REVIEW 2 major objections 5 minor 62 references
Entropy-regularized equilibria become exponentially sensitive to model error when the control graph has a positive feedback cycle, changing the statistical resolution boundary from a power law to order 1/log n.
Reviewed by Pith at T0; open to challenge. T0 means a machine referee read the full paper against a public rubric. the ladder, T0–T4 →
T0 review · deepseek-v4-flash
2026-08-01 15:56 UTC pith:B2KOH3NF
load-bearing objection A serious, honestly hedged theory paper: real new results on temperature-explicit susceptibility for EEHJB, with the main soft spot being that exponential amplification is proven for exact models plus a conditional abstract theorem, not for general state-dependent EEHJB. the 2 major comments →
Feedback Cycles in Exploratory Equilibria
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
The paper claims that the derivative of an entropy-regularized equilibrium policy with respect to model parameters is governed by a backward Volterra resolvent u = τ^{-1}S(c + Ku), and that its low-temperature size is set by the causal graph of the system. On a directed acyclic graph the response is exactly polynomial, Θ(τ^{-(L+1)}); a positive feedback cycle produces an exponential factor E_β(g(T-t)^β/τ^q) under an aligned cone condition. In the bounded uniformly elliptic model the susceptibility matrix is χ_τ(t) = (v/τ) exp{(-νI + vK/τ)(T-t)}, and the paper shows that closing one positive cycle changes the root-n linear-response boundary from a power law to order 1/log n, with an exact Lam
What carries the argument
The load-bearing object is the causal Volterra resolvent: the policy tangent solves u = τ^{-1}S(c + Ku), where S is the centered Gibbs covariance operator and K is the future-policy-to-current-score derivative. The influence kernel is measured by a fractional integral I^α_{T-} of order α ∈ (0,2], so the resolvent series is bounded by the Mittag-Leffler function E_α(κ(T-t)^α/τ). In block form, powers of A = SK count directed walks: an acyclic graph satisfies A^{L+1}=0, terminating the series after the longest path, while a positive cycle contributes the factor E_β(g(T-t)^β/τ^q). This same machinery powers the fixed-temperature delta method.
Load-bearing premise
The exponential amplification claim rests on an assumed 'aligned positive mode'—a cone preserved by the feedback operator with a temperature-independent test path—which the paper verifies only for special bounded-diffusion models, so without that condition negative feedback could damp the response and no exponential growth need occur.
What would settle it
In the exact affine model with β=T=1 and ξ_n = Z/√n, integrate (5.5)–(5.7) at the Lambert-W scale τ*_n = βT/W(βT√n) for n ≥ 10^8; Theorem 5.2 predicts m(0) has a nondegenerate random limit with mean about 0.52, while m(t) for fixed t>0 converges to 0. A distribution converging to a point mass, or a nonvanishing later-time response, would refute it.
If this is right
- On a directed acyclic graph of longest path L, the equilibrium susceptibility is Θ(τ^{-(L+1)}); along a positive cycle it is at least of exponential order, so closing one edge can change the small-temperature scaling.
- The root-n statistical resolution boundary for learned-model noise is of order (log n)^{-α} in general and order 1/log n when a positive cycle with α=1 is present.
- At fixed τ>0, the local equilibrium branch is twice differentiable in finite-dimensional model parameters, so function-valued delta-method inference for equilibrium policies is justified.
- In the bounded diffusion model, right-endpoint time discretization along a cyclic Perron mode is relatively consistent exactly when Nτ^2→∞; for a DAG, N→∞ suffices without coupling to τ.
- The affine model has an exact phase transition at τ*_n = βT/W(βT√n) ~ 2βT/log n, at which the initial policy has a nondegenerate random limit while every fixed later-time policy converges to the reference mixture.
Where Pith is reading between the lines
- If the exponential amplification holds generally, then entropy-annealing in cyclic control environments will not achieve root-n accuracy: n^{-1/2} model errors, harmless on a DAG, leave order-one policy errors on a cycle. A practical corollary is to estimate the causal return structure before cooling.
- The Lambert-W scale implies that for a cyclic system, achieving a fixed statistical precision at temperature τ requires a sample size exponential in βT/τ—a quantitative prediction testable in tabular or linear-quadratic experiments.
- The lower bound's dependence on the invariant-cone condition (assumed, not derived) suggests that negative feedback can mask cycle amplification; characterising the largest class of state-dependent models in which the exponential rate is actually attained remains an open problem, and the paper's e^{C/τ^2} general bound hints the true rate may be even worse in some models.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. This paper studies the sensitivity of entropy-regularized equilibria in time-inconsistent stochastic control to perturbations of the model parameters, with emphasis on low-temperature amplification. The core objects are a backward Volterra resolvent for the derivative of the equilibrium policy and a graph-theoretic decomposition of the causal influence operator. Under an abstract fractional-causal-influence assumption (Assumption 3.2), the paper proves an upper bound of Mittag-Leffler type; under additional cone/order hypotheses (3.12)-(3.14) it proves a matching lower bound. The block decomposition yields a dichotomy: on acyclic influence graphs the susceptibility is polynomial in 1/tau, whereas a positive cycle can produce exponential growth. The paper then proves fixed-temperature C^2 differentiability of the EEHJB equilibrium branch and a function-valued delta method, with an e^{C/tau^2} general stability certificate. Two explicit models - an affine two-action model and a bounded trigonometric diffusion - realize the rates, including a Lambert-W critical temperature for root-n reward noise and a discrete-time mesh-stiffness threshold N tau^2 -> infinity along a cyclic Perron mode. The numerical section reports reproducible experiments with deterministic verification.
Significance. If the results hold, they identify a new and concrete mechanism: the topology of causal feedback cycles, not just the 1/tau Gibbs factor, controls the conditioning of exploratory equilibria at low temperature. The path-cycle distinction is sharp and quantitatively explicit (Theta(tau^{-(L+1)}) vs e^{C/tau}), with a matching nonlinear selection phenomenon in a bounded uniformly elliptic model. The paper is unusually careful: the abstract theorems are stated with explicit hypotheses, the exact models are solved in closed form, the proofs are self-contained relative to stated assumptions, and the numerical code is archived and deterministic, with no fitted constants. The main limitation is that the exponential lower bound is conditional on cone conditions verified only for the exact models; this does not invalidate the exact-model results but restricts the generality of the advertised cycle-induced amplification.
major comments (2)
- [§3, Thm 3.4–Cor 3.7; §4, Assump. 4.1–4.2; §5.2] The exponential lower bound (3.15) and the resolution boundary (Cor 3.5, Cor 3.7) are conditional on the cone/order conditions (3.12)–(3.14). These are assumed, not derived from the EEHJB hypotheses of Section 4; the only verification is for the constant-coefficient bounded-diffusion model in §5.2 (Perron cone with ψ(t)=e^{νt}r). For the state-dependent parabolic setting of §4 the natural causal order is α=1/2 from (4.11), and no ψ, cone, or κ_- is constructed. The scalar example following Thm 3.3 (A=-κ∫) shows that without the sign condition the response is damped, so the cone condition is essential. Consequently the paper establishes the e^{C/τ} amplification and the 1/log n boundary for an explicit model class plus a conditional abstract statement, not for general state-dependent EEHJB. Please either verify (3.12)–(3.14) for a nontrivial state-dependent class, or state this limitation
- [Abstract; §7] The abstract's sentence 'Closing one positive cycle changes the root-n linear-response boundary from a power law to order 1/log n' is not qualified by the aligned-mode/cone assumptions. Since §7 itself leaves open whether a state-dependent model attains even the e^{C/τ} lower rate (the general parabolic upper bound is e^{C/τ²}), the unqualified phrasing overstates the proven scope. Please amend the abstract and the analogous introduction sentence so that the exact models and the conditional abstract theorem are presented as the proven statements.
minor comments (5)
- [§3, Eq. (3.18)] The 'asymptotic solution' of the canonical balance contains an extra log α in the second-order term. Since only the {1+o(1)} form is claimed, please label it as a leading-order asymptotic solution rather than the exact solution of the displayed equation.
- [§5.1, Eq. (5.3)] The actionwise reward r(y,s,x,a) is not written explicitly; the integrand uses the policy-averaged m^π. State explicitly that r(y,s,x,a)=β(x−y)a, so that the averaged term in (5.3) is the mean reward under π.
- [§6, Prop. 6.1] In the DAG part, the assumption N≥L appears only in the text after the proposition. Move it into the statement for clarity.
- [Title page] 'EXPLORA TOR Y' contains a stray space in the title; please check the typesetting.
- [§6.1 (numerics)] Specify that the 16.2% and 1.32% errors at n=1014 refer to τ_{n,1} and τ_{n,2} in (5.13).
Circularity Check
No significant circularity: the central bounds, graph dichotomy, and statistical scales are derived from explicit assumptions or exact models, and the numerical claims are not fitted to the theory.
full rationale
The derivation chain is self-contained relative to its stated hypotheses. The abstract susceptibility estimates (Thms 3.3–3.4) follow directly from Assumption 3.2 and the explicitly stated aligned-cone conditions (3.12)–(3.14); these are hypotheses, not conclusions forced by the claimed result. The paper does not present the general parabolic upper bound e^{C/τ^2} as a sharp prediction, and it openly states that whether state-dependent models attain the larger rate is open. The exponential amplification and the 1/log n boundary for the bounded-diffusion model come from the exact susceptibility formula (5.19) and its spectral analysis in Cor 5.4, not from fitting any constant. The affine model's Lambert-W critical temperature is obtained by solving the exact equation a_n=1 in Theorem 5.2. The numerical section explicitly states that no constant in a theoretical curve is fitted to the output. The dependence on [14] is background well-posedness for EEHJB systems, and the paper constructs its local equilibrium branch and influence equations directly rather than importing a uniqueness theorem from its own prior work. The skeptical concern that cone conditions (3.12)–(3.14) are verified only for the constant-coefficient bounded-diffusion model is a scope limitation about generality, not a circular reduction: the theorem that uses them states them as assumptions, and the paper does not claim those conditions are consequences of the general well-posedness hypotheses. No fitted-input-called-prediction, self-citation load-bearing, ansatz-smuggling, or renaming pattern is present.
Axiom & Free-Parameter Ledger
axioms (10)
- domain assumption Assumption 3.2: ∃α∈(0,2], κ≥0, C_c such that ∥S_t K v(t)∥ ≤ κ (I^α_{T−}∥v∥)(t) and ∥S_t c[h](t)∥ ≤ C_c ∥h∥.
- domain assumption Assumption 4.1: uniform ellipticity, heat-kernel gradient bounds (s−t)^{−1/2}, C² finite-dimensional parameterization.
- domain assumption Assumption 4.2: uniform comparison envelope ∥V*_M,τ∥_V ≤ B_V and uniform mild-clause bounds over τ∈I.
- domain assumption Theorem 4.7 assumes existence of one mild equilibrium (V0,π0) at θ0.
- ad hoc to paper Cone/order conditions (3.12)–(3.14): AX+⊂X+, w_h⪰c_−ψ, A(fψ)⪰κ_− I^α f ψ.
- domain assumption Cor 5.5: K≥0 with positive row sums, sup supp μ0 = 1, T < π/2.
- domain assumption Statistical input: √n(θ̂_n−θ0)⇒Ξ and P(θ̂_n∈U)→1.
- standard math Mittag-Leffler positive-axis asymptotics log E_α(z) ∼ z^{1/α} (proved in SM1).
- standard math Fractional integral semigroup identities I^α I^γ = I^{α+γ} and gamma denominators.
- standard math Perron-Frobenius and nonnegative-matrix facts: acyclic nilpotence, ρ(K)>0 on cycles, norm comparisons.
read the original abstract
Entropy regularization smooths equilibrium policies in time-inconsistent stochastic control. At low temperature, the same Gibbs response can strongly amplify errors in learned rewards and dynamics. We show that the derivative of an exploratory equilibrium is governed by a backward Volterra-parabolic resolvent. Along an aligned positive mode, a lower bound has the same exponential order. A block decomposition identifies the source of the amplification: causal paths contribute powers of 1/tau, whereas a positive feedback cycle can produce exponential growth. At fixed temperature, a local equilibrium branch is twice differentiable with respect to finite-dimensional model parameters, which yields a function-valued delta method. A bounded uniformly elliptic diffusion realizes this path-cycle distinction in every finite dimension. Closing one positive cycle changes the root-n linear-response boundary from a power law to order 1/log n; along the cyclic Perron mode, right-endpoint discretization is relatively consistent exactly when N tau^2 -> infinity. An affine model also gives an exact nonlinear transition at the Lambert-W temperature beta T / W(beta T sqrt(n)). Numerical calculations illustrate these rates.
Reference graph
Works this paper leans on
-
[1]
E. Bayraktar, Y.-J. Huang, Z. Wang, and Z. Zhou , Relaxed equilibria for time-inconsistent Markov decision processes , Math. Oper. Res., 50 (2025), pp. 2666--2687, https://doi.org/10.1287/moor.2023.0209. Published online October 23, 2024
arXiv 2025
-
[2]
E. Bayraktar, Z. Wang, and Z. Zhou , Short communication: Stability of time-inconsistent stopping for one-dimensional diffusions , SIAM J. Financial Math., 13 (2022), pp. SC123--SC135, https://doi.org/10.1137/22M1510005
-
[3]
E. Bayraktar, Z. Wang, and Z. Zhou , Stability of equilibria in time-inconsistent stopping problems , SIAM J. Control Optim., 61 (2023), pp. 674--696, https://doi.org/10.1137/22M1496955
-
[4]
A. Berman and R. J. Plemmons , Nonnegative Matrices in the Mathematical Sciences , vol. 9 of Classics in Applied Mathematics, Society for Industrial and Applied Mathematics, Philadelphia, 1994, https://doi.org/10.1137/1.9781611971262
-
[5]
T. Bj \"o rk, M. Khapko, and A. Murgoci , On time-inconsistent stochastic control in continuous time , Finance Stoch., 21 (2017), pp. 331--360, https://doi.org/10.1007/s00780-017-0327-5
-
[6]
T. Bj \"o rk, M. Khapko, and A. Murgoci , Time-Inconsistent Control Theory with Finance Applications , Springer Finance, Springer, Cham, 2021, https://doi.org/10.1007/978-3-030-81843-2
-
[8]
M. Dai, Y. Dong, and Y. Jia , Learning equilibrium mean--variance strategy , Math. Finance, 33 (2023), pp. 1166--1212, https://doi.org/10.1111/mafi.12402
-
[9]
Diethelm , The Analysis of Fractional Differential Equations , vol
K. Diethelm , The Analysis of Fractional Differential Equations , vol. 2004 of Lecture Notes in Mathematics, Springer, Berlin, 2010, https://doi.org/10.1007/978-3-642-14574-2
-
[10]
G. Gripenberg, S.-O. Londen, and O. Staffans , Volterra Integral and Functional Equations , vol. 34 of Encyclopedia of Mathematics and its Applications, Cambridge University Press, Cambridge, 1990, https://doi.org/10.1017/CBO9780511662805
-
[11]
X. Guo, Y. Huang, and X. Yu , Deterministic policy gradient for learning equilibrium in time-inconsistent control problems , 2026, https://arxiv.org/abs/2606.11798
Pith/arXiv arXiv 2026
-
[12]
Hajek , Cooling schedules for optimal annealing , Math
B. Hajek , Cooling schedules for optimal annealing , Math. Oper. Res., 13 (1988), pp. 311--329, https://doi.org/10.1287/moor.13.2.311
-
[13]
Y.-J. Huang, Z. Wang, and Z. Zhou , Convergence of policy iteration for entropy-regularized stochastic control problems , SIAM J. Control Optim., 63 (2025), pp. 752--777, https://doi.org/10.1137/24M1638744
- [14]
-
[15]
R. M. Karp , A characterization of the minimum cycle mean in a digraph , Discrete Mathematics, 23 (1978), pp. 309--311, https://doi.org/10.1016/0012-365X(78)90011-0
-
[16]
Q. Lei and C. S. Pun , Nonlocal fully nonlinear parabolic differential equations arising in time-inconsistent problems , J. Differential Equations, 358 (2023), pp. 339--385, https://doi.org/10.1016/j.jde.2023.02.025
-
[17]
Q. Lei and C. S. Pun , On the well-posedness of Hamilton--Jacobi--Bellman equations of the equilibrium type , 2023, https://arxiv.org/abs/2307.01986. Revised May 2026
Pith/arXiv arXiv 2023
-
[18]
Q. Lei and C. S. Pun , Nonlocality, nonlinearity, and time inconsistency in stochastic differential games , Math. Finance, 34 (2024), pp. 190--256, https://doi.org/10.1111/mafi.12420
-
[19]
A. Leonidov, A. Savvateev, and A. G. Semenov , Quantal response equilibria in binary choice games on graphs , 2019, https://arxiv.org/abs/1912.09584
Pith/arXiv arXiv 2019
-
[20]
N. S. Lesmana and C. S. Pun , A subgame perfect equilibrium reinforcement learning approach to time-inconsistent problems , SIAM J. Financial Math., 16 (2025), pp. 68--122, https://doi.org/10.1137/23M1594510
-
[21]
J. Ma, G. Wang, and J. Zhang , Convergence analysis for entropy-regularized control problems: A probabilistic approach , SIAM J. Control Optim., 64 (2026), pp. 816--842, https://doi.org/10.1137/24M1680039
-
[22]
R. D. McKelvey and T. R. Palfrey , Quantal response equilibria for extensive form games , Experimental Economics, 1 (1998), pp. 9--41, https://doi.org/10.1023/A:1009905800005
-
[23]
Podlubny , Fractional Differential Equations , vol
I. Podlubny , Fractional Differential Equations , vol. 198 of Mathematics in Science and Engineering, Academic Press, San Diego, 1999
1999
-
[25]
C. Reisinger and Y. Zhang , Regularity and stability of feedback relaxed controls , SIAM J. Control Optim., 59 (2021), pp. 3118--3151, https://doi.org/10.1137/20M1312435
-
[26]
D. Sethi, D. S i s ka, and Y. Zhang , Entropy annealing for policy mirror descent in continuous time and space , SIAM J. Control Optim., 63 (2025), pp. 3006--3041, https://doi.org/10.1137/24M166591X
-
[27]
W. Tang, Y. P. Zhang, and X. Y. Zhou , Exploratory HJB equations and their convergence , SIAM J. Control Optim., 60 (2022), pp. 3191--3216, https://doi.org/10.1137/21M1448185
-
[28]
H. V. Tran, Z. Wang, and Y. P. Zhang , Policy iteration for exploratory Hamilton--Jacobi--Bellman equations , Appl. Math. Optim., 91 (2025), 50, https://doi.org/10.1007/s00245-025-10249-3
-
[29]
A. W. van der Vaart , Asymptotic Statistics , vol. 3 of Cambridge Series in Statistical and Probabilistic Mathematics, Cambridge University Press, Cambridge, 1998, https://doi.org/10.1017/CBO9780511802256
-
[30]
Z. Wang, X. Yu, J. Zhang, and Z. Zhou , Equilibrium under time-inconsistency: A new existence theory by vanishing entropy regularization , 2026, https://arxiv.org/abs/2603.10321
Pith/arXiv arXiv 2026
-
[31]
Yong , Time-inconsistent optimal control problems and the equilibrium HJB equation , Math
J. Yong , Time-inconsistent optimal control problems and the equilibrium HJB equation , Math. Control Relat. Fields, 2 (2012), pp. 271--329, https://doi.org/10.3934/mcrf.2012.2.271
-
[32]
N. V. Krylov , Lectures on Elliptic and Parabolic Equations in H \"o lder Spaces , vol. 12 of Graduate Studies in Mathematics, American Mathematical Society, Providence, RI, 1996, https://doi.org/10.1090/gsm/012
doi:10.1090/gsm/012 1996
-
[33]
Tang, Wenpin and Zhang, Yuming Paul and Zhou, Xun Yu , title =. SIAM J. Control Optim. , volume =. 2022 , doi =
2022
-
[34]
Huang, Yu-Jui and Wang, Zhenhua and Zhou, Zhou , title =. SIAM J. Control Optim. , volume =. 2025 , doi =
2025
-
[35]
Ma, Jin and Wang, Gaozhan and Zhang, Jianfeng , title =. SIAM J. Control Optim. , volume =. 2026 , doi =
2026
-
[36]
Tran, Hung Vinh and Wang, Zhenhua and Zhang, Yuming Paul , title =. Appl. Math. Optim. , volume =. 2025 , doi =
2025
-
[37]
Reisinger, Christoph and Zhang, Yufei , title =. SIAM J. Control Optim. , volume =. 2021 , doi =
2021
-
[38]
Bayraktar, Erhan and Wang, Zhenhua and Zhou, Zhou , title =. SIAM J. Control Optim. , volume =. 2023 , doi =
2023
-
[39]
Bayraktar, Erhan and Wang, Zhenhua and Zhou, Zhou , title =. SIAM J. Financial Math. , volume =. 2022 , doi =
2022
-
[40]
and Palfrey, Thomas R
McKelvey, Richard D. and Palfrey, Thomas R. , title =. Experimental Economics , volume =. 1998 , doi =
1998
-
[41]
, title =
Leonidov, Andrey and Savvateev, Alexey and Semenov, Andrew G. , title =. 2019 , eprint =
2019
-
[42]
Here, There and Everywhere: State-Dependent Time-Inconsistent Stochastic Control , year =
Possama. Here, There and Everywhere: State-Dependent Time-Inconsistent Stochastic Control , year =. 2603.22022 , archivePrefix =
-
[43]
Hajek, Bruce , title =. Math. Oper. Res. , volume =. 1988 , doi =
1988
-
[44]
Entropy Annealing for Policy Mirror Descent in Continuous Time and Space , journal =
Sethi, Deven and. Entropy Annealing for Policy Mirror Descent in Continuous Time and Space , journal =. 2025 , doi =
2025
-
[45]
Entropy Regularization Improves Policy Robustness in Continuous-Time Reinforcement Learning , year =
Cao, Jialun and Acero, Fernando and. Entropy Regularization Improves Policy Robustness in Continuous-Time Reinforcement Learning , year =. 2607.03168 , archivePrefix =
-
[46]
Yong, Jiongmin , title =. Math. Control Relat. Fields , volume =. 2012 , doi =
2012
-
[47]
On Time-Inconsistent Stochastic Control in Continuous Time , journal =
Bj. On Time-Inconsistent Stochastic Control in Continuous Time , journal =. 2017 , doi =
2017
-
[48]
Time-Inconsistent Control Theory with Finance Applications , series =
Bj. Time-Inconsistent Control Theory with Finance Applications , series =. 2021 , doi =
2021
-
[49]
Lei, Qian and Pun, Chi Seng , title =. J. Differential Equations , volume =. 2023 , doi =
2023
-
[50]
Lei, Qian and Pun, Chi Seng , title =. Math. Finance , volume =. 2024 , doi =
2024
-
[51]
2023 , eprint =
Lei, Qian and Pun, Chi Seng , title =. 2023 , eprint =
2023
-
[52]
Dai, Min and Dong, Yuchao and Jia, Yanwei , title =. Math. Finance , volume =. 2023 , doi =
2023
-
[53]
Lesmana, Nixie Sapphira and Pun, Chi Seng , title =. SIAM J. Financial Math. , volume =. 2025 , doi =
2025
-
[54]
Bayraktar, Erhan and Huang, Yu-Jui and Wang, Zhenhua and Zhou, Zhou , title =. Math. Oper. Res. , volume =. 2025 , doi =
2025
-
[55]
2026 , eprint =
Huang, Yu-Jui and Yu, Xiang and Zhang, Keyu , title =. 2026 , eprint =
2026
-
[56]
2026 , eprint =
Wang, Zhenhua and Yu, Xiang and Zhang, Jingjie and Zhou, Zhou , title =. 2026 , eprint =
2026
-
[57]
2026 , eprint =
Guo, Xin and Huang, Yijie and Yu, Xiang , title =. 2026 , eprint =
2026
-
[58]
2010 , doi =
Diethelm, Kai , title =. 2010 , doi =
2010
-
[59]
Podlubny, Igor , title =
-
[60]
1990 , doi =
Gripenberg, Gustaf and Londen, Stig-Olof and Staffans, Olof , title =. 1990 , doi =
1990
-
[61]
, title =
Berman, Abraham and Plemmons, Robert J. , title =. 1994 , doi =
1994
-
[62]
, title =
Karp, Richard M. , title =. Discrete Mathematics , volume =. 1978 , doi =
1978
-
[63]
, title =
van der Vaart, Aad W. , title =. 1998 , doi =
1998
-
[64]
Krylov, N. V. , title =. 1996 , doi =
1996
discussion (0)
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