slug: garcia-volcic-2025-nc-hunter-kernel-rigidity bibkey: garciavolcic2025hunter doi: 10.1090/proc/17480 url: https://arxiv.org/abs/2503.12376v2 triage: theorem motivation_gids:

• D5/S3/Analytic/Hunter/NCHunterKernelRigidity.result

Garcia–Volčič Conjecture 4.5

Problem

S. R. Garcia and J. Volčič, “A noncommutative generalization of Hunter’s positivity theorem”, arXiv:2503.12376v2, Conjecture 4.5, states:

Let $n,d\ge 2$. For all tuples of hermitian operators $X_1,\dots ,X_n$ on a Hilbert space, $\ker (H_{2d}(X_1,\dots ,X_n)-{\mu }_{n,d}(X_1^{2d}+\cdots +X_n^{2d}))=\ker X_1\cap \cdots \cap \ker X_n$.

The settled assertion is exactly the bounded complex Hilbert-space statement preregistered in #13735. Here $H_k(X)$ is the ordered word sum, with each word $w$ weighted by ${\prod }_i{m}_i(w)!/k!$. This is the reciprocal cardinality of the word’s abelianization fibre. The constant ${\mu }_{n,d}$ retains the source’s $n=1$, odd-degree and even-degree branches.

Motivation

D5/S3/Analytic/Hunter/NCHunterKernelRigidity.result proves the kernel identity for all $n,d\ge 2$, every complete complex inner-product space, and every bounded complex-linear self-adjoint tuple. The conclusion is equality of kernel submodules, without an additional positivity or certificate hypothesis. NCHunterPositivity.sharp_positivity supplies the source’s operator lower bound for $n>0,d>0$.

Gap

The source proves the case $n=d=2$ in Example 4.4 and leaves the general kernel assertion as Conjecture 4.5. The Tier-1 preregistration records the source statement, quantifiers, MathDB entry, and citing-work search. Brazitikos–Pandis, arXiv:2512.12254, addresses scalar Hunter positivity; arXiv:2606.12866 cites the positivity theorem. These checked sources supply no settlement of the kernel assertion. This is a bounded literature search, not an exhaustive claim about unpublished work.

Route

The urn recursion gives an inverse-column formula and representers satisfying $GR=E$. Together with the pure-word block bound, this yields $G-\mu M⪰0$. The residual’s quadratic form is the factorial Gram form of length-$d$ words applied to a vector.

A vector in the residual kernel has zero form, so every mixed-word row vanishes. A positive definite shifted factorial kernel forces the grouped word coefficients to vanish. Even and odd degrees use separate contractions. Self-adjoint operators and their positive powers have the same kernel; this converts the word relations into the common operator kernel. Every positive-length word vanishes on that common kernel, giving the reverse inclusion.

Falsifier

A falsifier is a bounded self-adjoint tuple on a complex Hilbert space, with $n,d\ge 2$, and a vector belonging to exactly one side of the displayed kernel equality. GVHunter.result excludes this within the stated carrier. Unbounded operators and their domains do not belong to this assertion.

Evidence

The Lean modules are D5/S3/Analytic/Hunter/NCHunterPositivity.lean and D5/S3/Analytic/Hunter/NCHunterKernelRigidity.lean; their mirrors are under Blueprint/D5/S3/Analytic/Hunter/. The settling Scribe node records an OpenProblemResolutionClaim with resolution Proved for this dossier.

The positivity module has admission_basis: escape-witness, with urn_closed_form on the live path through inverse_word_sum, representer_certificate, sharp_gram_posSemidef and sharp_positivity. The settling module has admission_basis: open-problem-resolution (#13735; Proved). Consumed bind-only helpers organize the proof and supply no independent admission basis.

The axiom closure of every public declaration is contained in $\{\mathrm{propext},Classical.choice,Quot.sound\}$. Information-escape registration is paused under CLAUDE.md §3.9.

Triage

What the settlement shows

• Proved: the preregistered bounded complex Hilbert-space kernel equality, by GVHunter.result. The decisive mechanism is the positive residual Gram form, mixed-row vanishing and strictly positive shifted factorial kernel. The argument has no finite-dimensional restriction.
• Proved, direct consequence: equality in the operator lower bound occurs precisely at the zero tuple. If the residual operator is zero, its kernel is the whole space; GVHunter.result then makes each $\ker X_i$ the whole space, hence each $X_i=0$. The reverse implication follows by evaluating the positive-degree word sum at the zero tuple. This consequence is not an additional public declaration in either module.
• Open, outside the formal conclusion: the source’s finite-dimensional, tuple-dependent $\epsilon >0$ improvement $H_{2d}(X)⪰({\mu }_{n,d}+\epsilon ){\sum }_i{X}_i^{2d}$. The kernel identity supplies the common nullspace needed by the spectral argument, but a finite-dimensional spectral comparison is not formalized here. No uniform improvement over all tuples is asserted.
• Open, outside the statement: unbounded self-adjoint operators. Products, sums and kernels require common-domain hypotheses absent from the bounded operator encoding; no unbounded extension is asserted.
• Open, untouched: Conjecture 4.6, complete positivity of $G_{n,d}$, meaning a factorization $S^{\ast }S$ with entrywise nonnegative $S$. Positive semidefiniteness alone does not supply this factorization. The source’s proposed sum-of-Hermitian-squares representations with nonnegative coefficients therefore remain outside this settlement.
• Open, outside the formal conclusion: optimality of ${\mu }_{n,d}$. Theorem 1.1(ii) attributes sharpness to the source; these modules prove positivity at that constant and the kernel equality, not optimality.
• Open as an originality claim; literature-attested identity: the scalar shifted factorial Gram identity is an application of Chu–Vandermonde, NIST DLMF equation 15.4.24, https://dlmf.nist.gov/15.4.E24 . Expanding $F(-a,-b;g+1;1)=(g+1+b{)}_a/(g+1{)}_a$ and multiplying by $(a+g)!(b+g)!/g!$ gives the scalar identity; products over letters give the finite Gram representation. Neither that scalar identity nor the product construction is claimed original. The new formal proof uses this representation to settle the preregistered kernel assertion.
• Proved, scope of dependence: the bounded version of the source’s first consequence follows from the settled kernel identity. The finite-dimensional $\epsilon$ consequence retains its unformalized spectral step. The source’s existing positivity theorem is formalized, while Conjecture 4.6 and its nonnegative-coefficient consequences are not settled.

ASSUMED-UNVERIFIED

The literature inventory is limited to the source, the preregistration’s MathDB and citing-work checks, and the reviewed search scope. Absence of unpublished settlements is not certified. Failed upstream-only probes show failure of the tested direct routes only; they do not establish impossibility of every alternative upstream route.