]
### 3.2 A width-uniform complete-flow remainder
[under "3.2 A width-uniform complete-flow remainder"]
The remainder for a complete flow can be bounded uniformly as the packet width shrinks. A bound on two separate trajectory remainders would give a loose $O(h^2/\sigma)$ estimate after normalization. Keeping their difference inside the integral instead gives the following standard auxiliary ODE estimate. It concerns the exact complete flow, rather than a global error theorem for a Trotter approximation.
[under "Proposition 3.3: Complete-flow increment bound"]
#### Proposition 3.3: Complete-flow increment bound
[under "Proposition 3.3: Complete-flow increment bound"]
Let $U\subset\mathbb R^d$ be open and convex, and let $F\in C^2(U;\mathbb R^d)$. Suppose $B(x,\sigma)\subset U$, $\sigma>0$, and all trajectories starting in that ball remain in $U$ for $0\leq t\leq h_0$. Assume the uniform bounds
[under "Proposition 3.3: Complete-flow increment bound"]
$$
\sup_U\left\lVert F\right\rVert_2\leq M,\qquad
\sup_U\left\lVert DF\right\rVert_{\rm op}\leq J,\qquad
\sup_U\left\lVert D^2F\right\rVert_{\rm bil}\leq H_{\rm v},\qquad
K:=H_{\rm v}M+J^2,\qquad\text{(11)}
$$
[under "Proposition 3.3: Complete-flow increment bound"]
where $\left\lVert D^2F\right\rVert_{\rm bil}$ is the operator norm of the vector-valued bilinear map $(u,v)\mapsto D^2F[u,v]$. Put $A_h(z)=\Phi_h(z)-z$ and
[under "Proposition 3.3: Complete-flow increment bound"]
$$
R_h(x,\delta):=A_h(x+\delta)-A_h(x)
-h\bigl(F(x+\delta)-F(x)\bigr).\qquad\text{(12)}
$$
[under "Proposition 3.3: Complete-flow increment bound"]
Then, for $0\leq h\leq h_0$ and $\left\lVert \delta\right\rVert_2\leq\sigma$,
[under "Proposition 3.3: Complete-flow increment bound"]
$$
\left\lVert R_h(x,\delta)\right\rVert_2
\leq \frac{K h^2e^{Jh}}{2}\left\lVert \delta\right\rVert_2.\qquad\text{(13)}
$$
[under "Proposition 3.3: Complete-flow increment bound"]
Consequently, writing $H_i=\sup_{B(x,\sigma)}\left\lVert D^2F_i\right\rVert_{\rm op}$, the complete-flow increment statistic satisfies
…and 98 more blocks not shown.Removed blocks
[under "Geometric stability and observable inference in dual Koopman–von Neumann embeddings: Corrections and reproducible counterexamples"]
28 October 2026
[under "Abstract"] [block of 1505 characters not shown; it begins "We examine version 2 of arXiv:2609.28999, which reconstructs conservative nonlin…"]
[under "1. Introduction and scope"]
The present note concerns statements that can be checked independently of a large-scale quantum implementation. Its main contributions are: (i) an exact initial-separation obstruction to the geometric criterion printed in source Eqs. (30)–(31); (ii) an exact characterization and nonidentifiability example for the proposed reference-phase readout; and (iii) reproducible corrections to sampling prefactors, a benchmark calibration, and regularity assumptions. Each correction is local to the statement identified. Standard ingredients such as Taylor’s theorem, characteristic functions, and quantum amplitude estimation are credited rather than presented as new general theory.
[under "Proof"]
Thus the approximately $0.1$ condition printed in source Eq. (31) cannot hold under the directional-map interpretation given in its geometric discussion. If the intended map were instead the complete flow, the time-zero contradiction in (3) would still remain: the normalized raw separation tends to $1$, rather than $0$, as $h\to0$.
…and 61 more blocks not shown.