Abstract

We show that if {φi}iΓ\lbrace \varphi_i\rbrace_{i\in Γ} and {ψj}jΛ\lbrace ψ_j\rbrace_{j\inΛ} are self-affine iterated function systems on the plane that satisfy strong separation, domination and irreducibility, then for any associated self-affine measures μμ and νν, the inequality dimH(μν)<min{2,dimHμ+dimHν}\dim_{\rm H}(μ*ν) < \min \lbrace 2, \dim_{\rm H} μ+ \dim_{\rm H} ν\rbrace implies that there is algebraic resonance between the eigenvalues of the linear parts of φi\varphi_i and ψjψ_j. This extends to planar non-conformal setting the existing analogous results for self-conformal measures on the line.

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Audited against arXiv v5

Not a correctness certificate. A “Correct” result may include yellow typos or minor formal corrections that do not affect substantive soundness. It means this audit found no unresolved substantive error under the stated criteria; it does not replace expert scrutiny or formal verification.

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Detailed mathematical audit

Generated August 18, 2026
01Statements3 reported findingsCorrect

The resonance theorem, the general lower bound for convolution dimension, and the set-valued corollary are correct. The proof's varying-scale quantifier error does not disprove Theorem 1.2: its actual application admits a verified countable-restriction repair.

Theorem 1.1Correct

Resonance between dominated planar self-affine measures

Pages 3-4 and 30-31 · Theorem 1.1 and its proof · arXiv:2302.05240v5

Under irreducibility, domination, strong separation, full support, and dimμdimν\dim\mu\geq\dim\nu, the proof correctly reduces any dimension drop to dimμ>1>dimν\dim\mu>1>\dim\nu and then combines the fiber-structure estimate with the product-flow entropy estimate. If the logarithmic eigenvalue set is not arithmetic, a pair has irrational ratio; Proposition 6.1 supplies a common sampling time for which the relevant product flow is ergodic, and Claims 4.3-4.4 inserted into (4.4) give dim(μν)min{2,dimμ+dimν}\dim(\mu*\nu)\geq\min\{2,\dim\mu+\dim\nu\}, contradicting the assumed drop.

Full paper, version 5
Theorem 1.2Correct

Lower bound for convolution dimension

Page 4, pages 23-27, and pages 49-51 · Theorems 1.2 and 3.2; Claim 4.2 · arXiv:2302.05240v5

Claim 4.2 gives the required entropy lower bound on the increasing sets Xm={(i,j):d(θ(i),θ(j))1/m}X_m=\{(\mathbf i,\mathbf j):d(\theta(\mathbf i),\theta(\mathbf j))\geq1/m\}, whose union has full measure. For each fixed mm, a single sufficiently large βm\beta_m works almost everywhere on XmX_m. Apply the fixed-β\beta tree argument to the normalized restriction on XmX_m; differentiation makes its cylinder conditionals asymptotic to the unrestricted ones. If a Borel set has positive μν\mu*\nu-measure, its preimage under addition meets some XmX_m in positive measure, so the restricted lower bound forces that set to have dimension at least min{1,dimμ}+min{1,dimν}ε\min\{1,\dim\mu\}+\min\{1,\dim\nu\}-\varepsilon. Letting ε0\varepsilon\downarrow0 proves the theorem. This is a complete repair of the defective general varying-β\beta paragraph identified in Part 2.

Hochman-Shmerkin, local entropy averages
Corollary 1.3Correct

Resonance statement for self-affine attractors

Page 5 · Corollary 1.3 and its proof · arXiv:2302.05240v5

The cited variational approximation produces fully supported block-system measures with dimensions arbitrarily close to those of the two attractors. The strict dimension gap persists after this approximation, Theorem 1.1 gives the arithmetic eigenvalue conclusion, and Theorem 1.2 excludes the remaining boundary case dimY=1\dim Y=1.

Full paper, version 5
02Proofs4 reported findingsContains incorrect or incomplete proofs

The dependent-β\beta extension of the local-entropy theorem invokes Egorov's theorem to interchange an existential scale quantifier with a uniform tail quantifier, which is invalid. The actual use in Theorem 1.2 has a verified repair by the countable angle-separation decomposition. Three additional notation and scale-growth defects are harmless typos.

Proof of Theorem 3.2Incorrect as written

Egorov's theorem does not make a point-dependent scale uniform

Page 27 · dependent-β\beta paragraph after Equation (3.3) · arXiv:2302.05240v5

The hypothesis says that for almost every (i,j)(\mathbf i,\mathbf j) there exists some β=β(i,j,ε)N0\beta=\beta(\mathbf i,\mathbf j,\varepsilon)\geq N_0 for which the entropy condition holds. The proof then claims that Egorov's theorem gives a large set EE and N1N_1 on which the condition holds for every βN1\beta\geq N_1. Egorov only makes convergence uniform for an already fixed sequence of functions; it cannot replace (i,j)β\forall(\mathbf i,\mathbf j)\,\exists\beta by N1(i,j)βN1\exists N_1\,\forall(\mathbf i,\mathbf j)\,\forall\beta\geq N_1. Thus the general extension is not proved. Downstream dependency: Claim 4.2 invokes precisely the point-dependent version in the proof of Theorem 1.2. Verified repair for that use: Claim 4.2 already partitions the full-measure set as mXm\bigcup_m X_m, and for each fixed mm a common βm\beta_m works on XmX_m; apply the fixed-scale restriction argument separately to each XmX_m. Every positive-measure preimage meets some XmX_m positively, so the resulting countable family of restricted estimates proves the lower Hausdorff-dimension bound for the full convolution. This repair does not validate the broader variable-β\beta statement without additional hypotheses.

Full paper, version 5
Notation 3.1Typo

The magnification of μ\mu is defined using the wrong measure

Page 23 · second display in Notation 3.1 · arXiv:2302.05240v5

Printed: μiik:=SkβTΠ(i)φiikν\mu_{\mathbf i|i_k}:=S_{k\beta}^*T_{\Pi(\mathbf i)}\varphi_{\mathbf i|i_k}\nu. Correction: replace the final ν\nu by μ\mu. The symbol is used thereafter as the magnification of μ\mu, and the corrected formula is written explicitly at the start of the proof of Claim 4.2. No argument changes.

Full paper, version 5
Proof of Theorem 3.2Typo

The coding-length increments have order β\beta, not logβ\log\beta

Page 25 · paragraph defining the finite alphabets AA and BB · arXiv:2302.05240v5

The paper says that the block-length increments are bounded by constant multiples of logβ\log\beta. The dyadic increment is (k+1)βkβ\lfloor(k+1)\beta\rfloor-\lfloor k\beta\rfloor, hence is of order β\beta; the stopping-time increment for a fixed contracting IFS has the same order. The unique correction is to replace logβ\log\beta by β\beta. Only finiteness for each fixed β\beta is used, so the proof is unaffected.

Full paper, version 5
Proof of Claim 4.3Typo

The definition of FF' omits the map FF

Page 51 · first paragraph of the proof of Claim 4.3 · arXiv:2302.05240v5

Printed: F:ZΦP(R2)F':Z'_\Phi\to\mathcal P(\mathbb R^2) is defined by F(i,θ,t)=(i,θ,1,t)F'(\mathbf i,\theta,t)=(\mathbf i,\theta,1,t), whose right-hand side is a point of ZΦZ_\Phi, not a probability measure. Correction: F(i,θ,t)=F(i,θ,1,t)F'(\mathbf i,\theta,t)=F(\mathbf i,\theta,1,t). All subsequent expressions treat FF' as this measure-valued composition, so the correction is unique and harmless.

Full paper, version 5
03Novelty0 reported findingsNo non-novelty findings

No non-novelty findings.

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Paper
arXiv:2302.05240v5
Authors listed
Aleksi Pyörälä
Audit date
August 18, 2026
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