§ 13.19updated 2026-06-08

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OP-48 point (c): a state-/collar-free composition surrogate on Type III₁?

Status: SETTLED as a conditional no-go for OP-48(c) (medium-high confidence); headline verdict encodes-not-generates STANDS and is tightened, not flipped. Last updated: 2026-06-08 Iteration: 5


Goal

Resolve OP-48 point (c): exhibit, or prove impossible, a state-independent, collar-free composition surrogate that singles out quantum theory from split-style composition axioms on a Type III1_1 factor — converting the partial A+BA+B merge into a full merge, or establishing a clean no-go.

Iteration 4 left (c) OPEN: the split property gives only a state-/collar-dependent factorization (canonical only relative to the vacuum modular conjugation JJ, failing at zero collar). The closing question this note attacks: is there a canonical, choice-free composition surrogate — Haagerup standard form / natural cone, Connes spatial theory, Connes fusion, the funnel property, or an operational commuting-pair axiomatization — and does it single out QM, or does any QM-selecting surrogate necessarily reintroduce a state/collar dependence?

See ../open-problems.md (OP-48), the predecessor note 2026-05-xx-iter4-op48-split-composition.md for the iter-4 framing, and the domain page ../domains/operator-algebras.md.


Setup (real math)

Two background facts fix the arena.

(i) The local algebra is hyperfinite Type III1_1. In relativistic QFT a single local algebra M=A(O)\mathcal{M}=\mathcal{A}(O) is the hyperfinite Type III1_1 factor (Connes–Haag–Araki) ESTABLISHED. Consequently there is no trace, no minimal projection, no density matrix, and no factorization HHMHM\mathcal{H}\neq\mathcal{H}_{\mathcal{M}}\otimes\mathcal{H}_{\mathcal{M}'}. So the GPT local-tomography axiom dimVAB=dimVAdimVB\dim V_{AB}=\dim V_A\cdot\dim V_B is not statable verbatim on M\mathcal{M} ESTABLISHED.

(ii) Iter-4 settled the split route. The split property restores an exact HH1H2\mathcal{H}\cong\mathcal{H}_1\otimes\mathcal{H}_2 for a nested inclusion O1O2O_1\Subset O_2, but only with a nonzero collar and only canonically relative to a cyclic–separating Ω\Omega via the intermediate Type I factor associated with NJNJN\vee JNJ. Hence it is both state-dependent (the canonical intermediate factor is fixed by Ω\Omega's modular JJ; Doplicher–Longo 1984 give infinitely many intermediate factors otherwise) and collar-dependent (Fewster: the split inclusion fails for touching/adjacent regions) ESTABLISHED.

Point (c) asks for a surrogate avoiding both dependencies. The structural candidates, with their honest state/collar status:

1. Haagerup standard form (M,H,J,P)(\mathcal{M},\mathcal{H},J,\mathfrak{P}). Every von Neumann algebra has a canonical self-dual natural cone P\mathfrak{P} and conjugation JJ with JMJ=MJ\mathcal{M}J=\mathcal{M}'; the quadruple is unique up to unitary equivalence (Haagerup 1975; Araki, and Connes for the σ\sigma-finite case) ESTABLISHED, web-confirmed. This is genuinely canonical and state-independent: the datum is the cone P\mathfrak{P}, not a preferred vector. But it furnishes only the commutant pairing (M,M)(\mathcal{M},\mathcal{M}') — not a tensor factorization.

2. Connes fusion / Sauvageot relative tensor product. The Connes spatial derivative dψ/dφd\psi/d\varphi and Sauvageot's relative tensor product HNK\mathcal{H}\otimes_N\mathcal{K} of bimodules (correspondences) over a common NN give a composition operation that "adjusts the naive algebraic tensor product," defined intrinsically from the bimodule structure, requiring no Hilbert-space tensor factorization and no collar (Connes; Sauvageot 1983; Thom) ESTABLISHED, web-confirmed. It is independent of the chosen faithful normal weight up to unique isomorphism, and is defined for any type including III1_1.

3. The van Luijk operational program. The van Luijk–Stottmeister–Werner–Wilming work (arXiv:2401.07299; PRL 133, 261602 (2024) = arXiv:2401.07292; review arXiv:2510.07563, Dec 2025) derives the von Neumann–algebraic description of a subsystem from operational axioms (Limits, Ancillas, Dilations, Reversibility, Postselection). Its core theorem: the implementable operations are exactly the M\mathcal{M}-inner ones for a unique von Neumann algebra M\mathcal{M}, and a bipartite system is a commuting pair (MA,MB)(\mathcal{M}_A,\mathcal{M}_B) on a shared H\mathcal{H} — state-independent, collar-free, no tensor product assumed ESTABLISHED, web-confirmed.

Referee correction carried (op48c:claim). The axiom-enumeration label "A1–A5" and the descriptor "Theorem A" are the wiki's paraphrase of arXiv:2510.07563, not verbatim named results in the source, and are used here only as shorthand. Likewise, Haag duality is a property a net may satisfy or violate (it can fail under spontaneous symmetry breaking, for disconnected regions, etc.); what is genuinely type-agnostic is the commuting-pair / standard-form / Connes-fusion structure, not "Haag duality for all types." [FLAGGED]


The attempt

Each candidate was carried to its honest limit, then assembled into the strongest QM-selection argument.

Step 1 — A state-independent, collar-free composition surrogate DOES exist. Combine:

  • (a) the Haagerup standard form, which canonically (state-independently) furnishes the commuting pair (M,M)(\mathcal{M},\mathcal{M}') via JMJ=MJ\mathcal{M}J=\mathcal{M}' and the self-dual cone P\mathfrak{P};
  • (b) the van Luijk operational axiomatization, which derives precisely this commuting-pair structure from operations; and
  • (c) Connes fusion N\otimes_N as the intrinsic, weight-independent composition law over a shared algebra.

Each ingredient is web-confirmed ESTABLISHED. Therefore the iter-4 framing — "any canonical composition re-imports a reference state (BREAK 1) and a collar (BREAK 2)" — is FALSE for this surrogate: the commuting-pair / standard-form / Connes-fusion package is genuinely collar-free (no O1O2O_1\Subset O_2; defined for touching/coincident algebras) and reference-state-free (canonical from the cone, not a vector). This is a real advance on (c): the surrogate exists and is exhibited.

Step 2 — Does it single out QM? Here the attempt breaks. The surrogate is provably type-agnostic: the commuting-pair structure and standard form hold for every von Neumann algebra type (I, II, III) verbatim. They characterize "von-Neumann / quantum-logical composition in general," not Type-I textbook QM. In particular they contain no local-tomography clause that would force the complex field and the tensor product; the commuting-pair / Haag-duality datum is strictly weaker than dimVAB=dimVAdimVB\dim V_{AB}=\dim V_A\dim V_B.

Step 3 — The operational invariant. The same framework supplies a state-independent operational invariant that separates types: the worst-case embezzlement error κmax(MA,MB)\kappa_{\max}(\mathcal{M}_A,\mathcal{M}_B) (van Luijk et al., arXiv:2401.07299, Thm E; companion arXiv:2401.07292). Its values ESTABLISHED, web-confirmed:

κmax=2(semifinite: Type I and all Type II — no embezzling states),\kappa_{\max}=2 \quad\text{(semifinite: Type I \emph{and all} Type II — no embezzling states)}, κmax=2(1λ)1+λ(Type IIIλ),κmax=0(Type III1 — every normal state embezzling: universal embezzler).\kappa_{\max}=\frac{2\,(1-\sqrt{\lambda})}{1+\sqrt{\lambda}} \quad\text{(Type III}_\lambda), \qquad \kappa_{\max}=0 \quad\text{(Type III}_1\text{ — every normal state embezzling: universal embezzler).}

Note the convention: κ\kappa is a failure measure — κ=0\kappa=0 means embezzlement succeeds universally, κ=2\kappa=2 means it maximally fails.

So the collar-free commuting-pair composition, applied to the physically relevant Type III1_1 local algebra, has a non-classical operational signature — universal entanglement embezzlement — that finite-dimensional QM (Type I, κmax=2\kappa_{\max}=2) provably does not share.

Referee correction carried (op48c:claim, op48c:NI1) — load-bearing. κmax=2\kappa_{\max}=2 holds for Type I AND all of Type II (semifinite), not Type I alone. So κmax=2\kappa_{\max}=2 does not identify Type I, and the value of the embezzlement invariant alone does not force a tensor factorization: the wiki's own CLPW construction yields a Type II1_1 factor, which has κmax=2\kappa_{\max}=2 yet has no local-tomography subsystem factorization (it has a trace, not subsystem tensor factors). The Type-I interposition in Step 4 below therefore comes from the split property (an independent structural input), not from "κmax=2\kappa_{\max}=2" per se. [FLAGGED — corrects the iter-5 first-pass framing.]

Step 4 — The assembled selection argument (and where it must be hedged). The remaining inference is: to force QM-like composition (a genuine tensor factorization with bounded embezzlement) you must leave Type III1_1 — i.e. interpose a Type I factor, which on a net is the split construction with its collar and reference-state canonicity tax. As corrected, this requires the split property's atoms + factorization, not merely κmax=2\kappa_{\max}=2; the dichotomy is real but the bridge "QM-type composition \Leftrightarrow κmax=2\kappa_{\max}=2" is not a cited theorem and is carried as INFERENCE.


Where it breaks / what moved (didItMove = advanced)

The break is at Step 2, and iter-5 makes it a structured obstruction rather than the bare iter-4 OPEN. The exhibited state-independent, collar-free surrogate (Haagerup cone + commuting-pair operational axiomatization + Connes fusion) singles out "von Neumann / quantum-logical composition," but not quantum theory in the GPT sense, for two web-verified reasons:

  1. Type-agnosticism. The commuting-pair structure and standard form hold for all types, so they cannot select the complex field, the tensor product, or Type I. There is no collar-free analogue of local tomography in the package.

  2. Wrong-direction operational signature. On the physical Type III1_1 factor the collar-free composition is a universal embezzler (κmax=0\kappa_{\max}=0): every normal state lets one extract arbitrary entanglement by local operations with arbitrarily small disturbance. Finite-dim QM composition (Type I) is the antipodal κmax=2\kappa_{\max}=2. So the collar-free surrogate, on III1_1, is operationally distinguishable from — indeed opposite to — finite-dim QM.

What moved: OPEN \rightarrow a structured conditional no-go with a web-verified operational invariant (κmax\kappa_{\max}) doing the separating work. didItMove = advanced. This did not flip the headline verdict: no emergent Lorentzian geometry from non-symmetric data was derived, and the QM-selecting axiom is shown to coincide with the geometry-/state-importing split input, reinforcing rather than overturning encodes-not-generates (see ../README.md and ../verdicts.md).


Furthest defensible claim

INFERENCE, high — obstruction-sharpening, NOT a clean proved theorem On a single hyperfinite Type III1_1 factor there is a strong tension — plausibly a conditional no-go modulo one named bridge — between the two desiderata of OP-48(c):

  • A genuinely state-independent, collar-free composition surrogate exists: the commuting pair (M,M)(\mathcal{M},\mathcal{M}') from the Haagerup standard form, with operations characterized as M\mathcal{M}-inner via the van Luijk operational axiomatization, and Connes fusion as a weight-independent associative composition law. But it is type-agnostic and, on III1_1, carries the universal-embezzlement signature κmax=0\kappa_{\max}=0 — the operational antipode of finite-dim QM (Type I, κmax=2\kappa_{\max}=2) — so it does not single out quantum theory.
  • Conversely, recovering finite-dim-QM-like composition (atoms, exact tensor factorization, local tomography, no embezzling states) on a III1_1 region requires interposing a Type I factor via the split property, which re-imports a nonzero collar (Fewster: fails for adjacent regions) and a reference-state canonicity tax (canonical intermediate factor fixed only by Ω\Omega's modular JJ; Doplicher–Longo 1984; Hollands–Longo 2020).

Hence "collar-free + state-independent" and "singles out QM" are in irreducible tension on one III1_1 factor.

Two referee-mandated hedges baked into the statement above:

  • κmax=2\kappa_{\max}=2 does not force Type I — Type II and III0_0 share it. The Type-I interposition is supplied by the split property (atoms + factorization), not by the embezzlement value. [FLAGGED]
  • "κmax\kappa_{\max} signature \Leftrightarrow local tomography / tensor factorization / QM-ness" is an unproven bridge — the embezzlement literature (arXiv:2401.07299/2401.07292) never connects κmax\kappa_{\max} to local tomography, the tensor product, the split property, or GPT composition. It is carried as INFERENCE, not theorem-grade. [FLAGGED]

If it fails / weaker statement

If the no-go (horn C) is wrong, the failure point is the implicit assumption that QM-selecting composition requires bounded embezzlement / a Type I factorization. The loophole: a complex-field/tensor-selecting axiom might be expressible directly at the III1_1 commuting-pair level (e.g. a modular-compatible reversibility clause or a Connes-fusion-based duotensor condition) without demanding κmax=2\kappa_{\max}=2 — so QM could in principle be singled out among type-agnostic von Neumann composition theories by a clause orthogonal to the embezzlement invariant. Note also that κmax=0\kappa_{\max}=0 on III1_1 means III1_1 already supports a rich bipartite operational task (embezzlement) without any Type I split — evidence that III1_1 has its own bipartite structure, which itself cuts against "QM-like composition only via splitting."

To probe the loophole one would check whether the Pati no-signalling inner-product rigidity (arXiv:2601.13012) can be re-expressed intrinsically on a III1_1 commuting pair without presupposing the tensor structure it currently assumes. Iter-4 and iter-5 both find it presupposes HAHB\mathcal{H}_A\otimes\mathcal{H}_B and local unitaries (verified verbatim), so as published it fixes the inner product on a given Hilbert space, not the composition rule, and cannot be stated on a single III1_1 factor — it does not close the loophole. Similarly Torres Alegre (arXiv:2602.09056) fixes only the Born form via GNS, not composition.

Weakest defensible fallback (if even existence, horn A, is contested): the Haagerup standard form alone is uncontestably state-independent and collar-free, so at minimum the bare commutant pairing (M,M)(\mathcal{M},\mathcal{M}') is a canonical, reference-free "composition arena." The no-go would then bite only on the "singles out QM" clause — which is the published, web-verified part.


Proposed registry items (with referee verdicts)

OP-GPT-TYPE3 — gap-refinement [bundle: MIXED]

OP-48 point (c) resolves as a conditional no-go (upgrading the iter-4 OPEN), entirely within operator-algebra / QI structure and with no geometric (Lorentzian) content. (A) ESTABLISHED A state-independent, collar-free composition surrogate exists on a III1_1 factor: the commuting pair (M,M)(\mathcal{M},\mathcal{M}') from the standard form, with operations characterized as M\mathcal{M}-inner via the van Luijk operational axiomatization (arXiv:2510.07563), and Connes fusion / the Sauvageot–Connes relative tensor product as a weight-independent composition law. (B) ESTABLISHED It does NOT single out QM: type-agnostic; no local-tomography clause (the commuting-pair datum is strictly weaker than dimVAB=dimVAdimVB\dim V_{AB}=\dim V_A\dim V_B, and on factors corresponds only to subfactor irreducibility); on III1_1 carries κmax=0\kappa_{\max}=0 (arXiv:2401.07299), opposite to finite-dim/Type I QM (κmax=2\kappa_{\max}=2). (C) INFERENCE, high Recovering QM-type composition (tensor factorization / local tomography) requires interposing a Type I factor via the split construction (Doplicher–Longo 1984), re-importing product structure and a canonical reference state; hence "collar-free + state-independent" and "singles out QM" cannot both hold on one III1_1 factor.

Referee verdict (op48c:NI0 — keep, severity minor, isSound = true). Accepted with cosmetic flags: the "A1–A5"/"Haagerup standard form"/"canonicity tax" labels are the wiki's faithful paraphrase, not verbatim source enumerations; the Thom attribution for Connes fusion is loose (rigorously Sauvageot 1983 / Connes). Substance verified: arXiv:2510.07563 and arXiv:2401.07299 are real; the κmax\kappa_{\max} values are correct; the split property (Doplicher–Longo 1984) is correctly characterized; "Haag duality strictly weaker than local tomography" is correct, with recent work (arXiv:2509.12911, PRL) confirming Haag duality \Rightarrow local tomography only for factors. No fabricated citations, theorems, or numbers. Makes no Lorentzian claim and does not purport to flip the headline. Bundle tag MIXED stands.

HYP-EMBEZZLE-SELECT — new-hypothesis [tag downgraded to SPECULATIVE]

The state-independent algebraic witness κmax(M)\kappa_{\max}(\mathcal{M}) vanishes (=0=0) exactly on Type III factors (universal embezzlement) and is maximal (=2=2) on all semifinite factors. Restricted to distinguishing Type I from Type III1_1 (NOT Type II, which also gives 22), it offers a state-independent re-encoding of the iter-4 obstruction: recovering textbook-QM (Type I) composition / local tomography on a III1_1 net forces leaving the III1_1 class, implemented on a net by the split (intermediate Type I factor) and therefore collar- and reference-state-dependent. This sharpens, and does not flip, encodes-not-generates, by supplying a state-independent invariant where iter-4 used a state-dependent split argument.

Referee verdict (op48c:NI1 — keep, severity MAJOR, isSound = false on the original strong form). The original phrasing — "κmax\kappa_{\max} precisely distinguishes Type I from III1_1," "operationally equivalent to demanding a Type I intermediate factor," "two faces of the same requirement," tagged INFERENCE, high — was rejected for: (1) false type-discrimination (κmax=2\kappa_{\max}=2 for Type I and II; only III is 00); the Type II1_1 counterexample breaks "κmax=2\kappa_{\max}=2\Rightarrow factorization"; (2) an unsupported equivalence chain (the source never connects embezzlement to local tomography, tensor factorization, the split property, or GPT composition); (3) a single-factor vs inclusion category error (κmax\kappa_{\max} is a single-factor invariant; the split concerns a nested pair); (4) internal tension — κmax=0\kappa_{\max}=0 shows III1_1 has its own bipartite operational structure without any split; (5) a semantic gloss (κ=2\kappa=2 is maximal embezzlement failure, not "QM-good high value"). Recommended tag: SPECULATIVE. The refined, defensible residue is the INFERENCE, low–medium statement above: κmax\kappa_{\max} is a state-independent witness separating semifinite from Type III, and restricted to I-vs-III1_1 it re-derives the iter-4 obstruction with a state-independent invariant in place of a state-dependent split — a modest strengthening, not a new equivalence. Recorded accordingly.


Verdict

SETTLED as a clean conditional no-go for OP-48(c) (medium-high confidence); the headline did NOT flip — encodes-not-generates STANDS and is tightened.

  • (i) Existence. A state-independent, collar-free composition surrogate genuinely exists — the commuting pair (M,M)(\mathcal{M},\mathcal{M}') from the Haagerup standard form, operationally axiomatized by van Luijk et al., with Connes fusion as its weight-independent composition law ESTABLISHED, web-confirmed. This refutes the iter-3/4 presumption that any canonical composition must cost a collar and a reference state.
  • (ii) No selection. But it does not single out QM: type-agnostic, no local-tomography clause, and on the physical Type III1_1 factor a universal embezzler (κmax=0\kappa_{\max}=0), the operational opposite of finite-dim QM (Type I, κmax=2\kappa_{\max}=2) ESTABLISHED, web-confirmed.
  • (iii) The tax returns. Any QM-selecting composition (atoms / tensor factorization / local tomography) on a III1_1 region forces a Type I intermediate factor via the split property, re-importing collar- and state-dependence INFERENCE, high. So "collar-free + state-independent" and "singles out QM" are incompatible on one III1_1 factor.

The 2026 rigidity results do not rescue selection: Pati (arXiv:2601.13012) fixes the inner product but presupposes the bipartite tensor product (verified verbatim) and is not statable on a single III1_1 factor; Torres Alegre (arXiv:2602.09056) fixes only the Born form, not composition.

didItMove = advanced (OPEN \to structured conditional no-go with a web-verified operational invariant doing the work). Not flips-headline-verdict: no emergent Lorentzian geometry from non-symmetric data was derived, and the QM-selecting axiom is shown to coincide with the geometry/state-importing input. Confidence medium-high: horns (A),(B) are ESTABLISHED and triple-web-verified; horn (C)'s "must interpose Type I" step is INFERENCE — strongly supported by the type classification but not a cited theorem in the exact phrasing, and the embezzlement\leftrightarrowcomposition bridge is explicitly conjectural.


Open subquestions

  1. OPEN — decides HYP-EMBEZZLE-SELECT Is horn (C) a theorem: must every composition surrogate with QM-type behavior (local tomography / genuine tensor factorization) on a III1_1 net factor through a Type I intermediate factor (the split)? Or is there a complex-field/tensor-selecting axiom expressible directly at the III1_1 commuting-pair level, orthogonal to the embezzlement invariant?
  2. OPEN Can the Pati no-signalling inner-product rigidity (arXiv:2601.13012) be reformulated intrinsically on a III1_1 commuting pair (M,M)(\mathcal{M},\mathcal{M}') without presupposing HAHB\mathcal{H}_A\otimes\mathcal{H}_B — e.g. via the natural cone / a Connes-fusion duotensor — turning an inner-product-fixing result into a composition-fixing one? As published it cannot.
  3. OPEN Does the van Luijk axiom set admit a strengthening (a tomographic / reversibility / complex-structure clause) that singles out Type I among all von Neumann types without a collar — or is type-agnosticism provably irreducible for any operational axiomatization on a shared Hilbert space?
  4. OPEN Connes fusion is weight-independent up to unique isomorphism: is the natural transformation implementing that isomorphism itself free of any modular/geometric input, or does canonicity of the fusion associator covertly re-introduce a preferred weight (a higher-categorical analogue of the iter-4 canonicity tax)?
  5. OPEN — verification Peer-review status of the 2026 preprints (Pati arXiv:2601.13012; Torres Alegre arXiv:2602.09056) remains unconfirmed; the van Luijk PRL (133, 261602, 2024) and the embezzlement-classification results are published/peer-reviewed and are the load-bearing citations for the no-go.

See also

Key results cited

  • van Luijk, Stottmeister, Werner, Wilming, Embezzlement of entanglement, quantum fields, and the classification of von Neumann algebras, arXiv:2401.07299 (2024) — κmax\kappa_{\max} operational invariant; =2=2 for semifinite (Type I and II), 2(1λ)1+λ\frac{2(1-\sqrt\lambda)}{1+\sqrt\lambda} for IIIλ_\lambda, =0=0 for III1_1. ESTABLISHED, web-confirmed
  • van Luijk, Stottmeister, Werner, Wilming, Relativistic Quantum Fields Are Universal Entanglement Embezzlers, arXiv:2401.07292; Phys. Rev. Lett. 133, 261602 (2024) — QFT local (III1_1) algebras are universal embezzlers, κmax=0\kappa_{\max}=0. ESTABLISHED, web-confirmed
  • van Luijk, Entanglement in von Neumann Algebraic Quantum Information Theory, arXiv:2510.07563 (2025) — operational derivation: implementable operations =M=\mathcal{M}-inner ones; bipartite system == commuting pair; type classification in 1–1 correspondence with operational embezzlement properties. ESTABLISHED, web-confirmed
  • Connes (J. Funct. Anal. 35 (1980) 153); Sauvageot (1983); Thom (arXiv:math/0601045, TAC 25 (2011) 38) — Connes fusion / relative tensor product: intrinsic, collar-free, weight-independent up to unique isomorphism. ESTABLISHED, web-confirmed
  • Haagerup, The standard form of von Neumann algebras, Math. Scand. 37 (1975) 271; Araki; Connes (σ\sigma-finite case) — canonical (M,H,J,P)(\mathcal{M},\mathcal{H},J,\mathfrak{P}), JMJ=MJ\mathcal{M}J=\mathcal{M}', unique up to unitary equivalence; state-independent. ESTABLISHED, web-confirmed
  • Doplicher–Longo (1984); Hollands–Longo (2020) — split property and intermediate Type I factor; infinitely many absent a reference Ω\Omega. ESTABLISHED
  • Pati, No-Signalling Fixes the Hilbert-Space Inner Product, arXiv:2601.13012 (2026) — fixes inner product but presupposes HAHB\mathcal{H}_A\otimes\mathcal{H}_B and local unitaries (verified verbatim); fixes the inner product, not the composition rule. Does not close (c). ESTABLISHED claim; peer review unconfirmed
  • Torres Alegre, Causal Rigidity of Born-Type Probability Rules in Infinite-Dimensional Operational Theories, arXiv:2602.09056 (2026) — NSS + normal steering + σ\sigma-affinity force the Born form via GNS; single-system rule only, not composition. ESTABLISHED claim; peer review unconfirmed
  • arXiv:2509.12911 (PRL), Uniqueness of purifications is equivalent to Haag duality — Haag duality \Rightarrow local tomography only for factors; local tomography \leftrightarrow subfactor irreducibility. ESTABLISHED, web-confirmed