ZFCρ Thermodynamics Paper VI: Causal Correlation Volume, Tail-Active Multiplicative Coupling, and the Conditional Derivation of the Channel-Normalized Winding Ratio
ZFCρ热力学论文 VI:因果相关体积与通道归一化卷绕比的条件性推导
Thermodynamics Paper V (DOI: 10.5281/zenodo.19649780) established the empirical dynamical law q = 1 + n_ch · τ_dec / T but did not explain why K equals the channel-normalized winding ratio. This paper provides a conditional derivation and characterizes the formula's applicability boundary through cross-domain positive and negative example systems. The derivation proceeds in four steps. (1) Lemma 1: the causal correlation volume of an exponential ACF equals τ_dec exactly. (2) Lemma 2: the Laplace transform of an exponential lifetime is precisely the resolvent 1/(1+c) — this is the key bridge connecting causal slots to Thermo IV's shielding layers. (3) Proposition 1: under conditions A1–A6 (where A5 is subdivided into exponential survival, exposure attenuation, and Markov-renewal factorization), each channel's effective shielding depth is K_dyn = T/(n_ch · τ_dec), yielding q = 1 + n_ch · τ_dec / T via Thermo IV's exact interpolation family (conditional theorem). (4) Proposition 2: asymmetric channel generalization with K_i = α_i · T / τ_i, reducing to the symmetric formula. A Fokker-Planck zero-flux condition provides a consistency layer. Positive examples and boundary positives across multiple dynamical classes support the formula: the Brusselator chemical oscillator (n_ch = 2, 14 parameter points, MAE = 0.022) and the symmetric extended Brusselator (n_ch = 3) serve as strong positives; the Selkov glycolysis model (n_ch = 2, weakly tail-active) and an FHN-parameterized synthetic oscillator (n_ch = 2) serve as boundary positives. Six negative example systems delineate the applicability boundary: chaotic systems (Lorenz), relaxation oscillation (Goodwin), bounded coupling (Repressilator), and single-variable nonlinearity (x², x³) each violate distinct necessary conditions. Core finding: q > 1 requires two-variable multiplicative coupling, but not any multiplicative coupling. Selkov possesses an x²y term, yet that term saturates along the nullcline (x²y → b), producing no heavy tail. Brusselator's x²y does not saturate along its nullcline (x²y ~ bx) and remains active in the tail. What matters for "tail-active" is not algebraic form but whether the multiplicative term saturates in the dynamical tail region. ---
Abstract
Thermodynamics Paper V (DOI: 10.5281/zenodo.19649780) established the empirical dynamical law q = 1 + n_ch · τ_dec / T but did not explain why K equals the channel-normalized winding ratio. This paper provides a conditional derivation and characterizes the formula's applicability boundary through cross-domain positive and negative example systems.
The derivation proceeds in four steps. (1) Lemma 1: the causal correlation volume of an exponential ACF equals τ_dec exactly. (2) Lemma 2: the Laplace transform of an exponential lifetime is precisely the resolvent 1/(1+c) — this is the key bridge connecting causal slots to Thermo IV's shielding layers. (3) Proposition 1: under conditions A1–A6 (where A5 is subdivided into exponential survival, exposure attenuation, and Markov-renewal factorization), each channel's effective shielding depth is K_dyn = T/(n_ch · τ_dec), yielding q = 1 + n_ch · τ_dec / T via Thermo IV's exact interpolation family (conditional theorem). (4) Proposition 2: asymmetric channel generalization with K_i = α_i · T / τ_i, reducing to the symmetric formula. A Fokker-Planck zero-flux condition provides a consistency layer.
Positive examples and boundary positives across multiple dynamical classes support the formula: the Brusselator chemical oscillator (n_ch = 2, 14 parameter points, MAE = 0.022) and the symmetric extended Brusselator (n_ch = 3) serve as strong positives; the Selkov glycolysis model (n_ch = 2, weakly tail-active) and an FHN-parameterized synthetic oscillator (n_ch = 2) serve as boundary positives. Six negative example systems delineate the applicability boundary: chaotic systems (Lorenz), relaxation oscillation (Goodwin), bounded coupling (Repressilator), and single-variable nonlinearity (x², x³) each violate distinct necessary conditions.
Core finding: q > 1 requires two-variable multiplicative coupling, but not any multiplicative coupling. Selkov possesses an x²y term, yet that term saturates along the nullcline (x²y → b), producing no heavy tail. Brusselator's x²y does not saturate along its nullcline (x²y ~ bx) and remains active in the tail. What matters for "tail-active" is not algebraic form but whether the multiplicative term saturates in the dynamical tail region.
§1 Problem: Why Does K Equal the Channel-Normalized Winding Ratio?
1.1 The empirical law from Thermo V
Thermo V [1] established
$$q = 1 + \frac{n_{\text{ch}} \cdot \tau_{\text{dec}}}{T}$$
and verified it across a seven-point scan of the Brusselator bifurcation parameter (MAE = 0.022). The formula requires only two macroscopic timescales — oscillation period T and radial decay time τ_dec — and no sampling step τ.
Thermo V did not explain why K equals T/(n_ch · τ_dec). The formula's status was empirical dynamical law.
1.2 This paper's question
From what physical principle does it follow that the effective feedback order in a continuous-time oscillator equals the number of causal correlation volumes that fit into each channel's per-period time budget?
1.3 Contributions
(1) Conditional derivation: Lemma 1 (exact) + Lemma 2 (exact, exponential-slot resolvent bridge) + Proposition 1 (conditional theorem) + Proposition 2 (asymmetric generalization) + FPE consistency layer.
(2) Strong positives: Brusselator (chemistry, n_ch = 2), symmetric extended Brusselator (chemistry, n_ch = 3). Boundary positives: Selkov (glycolysis, n_ch = 2, weakly tail-active), FHN-parameterized synthetic oscillator (n_ch = 2).
(3) Negative boundary controls: Lorenz (chaotic), Goodwin (relaxation), Repressilator (bounded coupling), Selkov low-noise (insufficient exploration), single-variable x²/x³ (no two-variable coupling).
(4) Formal graded definition of tail-active multiplicative coupling (Definition 2a/2b/2c) — explaining why Selkov's x²y does not produce q > 1 while Brusselator's does.
§2 Conditional Derivation
2.1 Exact input from Thermo IV
Thermo IV [2] established the exact interpolation family:
$$e_q(-x) = \left(1 + \frac{x}{K}\right)^{-K}, \quad q = 1 + \frac{1}{K}$$
and the discrete shielding theorem: if total control x is equally partitioned across K resolvent layers, each coupling x/K, the total kernel is (1 + x/K)^{-K}.
This paper does not re-derive the Tsallis kernel. It explains why K = T/(n_ch · τ_dec) in continuous-time oscillators.
2.2 Lemma 1: Causal correlation volume and renewal slots
Lemma 1. Let the pure-decay component of the radial memory kernel be C_dec(t) = C_dec(0) · e^{-t/τ_dec} (t ≥ 0). Define the one-sided causal correlation time:
$$\tau_+ := \int_0^\infty \frac{C_{\text{dec}}(t)}{C_{\text{dec}}(0)} dt$$
Then τ₊ = τ_dec.
Status: Exact.
Definition 1 (causal renewal slot). In a time window of length L, if radial memory is dominated by the exponential kernel e^{-t/τ_dec}, the effective number of causal slots is N_slot(L) := L / τ_dec.
Lemma 1 and Definition 1 together establish τ_dec as the unit length of a causal memory volume and use that unit to count how many independent causal slots fit inside any time window L.
2.3 Lemma 2 and Proposition 1: Exponential-slot resolvent screening
Lemma 2 (exponential-slot resolvent lemma). Let a causal slot's normalized lifetime be U := t/τ_dec, with exponential distribution p(U) = e^{-U} (U ≥ 0). If tail-active f/r screening within the slot attenuates a residual signal at dimensionless intensity c ≥ 0 (conditional transfer factor e^{-cU} given lifetime U), then the slot-averaged transfer function is
$$R(c) := \mathbb{E}[e^{-cU}] = \int_0^\infty e^{-cU} e^{-U} dU = \frac{1}{1+c}$$
Status: Exact under exponential-slot assumption.
Lemma 2 is the key bridge of the entire derivation: it connects an exponential-lifetime causal slot to Thermo IV's single resolvent layer. The resolvent is not an arbitrary choice but the characteristic Laplace transform of exponential renewal. For comparison: a deterministic lifetime (U = 1) gives e^{-c} (Boltzmann); a gamma lifetime (U ~ Γ(a,1)) gives (1+c/a)^{-a}; a → ∞ recovers Boltzmann.
Proposition 1. Consider a stable state-coupled oscillator satisfying:
A1. A stable limit cycle with period T.
A2. n_ch admissible active channels.
A3. Each channel receives an effective causal time budget L_ch = T/n_ch per period. (Structural assumption: A3 is an approximation under phase-averaged symmetry. On a stable limit cycle, channels co-evolve at different phases rather than strictly alternating in time. A3 should be understood as equal-share causal contribution under phase averaging.)
A4. Radial memory is dominated by an exponential pure-decay mode with time constant τ_dec.
A5a. Tail-relevant radial memory has an exponential causal survival kernel: S(t) = e^{-t/τ_dec}.
A5b. Within one normalized slot lifetime U = t/τ_dec, tail-active f/r screening acts at dimensionless intensity c, yielding conditional transfer e^{-cU}.
A5c. Successive slots renew by Markov-renewal factorization: multi-slot transfer is multiplicative.
A6. Under phase averaging, slots within each channel equally share total control x.
Then each channel's effective shielding depth is
$$K_{\text{dyn}} = \frac{T}{n_{\text{ch}} \cdot \tau_{\text{dec}}}$$
and the channel kernel is (1 + x/K_dyn)^{-K_dyn}, giving
$$q = 1 + \frac{n_{\text{ch}} \cdot \tau_{\text{dec}}}{T}$$
Derivation. By Lemma 1, one causal slot has length τ_dec. By A3, each channel's per-period budget is T/n_ch, giving K_dyn = (T/n_ch)/τ_dec slots. By Lemma 2 and A5a–A5b, each slot's averaged transfer is R(c) = 1/(1+c), i.e., one resolvent layer. By A5c (Markov-renewal independence), K_dyn slots yield ∏(1+c_j)^{-1}. By A6 (equal sharing), c_j = x/K_dyn, so the total transfer is (1+x/K_dyn)^{-K_dyn}. By Thermo IV's exact identity q = 1+1/K, this gives q = 1 + n_ch · τ_dec / T.
Status: Conditional theorem under A5a–c + structural assumptions A3, A6. A5 is upgraded from physical identification to conditional theorem: "one causal slot = one resolvent screening layer" is no longer metaphor but a corollary of Lemma 2 + Markov-renewal product structure.
2.4 Definition 2: Tail-active multiplicative coupling (graded)
Given canonical energy-like observable E(z) and multiplicative coupling term M(z), define the tail-projected gain:
$$G_M(e) := \mathbb{E}[\Pi_E M(Z) \mid E(Z) = e]$$
where Π_E M is the projection of M onto the radial/energy direction. In finite data, approximate using high-quantile intervals (e.g., e ∈ [Q₀.₉₀, Q₀.₉₉]). Define the tail-activity index:
$$\alpha_M := \frac{d \log |G_M(e)|}{d \log e} \quad \text{(tail-relevant range)}$$
Definition 2a (strongly tail-active): α_M > 0 asymptotically in the tail-relevant range. The multiplicative term grows with radial departure.
Definition 2b (weakly tail-active): α_M > 0 in an intermediate range but saturates at extreme tail. Fluctuations under sufficient noise can explore the unsaturated edge.
Definition 2c (tail-inactive): α_M ≈ 0 or G_M(e) converges to a constant in the tail-relevant range.
Classification:
- Brusselator x²y: along y-nullcline (y = b/x), x²y = bx, α_M ≈ 1. Strongly tail-active (2a).
- Extended Brusselator: retains x²y. Strongly tail-active (2a).
- Selkov x²y: along y-nullcline (y = b/(a+x²)), x²y = bx²/(a+x²) → b, α_M → 0. Weakly tail-active (2b).
- Repressilator Hill function α/(1+p^n): bounded by α, α_M = 0. Tail-inactive (2c).
- Single-variable x², x³: no two-variable multiplicative coupling. Tail-inactive (2c).
Remark. "Tail-active" is not an algebraic property (whether x²y appears in the equations) but a dynamical property (whether the term continues to grow along the trajectories actually visited by the invariant measure in the tail region).
2.5 Proposition 2: Asymmetric channel generalization
Proposition 2. Let channel i receive time share α_i · T (α_i > 0, Σα_i = 1) with radial decay time τ_i. Then:
$$K_i = \frac{\alpha_i T}{\tau_i}, \quad q_i = 1 + \frac{\tau_i}{\alpha_i T}$$
$$\Omega_{\text{eff}} = \sum_i q_i = n_{\text{ch}} + \sum_i \frac{\tau_i}{\alpha_i T}$$
Under equal readout: q_avg = Ω_eff / n_ch. Symmetric limit α_i = 1/n_ch, τ_i = τ_dec recovers the main formula.
Caveat: q_avg is an arithmetic-average readout approximation. In genuinely asymmetric cases, the macroscopic q is more likely captured by the dominant channel (carrying the largest variance): q_obs ≈ Σ_i w_i · q_i where w_i = Var_i / Σ_j Var_j.
2.6 FPE consistency layer
Phase-averaged one-dimensional effective Fokker-Planck equation [13]:
$$\partial_t P(E,t) = -\partial_E[A(E)P] + \frac{1}{2}\partial_E^2[B(E)P]$$
Zero-flux stationary condition yields P'/P = (2A−B')/B. For P(E) ∝ (1+βE/K)^{-K}:
$$\frac{2A(E) - B'(E)}{B(E)} = -\frac{\beta}{1 + \beta E/K}$$
In Floquet-FPE language: q − 1 = n_ch · ω / (2π · λ_dec), i.e., the ratio of phase rotation rate to radial contraction rate times the channel factor.
Status: Exact condition (FPE zero-flux); consistency check with the main formula.
2.7 Resolvent endpoint and stable corridor
The resolvent endpoint K = 1 corresponds to τ_dec = T/n_ch: each channel's period accommodates exactly one causal slot, giving q = 2. If τ_dec > T/n_ch, then K < 1 and q > 2 — radial memory persists across cycles, and the single-period screening interpretation breaks down. This regime is labeled "beyond the one-cycle absorptive corridor."
Stable applicability corridor: 1 ≤ K < ∞, equivalently 1 ≤ q ≤ 2.
§3 Positive Examples
Positives are graded into strong positives (formula stably applicable, tail-activity clear) and boundary positives (weakly tail-active or synthetic test systems).
3.1 Strong positive: Brusselator (n_ch = 2, chemical oscillation)
Published in Thermo V [1]. dx/dt = a+x²y−(b+1)x, dy/dt = bx−x²y [8]. a = 1, b scanned 2.0–5.0. Tail-active (Definition 2a): x²y along y-nullcline gives x²y = bx (unsaturated).
Representative results (σ = 0.3):
| b | T | τ_dec | K_dyn | q_pred | q_fit | Δq |
|---|---|---|---|---|---|---|
| 2.0 | 5.75 | 0.315 | 9.13 | 1.110 | 1.117 | +0.007 |
| 2.4 | 5.75 | 0.274 | 10.49 | 1.095 | 1.094 | −0.002 |
| 3.0 | 5.76 | 0.276 | 10.43 | 1.096 | 1.091 | −0.005 |
| 3.5 | 6.07 | 0.263 | 11.54 | 1.087 | 1.103 | +0.016 |
| 4.0 | 6.39 | 0.276 | 11.58 | 1.086 | 1.122 | +0.036 |
Core region (b = 2.0–3.5) MAE = 0.008, max |Δq| = 0.016. Full range (b = 2.0–5.0) MAE = 0.022. Deviation increases at b ≥ 4.0 (equal-sharing assumption A6 begins to break down under strong nonlinearity).
3.2 Strong positive: Symmetric extended Brusselator (n_ch = 3)
dx/dt = a+x²y−(b+1)x, dy/dt = bx−x²y+c·(w−y), dw/dt = d·y−e·w. a = 1, b = 3, symmetric coupling c, d, e. The w channel inherits tail-activity from y's x²y dynamics through linear coupling, giving n_ch = 3.
| Coupling | q_fit | q(n=2) | Δq(n=2) | q(n=3) | Δq(n=3) |
|---|---|---|---|---|---|
| c=d=e=0.2 | 1.123 | 1.096 | +0.027 | 1.145 | −0.022 |
| c=d=e=0.3 | 1.131 | 1.096 | +0.036 | 1.143 | −0.012 |
n_ch = 3 is systematically closer than n_ch = 2 under symmetric coupling. The c = d = e = 0.3 case gives clear separation (|Δq| gap = 0.024); c = d = e = 0.2 is weaker (gap = 0.005), requiring error bars for confirmation. The channel-count factor receives cross-system support but does not yet constitute decisive exclusion.
3.3 Boundary positive: Selkov (n_ch = 2, glycolysis, weakly tail-active)
dx/dt = −x+ay+x²y, dy/dt = b−ay−x²y [12]. a = 0.1, b = 0.6.
Selkov's x²y is truncated on the deterministic nullcline (y = b/(a+x²) → x²y → b), classifying as weakly tail-active (Definition 2b). At low noise (σ ≤ 0.10), q ≈ 1.0001 — fluctuations cannot reach the unsaturated region. At σ = 0.3, fluctuations push trajectories away from the nullcline, exploring the tail-active edge: q = 1.070.
q_fit = 1.070, q_pred(n_ch=2) = 1.088, Δq = −0.019.
Selkov's significance lies in demonstrating that tail-activity is determined by the invariant measure's actual tail exploration, not by the algebraic presence of x²y.
3.4 Boundary positive: FHN-parameterized synthetic oscillator (n_ch = 2)
dx/dt = x − x²y/3 − y, dy/dt = ε(x+a−by). ε = 0.08, a = 0.7, b = 0.8, σ = 0.1.
This is a synthetic test system parameterized after FitzHugh-Nagumo [9]: the standard FHN single-variable cubic v³ is replaced by the two-variable coupling x²y. The modified system no longer represents neural dynamics; it tests whether fast-slow systems obey the same period-decay law when tail-active multiplicative coupling is introduced.
q_fit = 1.459, q_pred(n_ch=2) = 1.410, Δq = +0.049.
The q value is substantially higher than Brusselator (1.46 vs 1.09) because τ_dec/T is larger. This confirms the formula operates beyond the q ≈ 1.1 small-deviation regime. Currently a single parameter point; further parameter scans are needed.
3.5 Positive examples summary
| System | Grade | n_ch | q range | Δq | range | Tail-activity | |
|---|---|---|---|---|---|---|---|
| Brusselator | Strong | 2 | 1.09–1.12 | 0.002–0.016 (core) | 2a (strongly) | ||
| Symm. ext. Brusselator | Strong | 3 | 1.12–1.13 | 0.012–0.022 | 2a (strongly) | ||
| Selkov (σ=0.3) | Boundary | 2 | 1.07 | 0.019 | 2b (weakly) | ||
| FHN synthetic | Boundary | 2 | 1.46 | 0.049 | 2a (synthetic) |
§4 Negative Examples: Applicability Boundary
Each negative example exposes a specific necessary condition violation.
4.1 Lorenz attractor (chaos → q = 1)
ẋ = σ(y−x), ẏ = x(ρ−z)−y, ż = xy−βz [14]. σ = 10, ρ = 28, β = 8/3.
q_fit = 1.0001. Under the canonical observable and fitting protocol of this paper, the Lorenz system's rapid mixing due to a positive Lyapunov exponent (λ₊ = 0.906) drives the q-exponential fit back to q ≈ 1.
Exposes condition C1: stable non-chaotic limit cycle is necessary.
4.2 Goodwin oscillator (relaxation → unstable q)
dx₁ = a/(K^n+x₃^n)−bx₁, dx₂ = αx₁−βx₂, dx₃ = αx₂−βx₃ [15]. n = 12.
q_fit varies wildly with noise: σ = 0.005 → q = 1.00, σ = 0.02 → q = 1.50, σ = 0.10 → q = 2.09. No stable window. Strong relaxation switching may break the single (T, τ_dec) kernel dominance.
Exposes condition C2: smooth oscillation (not relaxation switching) is necessary.
4.3 Repressilator (bounded Hill function → q = 1)
dp₁ = α/(1+p₃^n)−p₁, cyclic [16]. n = 3.
q_fit = 1.0001 despite clear oscillation (T ≈ 5, rel_amp = 0.66). Hill function α/(1+p^n) is bounded by α — tail-truncated, producing no heavy tail.
Exposes condition C5: tail-active multiplicative coupling is necessary. Bounded functions do not qualify.
4.4 Selkov low noise (σ = 0.05 → q = 1)
Same Selkov equations, σ = 0.05. q_fit = 1.0001.
Selkov's x²y saturates on the nullcline (x²y → b). At low noise, fluctuations cannot explore the tail-active edge.
Exposes conditions C3/C5: sufficient noise is needed to activate weakly tail-active systems.
4.5 Single-variable nonlinearity (x³, x² → q = 1)
dx = a+x³−(b+1)x, dy = bx−x³ (cubic, single variable): q = 1.0001.
dx = a+x²−(b+1)x, dy = bx−x² (quadratic, single variable): q = 1.0001.
Exposes condition C5: single-variable nonlinearity does not produce q > 1. Two-variable multiplicative coupling is necessary: in x²y coupling, fluctuations in x are amplified by y (mutual amplifiers), producing super-exponential extreme fluctuations.
4.6 Negative examples summary
| System | Type | q | Condition violated |
|---|---|---|---|
| Lorenz | Chaotic | 1.00 | C1 (non-chaotic) |
| Goodwin | Relaxation | Unstable | C2 (smooth oscillation) |
| Repressilator | Bounded coupling | 1.00 | C5 (tail-active) |
| Selkov low noise | Insufficient noise | 1.00 | C3 (moderate noise) |
| x³ single var | Single variable | 1.00 | C5 (two-variable coupling) |
| x² single var | Single variable | 1.00 | C5 (two-variable coupling) |
§5 Applicability Conditions
5.1 Seven necessary conditions
C1. Stable non-chaotic limit cycle. A clear period T must exist. Chaotic mixing via positive Lyapunov exponents drives q toward 1.
C2. Smooth oscillation, not strong relaxation switching. Relaxation oscillation may lack a single stable q window.
C3. Moderate-noise absorptive regime. Inherited from Thermo III [3]. Too little noise: insufficient tail statistics. Too much noise: deterministic structure drowned.
C4. ACF has a clean damped-oscillation + pure-decay decomposition. T and τ_dec must be reliably extractable from the same ACF.
C5. Tail-active multiplicative f/r opposition. The multiplicative coupling term must not saturate in the tail-relevant range (Definition 2a/2b). Strongly tail-active (2a) systems yield strong positives; weakly tail-active (2b) systems yield boundary positives under sufficient noise. Tail-inactive (2c) systems give q = 1.
C6. Active channel count. n_ch counts channels participating in tail-active multiplicative feedback, not raw state-variable count.
C7. Canonical energy-like observable. q must be extracted on r² or equivalent. Thermo IV's reparametrization lemma [2] shows that arbitrary observable choices break q comparability.
5.2 Eligible system class
Tail-active multiplicative state-coupled absorptive oscillators. Not all nonequilibrium systems, not all oscillators, not all systems with multiplicative terms.
5.3 Stable corridor
1 ≤ K_dyn < ∞, equivalently 1 ≤ q ≤ 2. The resolvent endpoint (K = 1, q = 2) corresponds to τ_dec = T/n_ch. Beyond (K < 1, q > 2): cross-cycle memory persistence, outside the one-cycle absorptive corridor.
§6 Status Map and Open Problems
6.1 Status map
| Content | Level |
|---|---|
| q = 1+1/K | Exact (Thermo IV) |
| K-layer equal-weight screening → (1+x/K)^{-K} | Exact (Thermo IV) |
| τ₊ = τ_dec (causal correlation volume) | Exact (Lemma 1) |
| E[e^{-cU}] = 1/(1+c) (exponential lifetime → resolvent) | Exact (Lemma 2) |
| Per-channel T/n_ch (time sharing) | Structural assumption (A3) |
| One causal slot = one screening layer | Conditional theorem under A5a–c |
| K_dyn = T/(n_ch · τ_dec) | Conditional theorem + empirical support |
| q = 1 + n_ch · τ_dec / T | Conditional theorem + empirical support |
| Tail-active graded definition | Definition 2a/2b/2c + examples |
| n_ch from channel time-sharing | Cross-system supported (n=2 and n=3) |
| Asymmetric Ω_eff = n_ch + Σ τ_i/(α_i T) | Conditional corollary (readout approx.) |
| FPE zero-flux condition | Exact (consistency layer) |
| Formula applies to tail-active multiplicative oscillators | Current strongest claim |
| Formula applies to all oscillators | False |
6.2 Open problems
- Empirical testing of A5a–c. Lemma 2 upgraded A5 from physical identification to conditional theorem. Can A5a (exponential survival) and A5c (Markov-renewal independence) be directly tested from Brusselator time-series data, e.g., by checking residual independence across adjacent τ_dec intervals?
- Non-oscillatory systems. The formula depends on oscillation period T. What quantity replaces T in non-oscillatory systems (DP recursion, Schlögl model)?
- General definition of n_ch. Currently defined as the number of channels participating in tail-active multiplicative feedback. How is n_ch determined in more complex systems (multi-frequency, multi-attractor)?
- Experimental verification of asymmetric channels. Proposition 2 provides the unequal-share version K_i = α_i T/τ_i, but no systematic experiment has tested α_i ≠ 1/n_ch.
- Connection to the Lyapunov spectrum. Under weak noise, τ_dec ≈ 1/|λ₋|, giving q = 1 + n_ch/(T · |λ₋|). At the chaos-period boundary, both |λ₋| and T vary simultaneously — does q exhibit phase-transition behavior at that boundary?
- Can tail-activity be predicted from equation coefficients? Currently requires nullcline analysis. Can it be determined from the Jacobian or simpler algebraic properties?
Methods
All SDEs integrated via Euler-Maruyama. Brusselator: dt = 0.005, 2M–3M total steps, 200K–300K burn-in, random seed 42. Extended Brusselator and diagnostic systems: same parameters. Selkov: dt = 0.005. FHN synthetic oscillator: dt = 0.005.
q_fit extraction: CCDF global fit of Tsallis q-exponential on canonical observable r², fitting interval above median (E > median(r²)), Nelder-Mead optimization. Location/scale parameters not fixed. MLE robustification deferred to future work [10, 11].
ACF extraction: from de-meaned x-channel (or f-channel) time series. Fitting model: C(τ) = w₁ · e^{-g₁τ} · cos(ωτ) + w₂ · e^{-g₂τ}. T from ACF first minimum t_min (T = 2 · t_min). τ_dec = 1/g₂. Fitting window: lag 1 to min(150–200 lag points, max_lag).
n_ch determination: for each system, q was predicted with n_ch = n_var−1, n_var, n_var+1; the value closest to q_fit was selected. In all positive examples, the best n_ch equaled the state-variable count n_var.
Error propagation: τ_dec fitting uncertainty (typically 10–15%) propagates directly to q_pred. Pointwise bootstrap CIs are not yet provided; this is an implementation-level degree of freedom (cf. Thermo V §6.2).
References
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