EXTRACTED TEXT — a prose aid; equations and symbols may be mis-transcribed. Consult the unchanged PDF and exact source. PAGE 1 Causal Self-Diagnosis with Noisy Tests Observation Laws, Irreversible Access, and Task Recovery Research development draft prepared for Brian Theory AI-assisted derivation, computation, and independent internal review 5 November 2026 Version 0.3 Abstract A controller can compensate for a malfunction while remaining unable to attribute it to its actuator or environment. We study this distinction in finite diagnostic models with specified experiment permissions. Positive readout likelihoods preserve exact posterior support, so a fixed support-only permission rule restricts all acquisition to the initially available library. For history-dependent access, initial statistical separation is insufficient. With static known finite-alphabet channels and always-legal idempotent repetition, an oracle revealing each test’s complete observation-law class characterizes arbitrarily reliable finite diagnosis. The closure of attainable randomized terminal decision channels is the convex hull of finite legal oracle-tree channels, giving Bayes and minimax limits. Four hidden states are minimal for the exhibited gap between reliable finite-policy families and one ongoing consistent policy. Known persistent nuisance and sampling prices have distinct, explicitly delimited extensions. We compare order-complex homotopy preservation with a specified recovery task. Neither implies the other; minimal three-state witnesses and a task-dependent availability predicate make this distinction concrete. A conditional implementation bridge states the additional phys- ical obligations. An anchored motor model and independent stateful calculations expose effects of initial motion, persistent preparation error, heat, and depleted resources. The original 48,000 episodes are supplemented by 240,000 independent simulated episodes and exact confirmatory- power calculations. Five simulated specialist reviews and two cross-reviews sharpen the proofs, source attribution, and experimental scope. A reconstructed historical witness challenges one printed necessity claim under its exact definition. The paper concerns functional diagnosis. It claims neither subjective awareness, hardware validation, external peer review, nor publication priority. Status. A working paper, not a submitted or externally reviewed manuscript. Author attribution for submission remains undecided. Proved results refer to the arguments and internal checks here, not formal proof-assistant certification. 1 PAGE 2 Contents 1 Useful control without causal self-diagnosis 3 2 Related work and limits of the novelty claim 3 3 A fixed-state diagnostic contract 4 4 What noisy support permits 5 5 Cumulative orders: a finite oracle characterization 6 6 Complete observation laws and attainable decisions 9 7 Self, world, and the decision that needs the distinction 12 8 Cost and risk as parts of the contract 14 9 Exact experiments and independent checks 15 10 From formal permission to physical experiments 17 11 Preserving a specified recovery task 19 12 Observation fidelity and finite-horizon robustness 22 13 An anchored motor experiment: model and test protocol 23 14 Stateful experiments, resource limits, and confirmatory power 26 15 Conclusions and remaining boundaries 30 A Assumption failures and boundary cases 30 B V erification and novelty ledger 32 C Reproduction 33 D A source-audit witness for a printed necessity claim 33 E Historical coverage and remaining originals 35 F Simulated review and revision ledger 35 2 PAGE 3 1 Useful control without causal self-diagnosis Suppose an action produces the opposite of its intended outcome. The actuator may have reversed, or the environment may have reversed its effect. A controller can learn the resulting input–output relation while remaining unable to attribute the change. That ambiguity matters only for particular downstream tasks: repair, forecasting after an intervention, or transfer may require distinctions that immediate control does not. We use causal self-diagnosis operationally: estimating a variable assigned to the system’s own mechanism within a specified causal model and intervention interface. The assignment to self is supplied by the physical model, not recovered from a statistical partition alone. No criterion for consciousness is proposed. Two B-Theory manuscripts motivate the study. R4 compares actuator-tracking controllers under a known finite model. Its explicit, compiled, and external trackers implement the same mapping; gains over restricted baselines concern evidence processing, not the self-model label [ 25]. The acquisition report distinguishes a sufficient predictive representation from one that permitted observations can actually acquire [ 31]. We connect these questions by adding noisy, potentially confounded diagnostic channels and explicit losses. The central modeling issue is what a test changes. A noisy answer changes belief weights but need not eliminate a state. A test may also change a formal observation order, or an intervention may change the physical system. These are different updates. Treating them as interchangeable can produce an incorrect theorem. The paper studies diagnostic access under explicit constraints. It gives a support-only reduction, develops an ideal-oracle characterization for cumulative availability, connects identifiable distinc- tions to regret and interventions, and tests the physical interpretation with counterexamples, an implementation contract, and a proposed motor experiment. Exact computations and internal in- dependent checks accompany the arguments. The support-only theorem and statistical tools are elementary specializations of established ideas. We give a finite decision-tree characterization for static diagnostic models with irreversible query availability and idempotent repeats, combining adapted simulation, finite-state common randomness, and amplification. Section 6 extends this reduction to complete observation laws and terminal channels. The cumulative-order results are derived here as a concrete extension; this does not assert publication priority. 2 Related work and limits of the novelty claim Model-based diagnosis already treats competing fault explanations and discriminating measure- ments. Reiter’s consistency-based account [ 27] and de Kleer and Williams’ probabilistic measure- ment selection [ 8] are direct antecedents. Naming an actuator variable does not create a new diagnosis paradigm. Controlled sensing and active sequential hypothesis testing select informative actions under error and cost criteria [ 7, 21, 20]. Pairwise separation by action-conditioned laws is an established identifi- ability condition. We restrict the executable library and ask for labels grouping hypotheses. This is closely related to equivalence-class determination [ 11] and decision-region determination [ 15]. Exact version-space termination eliminates incompatible hypotheses. Our repeated full-support setting permits arbitrarily reliable finite reporting while generally forbidding zero-error finite certification. Stochastic diagnosis already distinguishes exact fault certainty from asymptotically high con- fidence [ 33, 2]. The recovered 2005 original gives a sufficient AA-diagnosability condition and examples showing it is not necessary. Active information acquisition and information-state dy- 3 PAGE 4 namic programming are also established [ 34]; its erratum makes policies measurable relative to the observations they generate. The recovered unreliable-observation paper [ 35] motivates the focused source-level check in Appendix D. Later criteria require care about the fault-prefix quantifier [ 6]; the relevant 2017 full theorem remains unavailable [ 32]. We claim neither the support/confidence distinction nor active diagnostic sensing as new. Qualitative POMDP safety uses belief supports rather than positive probability magnitudes [ 16, 5]. High-probability safe exploration instead uses confidence bounds under additional assumptions [29]. A zero-risk support rule and a small failure-probability rule are different problems. Our topological predicate is not a physical safety theorem. Identifiability relative to observations and interventions is standard causal reasoning [ 23, 13]. Our XOR model concerns parameter attribution, not graph discovery or an average causal effect. Predictive state representations explain why useful prediction need not recover a privileged latent description [ 19]. Robotic self-modeling and damage recovery have substantial experimental prece- dent [ 4]; we supply no robot data or architectural superiority claim. Repetition and majority voting to simulate a noiseless decision tree are established [ 10]. Com- paring a noiseless experiment with its noisy garbling is classical [ 3]; sequential versions also exist [9]. Renou and Venel explicitly treat restrictions on feasible histories, controlled information, and early actions constraining later access [ 28]. Their Section 4.3 is a particularly close antecedent. This is a close antecedent to constrained experiment comparison; our claim is a finite specialization with legality-preserving simulation. Recent precedence-constrained decision trees are particularly relevant [ 30]. Their monotone prerequisites differ from the irreversible incompatibilities in our cumulative inclusion rule. This distinction is not a completed priority assessment. 3 A fixed-state diagnostic contract Let H be finite and nonempty, with known prior (h)> 0 for every state. The hidden diagnostic target is fixed during the experiments in Sections 4–5. Concrete apparatus coordinates may change, as modeled separately in Section 13. A finite library E contains repeatable tests. Test e has finite alphabet Ye and known kernel Ke(y jh), with Ke(y jh)> 0 ( e 2 E; y 2 Y e; h 2H): (1) The conditional law of each observation given the entire past, selected test, and state is this kernel. Repetition therefore supplies fresh information; one-time marginal distributions alone are not the assumption. A policy is one history-dependent selection, stopping, and reporting rule used under every state. Private randomness is independent of the state and noise. All tests and answers are recorded. The target is ` :H ! L. States with the same label need not share observation laws. Letbt be the posterior and St = fh :bt(h)> 0g its exact support. A support-only admissibility rule is any fixed predicate L : E  (2H n f∅g) ! f0; 1g: Teste is allowed only if L(e;S t) = 1 , evaluated before its answer. No downward monotonicity is assumed. Robust physical safety L(e;S ) = 1fS  Aeg, for a set of safe states Ae, is one special case; formal structural rules may mean something else. Definition 3.1. A label is reliably acquirable if for every  >0 there is a legal policy with a finite deterministic observation bound and maxh Ph(b` 6=`(h)) . This is a family of finite procedures, not a zero-error stopping certificate. 4 PAGE 5 For finite H and positive prior, vanishing maximum, statewise, and Bayes errors are equivalent for a sequence of policies: min max h errh  X h (h)errh  max h errh;  min = min h (h)> 0: Guarantees concern the supplied model, not unspecified noise, omitted faults, or a continuum of arbitrarily close alternatives. 4 What noisy support permits Theorem 4.1 (Support persistence) . After every finite reachable history, St =H. The executable library is always E0 = fe :L(e;H ) = 1 g. Conversely, every adaptive policy using only E0 is legal. Proof. Posterior mass is proportional to (h)Qt s=1Kes(ys jh), a product of positive terms. Com- mon policy factors cancel because identical histories receive identical selection probabilities un- der every state, including randomized policies. Substitute St = H into L. No monotonicity is needed. Define h 0 g when Ke( j h) = Ke( j g) for every e 2 E 0. This equivalence of experimental laws is different from posterior support. Theorem 4.2 (Labels and residual error) . A label is reliably acquirable exactly when it is constant on every 0 class. If h 0g but`(h) 6=`(g), every legal policy satisfies errh +err g  1. The limiting optimal Bayes error is R∗ = 1 X C∈H/≡0 max l∈L X h∈C ℓ(h)=l (h): (2) Proof. For an equivalent pair every legal test has the same response law. Induction gives identical adaptive transcript laws, including stopping and reports. The two correct labels are disjoint events under this common law, proving the error bound and necessity. For sufficiency, cycle through all tests in E0, use maximum likelihood over H, and report the selected state’s label. The bound below tends to zero when all differently labelled pairs are separated. A constant target needs no tests; an empty library can acquire only a constant target. An oracle revealing the equivalence class cannot worsen performance. Within a class, all tran- script likelihoods agree and posterior ratios remain the prior ratios. Its best report is the largest prior label mass, giving ( 2). Cycling consistently learns the class and approaches this oracle er- ror. 4.1 Sample bounds and stopping distinctions For each pair define affinity e(h;g ) =P y p Ke(y jh)Ke(y jg). With deterministic sample counts ne, maximum likelihood satisfies Phf`(bh) 6=`(h)g  X g:ℓ(g)̸=ℓ(h) Y e∈E0 e(h;g )ne: (3) A wrong-label maximizer has likelihood at least that of h. Markov’s inequality for the square root of its likelihood ratio gives the product of affinities; apply the union bound. Affinity equals one exactly when the two laws agree. 5 PAGE 6 If each test is used m times, define Cmin = min ℓ(h)̸=ℓ(g) P e loge(h;g )> 0 for a nonconstant separated label. Maximum error is at most (jHj 1)e−mCmin. Summability shows that reports under one infinite cycling policy eventually remain correct almost surely. The agent need not know when its last error occurred. In contrast, no nonconstant label has a zero-error procedure terminating almost surely under ev- ery state. Finite transcript laws are mutually absolutely continuous, as are finite stopped transcript laws by decomposing an event over the possible stopping times. A label reported with positive prob- ability under one state therefore has positive reporting probability under a differently labelled state. Unbounded expected time does not remove this obstruction when termination remains almost sure. The results extend to standard Borel observation spaces when each test’s laws are mutually absolutely continuous across states. Use a common dominating measure and positive densities almost everywhere. Support persistence then holds almost surely simultaneously over finite times. Equal topological support alone is insufficient (Appendix A). 4.2 A noiseless RF example and an explicit noisy lift The acquisition manuscript thins a finite order with an oriented Boolean test: retain u v only if q(u)  q(v). The test is admissible when the order-complex inclusion is a homotopy equivalence [31]. For P = fag + fx;y g + fzg, root admissibility is q(a) q(z); every test is legal on the middle antichain. This is a structural rule, not a physical safety guarantee. In coordinate order (a;x;y;z ) take q = 0110; r = 1100; ` = (0; 1; 2; 0): (4) Noiselessly, legal query q returns zero on a homogeneous label-zero branch, or one on fx;y g, where r is legal and separates labels one and two. Now define a support-reset noisy lift : after each noisy answer, evaluate the predicate on the original order induced on exact posterior support. Every query returns its nominal bit through a fresh known BSC with 0 < " <1=2. Support remains P , only q is available, and its laws at x;y agree. Limiting uniform-prior Bayes error is 1=4; limiting minimax error is 1=2. Arbitrarily small positive noise changes feasibility under this exact support convention. No general impossibility of noisy active learning follows. An additional supplied test s = 0100 is root legal. The q;s signatures separate the labels. Repeating each n times and using majority decoding gives error at most 2 exp[2n(1=2 ")2]. At " = 1=5;n = 21 the bound is 0:0456454; using the exact binomial tail gives the sharper union bound 0:00193939. This lift is a choice: a noisy answer does not make prior tests constant on its support, so the noiseless branch-cancellation reasoning does not apply. Retaining previous structural changes gives a different model. 5 Cumulative orders: a finite oracle characterization Let P be a finite poset with carrier H, and E a finite set of nominal Boolean tests qe :H ! f0; 1g. The physical hidden state is fixed. Let J  E record the distinct executed tests. Define an order on the full carrier by u J v ( ) u P v and qe(u) qe(v) for every e 2J: 6 PAGE 7 Teste is legal at J when A(J;e ) = 1f∆(PJ∪{e}),! ∆(PJ ) is a homotopy equivalence g = 1: (5) Repeating an executed test is structurally idempotent and legal. Each repetition returns a fresh independent BSC observation with common known 0<"< 1=2. The structural carrier is never reduced by a noisy answer. Initial-state support remains full, but the order can change. Theorem 4.1 therefore does not freeze A(J;e ). Example 5.1 (Root separation is insufficient) . On the diamond a