REVIEW 6 minor 51 references
Revealed Information
T0 review · 0 major / 6 minor · reviewed 2026-08-12 · deepseek-v4-flash
Pith's one-line read Fixing the decision maker's utility, an observed action distribution is information-rationalizable exactly when the prior lies in a weighted Minkowski sum of optimal-belief sets—a condition checkable by finitely many linear inequalities.
desk verdict Solid, useful theory: a finite test for information-consistency of action marginals, provided the utility is known; the special-case characterizations are the real payoff. read the letter →
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
The reading
What carries the argument
The load-bearing object is the $\nu_0$-weighted Minkowski sum $M(u,\nu_0)=\sum_a \nu_0(a)\Delta^*_u(a)$, where $\Delta^*_u(a)$ is the polytope of beliefs at which action $a$ maximizes expected utility. Its support function decomposes as the $\nu_0$-weighted sum of the support functions of the $\Delta^*_u(a)$, turning set membership into one inequality per direction. The common refinement of the normal fans of the $\Delta^*_u(a)$ supplies the finite set of directions that define the polytope's H-representation; for monotone-concave problems a dual linear program with adjacent obedience constraints identifies which test functions are needed, giving closed forms for affine and two-step utility differences.
What would settle it
Take a finite decision problem with at least four states and two actions, such as $\Omega=\{\omega_1,\ldots,\omega_4\}$, $u(a_1,\cdot)=0$, $u(a_2,\cdot)=(-9,-5,-1,5)$, and $\nu_0$ uniform. Compute the set of priors satisfying the claimed inequalities of Theorems 2 and 3, and independently compute the set of priors for which the linear program (O, $M_{\mu_0}$, $M_{\nu_0}$) in Definition 1 is feasible, say on a fine grid. If any prior passes the claimed inequalities but has no feasible joint distribution, or vice versa, the H-representation of $M(u,\nu_0)$ is falsified.
Extended reading notes
Core claim
The paper's central claim is that for a fixed utility $u$, the pair $(\mu_0,\nu_0)$ is BCE-consistent—there exists a joint distribution of states and actions with these marginals under which every recommended action is optimal—if and only if $\mu_0\in M(u,\nu_0)=\sum_{a\in A}\nu_0(a)\Delta^*_u(a)$. Equivalently, $\sum_a \nu_0(a)\max_{\mu\in\Delta^*_u(a)} p\cdot\mu \ge p\cdot\mu_0$ for all test directions $p$, and Theorem 1 shows only finitely many directions need be checked: the extreme rays of the one-dimensional cones in the common refinement of the normal fans of the polytopes $\Delta^*_u(a)$. With at most three states, or with affine or two-step utility differences, the test directions have closed forms, yielding the belief-martingale and payoff-martingale inequalities (Theorem 2) and systems of $2|\Omega|$ or $2(|A|-1)$ inequalities (Theorems 3 and 4). The paper also characterizes which Bayes-plausible distributions over posteriors implement a rationalizable $\nu_0$ as those satisfying coalitional inequalities $\sum_{a\in B}\nu_0(a)\ge\sum_{C\subseteq B}\tau_A(C)$ for all $B\subseteq A$, and it uses the characterization for comparative statics and for testing whether one information structure rationalizes choices across several decision problems.
Load-bearing premise
The characterization takes the decision maker's utility function as known or drawn from a parameterized family, and takes the observed action distribution $\nu_0$ to be the exact marginal of one obedient joint distribution; if $u$ is misspecified or the frequencies are noisy estimates, the finite inequality tests do not directly apply.
Editorial extensions
If this is right
- An analyst who knows $u$ but not the prior can read the set of priors consistent with an observed $\nu_0$ directly off the polytope $M(u,\nu_0)$; if $\nu_0$ puts weight on a strictly dominated action, the set is empty and no information structure rationalizes the data.
- For at most three states, the belief-martingale and payoff-martingale inequalities are explicit and finite: they bound the prior from below and require the prior's expected payoff differences to lie within what the observed action frequencies can support.
- Under affine utility differences—which cover every binary-action problem—rationalizability reduces to $2|\Omega|$ linear inequalities, and moving the prior to a $d$-mean-preserving spread preserves rationalizability.
- If the same decision maker is observed in several decision problems, one information structure rationalizes the joint action distribution exactly when that joint distribution is BCE-consistent in the auxiliary decision problem with summed payoffs, extending the test to multi-decision and public-persuasion settings.
- For any rationalizable pair, the Bayes-plausible posterior distributions that implement it are exactly those satisfying the coalitional inequalities of Proposition 5, so the full set of implementing information structures is characterized, not merely its existence.
Reading between the lines
- If the observed action frequencies are estimates from finite samples, the sharp inequalities become a testing problem; a natural extension is to check the inequalities with a slack proportional to sampling error, or to compute a confidence set for the implied priors.
- The affine-difference case is a generalized convex-order condition, so existing empirical tests of stochastic dominance or mean-preserving spreads could be repurposed as tests of information-rationalizability.
- Because $M(u,\nu_0)$ is a Minkowski sum, mixing observed action distributions from different populations corresponds to Minkowski combinations of the corresponding prior sets, which suggests a way to aggregate or compare information-rationalizability across heterogeneous groups.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper studies when an observed marginal distribution over actions can be rationalized as the outcome of a decision maker who observes some information before acting. For a fixed utility function u, prior μ0, and action distribution ν0, the authors define BCE-consistency via the existence of an obedient joint distribution with those marginals. Their central result, Theorem 1, characterizes the set M(u,ν0) of priors consistent with ν0 as the ν0-weighted Minkowski sum of the optimal-belief sets Δ*_u(a), and shows that membership can be checked by finitely many support-function inequalities indexed by the extreme rays of the common refinement of the normal fans of the Δ*_u(a). Theorems 2–4 provide more explicit test-function sets under small state spaces or under monotone/concave and affine- or two-step-difference utility assumptions. Section 5 derives comparative statics and cross-decision-problem consistency; Section 6 characterizes the set of posterior distributions implementing a given marginal via Gale's flow theorem; Appendix B extends the main ideas to compact Polish spaces under a first-order approach.
Significance. If the results hold, the paper makes a genuine contribution: it converts the existence question for a single-agent Bayes correlated equilibrium with observed action marginals into a finite system of inequalities, which is exactly the kind of characterization needed for empirical work that observes only average choices. The main derivations are clean and appropriately use standard tools: support functions and normal fans from convex geometry, Strassen's theorem for the continuum extension, and Gale's flow theorem for the posterior-implementation result. The paper is honest about its scope: the utility function is fixed or parameterized, and the observed action distribution is treated as exact. These limitations are stated explicitly in Remark 1 and do not undermine the mathematical claims. The paper does not rely on fitted parameters or self-citations, and the finite inequality tests are, in principle, falsifiable.
minor comments (6)
- [Definition 6 and Theorem 4] The notation for the two values of d(aj+1,aj,·) is hard to parse: the manuscript writes 'dj+1,j < 0 < dj+1,j', which uses the same symbol for both values, and the formula for q↑_j then becomes ambiguous. Please introduce distinct notation such as \underline{d}_{j+1,j} and \overline{d}_{j+1,j} throughout the statement and proof.
- [Theorem 4 statement] The sentence 'The (µ0,ν0) ∈ ∆(Ω) × ∆(A) is BCE-consistent given u' contains a grammatical error; it should read 'The pair (µ0,ν0) ∈ ∆(Ω) × ∆(A) is BCE-consistent given u.'
- [Appendix A.2, proof of Lemma 1] The assertion that the dual minimizer p is single-peaked is stated without proof. It follows from the fact that each term is monotone in the state and p is the minimum of an increasing and a decreasing family, but spelling this out in one sentence would make the proof more transparent.
- [Appendix B] The notation 'U SC(A)' appears with an unwanted space; it should be 'USC(A)' for the space of upper-semicontinuous functions.
- [Corollary 2] The sentence 'Whenever a1 is optimal at the prior, the right-hand side of Equation 10 is 0' is imprecise: Equation 10 defines the lower bound LB, so the sentence should read 'the lower bound LB(µ0,d) equals 0'; the analogous comment applies to Equation 11 and the upper bound.
- [Section 3, discussion after Equation (4)] The proof of Theorem 2 in Appendix A.1 is concise, especially the d=2 case. A short expansion of why every facet normal of M(u,ν0) must already be a facet normal of some Δ*_u(a) in R^2, rather than a new direction created by the intersection of vertex cones, would help the reader see why |Ω|≤3 is the critical threshold.
Circularity Check
No significant circularity: the central characterization is a direct derivation from stated primitives against external mathematical results.
full rationale
The paper's core claim, Theorem 1, is derived from the Minkowski-sum representation M(u,ν0)=Σ_a ν0(a)Δ*_u(a), which is an immediate rewriting of Definition 1 in terms of conditional beliefs: Bayes plausibility plus obedience exactly say that the prior is a ν0-weighted average of beliefs in the Δ*_u(a) sets, and conversely any such weighted average yields a feasible joint distribution. This is an equivalence by construction of the definitions, not a circular reduction of a prediction to a fitted input. The subsequent support-function characterization uses the standard external fact that the normal fan of a Minkowski sum is the common refinement of the summands' normal fans (Ziegler 2012), and the test-function refinements in Theorems 2-4 are proved in Appendix A.2 through dual linear programs and inductions; no fitted parameter is renamed as a prediction and no benchmark is reverse-engineered. Proposition 5 is derived from Gale's (1957) flow theorem, and the first-order-approach extension in Appendix B relies on Strassen (1965) and Kolotilin et al. (2025), all external. The paper's stated limitations—that the utility function u is known and that the observed action distribution ν0 is treated as exact—are explicit modeling assumptions, not hidden equivalences. There are no self-citations used to justify a load-bearing uniqueness claim or to smuggle in an ansatz. Accordingly, the paper is self-contained against external benchmarks and merits a circularity score of 0.
Assumptions & free parameters
assumptions (7)
- domain assumption The DM's behavior is captured by a Bayes correlated equilibrium: there exists a joint distribution π over actions and states with marginals μ0 and ν0 satisfying obedience constraints (Definition 1).
- domain assumption The analyst knows the DM's utility function u; only the prior and the information structure are unknown (Remark 1).
- domain assumption Finite state and action spaces in the main text; compact Polish spaces in Appendix B under the first-order approach.
- domain assumption No action in the support of ν0 is strictly dominated, and every nonempty Δ*_u(a) is full-dimensional, with the general case handled in Appendix A.1.
- ad hoc to paper Assumption 1: utility has increasing differences and concavity*, meaning at most two optimal adjacent actions at any belief, used for Lemma 1 and Theorems 3 and 4.
- domain assumption Affine utility differences (Definition 5) or two-step utility differences (Definition 6) for the closed-form systems in Theorems 3 and 4.
- standard math Standard convex geometry: support functions of Minkowski sums, normal fans, common refinements, and facet-defining halfspaces, plus Strassen's theorem and Gale's flow theorem.
Cite this review
Pith. "Pith review of Revealed Information." pith.science (2026). https://pith.science/paper/HODXP7KV
@misc{pith2026241113293,
author = {Pith},
title = {Pith review of: Revealed Information},
year = {2026},
howpublished = {\url{https://pith.science/paper/HODXP7KV}},
note = {Machine review of arXiv:2411.13293}
}
read the original abstract
An analyst observes the frequency with which a decision maker (DM) takes actions, but not the frequency conditional on payoff-relevant states. We ask when the analyst can rationalize the DM's choices as if the DM first learns something about the state before acting. We provide a support-function characterization of the triples of utility functions, prior beliefs, and (marginal) distributions over actions such that the DM's action distribution is consistent with information given the DM's prior and utility function. Assumptions on the cardinality of the state space and the utility function allow us to refine this characterization, obtaining a sharp system of finitely many inequalities the utility function, prior, and action distribution must satisfy. We apply our characterization to study comparative statics and to identify conditions under which a single information structure rationalizes choices across multiple decision problems. We characterize the set of distributions over posterior beliefs that are consistent with the DM's choices. We extend our results to settings with a continuum of actions and states assuming the first-order approach applies, and to simple multi-agent settings.
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Works this paper leans on
-
[1]
Aliprantis, C. D. and K. C. Border (2013): Infinite Dimensional Analysis: A Hitchhiker's Guide, Springer-Verlag Berlin and Heidelberg GmbH & Company KG
work page 2013
-
[2]
Arieli, I. and Y. Babichenko (2019): Private bayesian persuasion, Journal of Economic Theory, 182, 185--217
work page 2019
-
[3]
Arieli, I., Y. Babichenko, F. Sandomirskiy, and O. Tamuz (2021): Feasible joint posterior beliefs, Journal of Political Economy, 129, 2546--2594
work page 2021
-
[4]
Azrieli, Y. and J. Rehbeck (2022): Marginal stochastic choice, arXiv preprint arXiv:2208.08492
work page Pith review arXiv 2022
-
[5]
Barseghyan, L., F. Molinari, T. O'Donoghue, and J. C. Teitelbaum (2013): The nature of risk preferences: Evidence from insurance choices, American economic review, 103, 2499--2529
work page 2013
-
[6]
Barseghyan, L., J. Prince, and J. C. Teitelbaum (2011): Are risk preferences stable across contexts? Evidence from insurance data, American Economic Review, 101, 591--631
work page 2011
-
[7]
Beresteanu, A., I. Molchanov, and F. Molinari (2011): Sharp identification regions in models with convex moment predictions, Econometrica, 79, 1785--1821
work page 2011
-
[8]
Bergemann, D., B. Brooks, and S. Morris (2015): The limits of price discrimination, American Economic Review, 105, 921--957
work page 2015
Show all 51 references
-
[9]
--- -.1pt --- -.1pt --- (2022): Counterfactuals with Latent Information, American Economic Review, 112, 343--368
2022
-
[10]
Bergemann, D. and S. Morris (2016): Bayes correlated equilibrium and the comparison of information structures in games, Theoretical Economics, 11, 487--522
2016
-
[11]
Border, K. C. (1991): Functional analytic tools for expected utility theory, in Positive Operators, Riesz Spaces, and Economics, ed. by C. D. Aliprantis, K. C. Border, and W. A. Luxemburg, Springer, 69--88
1991
-
[12]
Caplin, A. and M. Dean (2015): Revealed preference, rational inattention, and costly information acquisition, American Economic Review, 105, 2183--2203
2015
-
[13]
Dean, and J
Caplin, A., M. Dean, and J. Leahy (2022): Rationally inattentive behavior: Characterizing and generalizing Shannon entropy, Journal of Political Economy, 130, 1676--1715
2022
-
[14]
Caplin, A., D. J. Martin, and P. Marx (2023): Rationalizable Learning, Tech. rep., National Bureau of Economic Research
2023
-
[15]
Chambers, C. P., C. Liu, and J. Rehbeck (2020): Costly information acquisition, Journal of Economic Theory, 186, 104979
2020
-
[16]
Cohen, A. and L. Einav (2007): Estimating risk preferences from deductible choice, American economic review, 97, 745--788
2007
-
[17]
Das, S., S. R. Dev, and S. Sarvottamananda (2024): A worst-case optimal algorithm to compute the Minkowski sum of convex polytopes, Discrete Applied Mathematics, 350, 44--61
2024
-
[18]
De Oliveira, H. and R. Lamba (2022): Rationalizing dynamic choices, Available at SSRN 3332092
2022
-
[19]
(2022): Posterior separable cost of information, American Economic Review, 112, 3215--3259
Denti, T. (2022): Posterior separable cost of information, American Economic Review, 112, 3215--3259
2022
-
[20]
Dewan, A. and N. Neligh (2020): Estimating information cost functions in models of rational inattention, Journal of Economic Theory, 187, 105011
2020
-
[21]
Dickstein, M. J., J. Jeon, and E. Morales (2024): Patient costs and physicians' information, Tech. rep., National Bureau of Economic Research
2024
-
[22]
Dickstein, M. J. and E. Morales (2018): What do exporters know? The Quarterly Journal of Economics, 133, 1753--1801
2018
-
[23]
Dillenberger, D., R. V. Krishna, and P. Sadowski (2023): Subjective information choice processes, Theoretical Economics, 18, 529--559
2023
-
[24]
Dillenberger, D., J. S. Lleras, P. Sadowski, and N. Takeoka (2014): A theory of subjective learning, Journal of Economic Theory, 153, 287--312
2014
-
[25]
Enke, B. and T. Graeber (2023): Cognitive uncertainty, The Quarterly Journal of Economics, 138, 2021--2067
2023
-
[26]
Ergin, H. and T. Sarver (2010): A unique costly contemplation representation, Econometrica, 78, 1285--1339
2010
-
[27]
(1957): A theorem on flows in networks, Pacific J
Gale, D. (1957): A theorem on flows in networks, Pacific J. Math, 7, 1073--1082
1957
-
[28]
Galichon, A. and M. Henry (2011): Set identification in models with multiple equilibria, The Review of Economic Studies, 78, 1264--1298
2011
-
[29]
Gualdani, C. and S. Sinha (2024): Identification in discrete choice models with imperfect information, Journal of Econometrics, 244, 105854
2024
-
[30]
Kamenica, E. and M. Gentzkow (2011): Bayesian persuasion, American Economic Review, 101, 2590--2615
2011
-
[31]
Khaw, M. W., Z. Li, and M. Woodford (2021): Cognitive imprecision and small-stakes risk aversion, The Review of Economic Studies, 88, 1979--2013
2021
-
[32]
(2015): Identifying higher-order rationality, Econometrica, 83, 2065--2079
Kneeland, T. (2015): Identifying higher-order rationality, Econometrica, 83, 2065--2079
2015
-
[33]
(2018): Optimal information disclosure: A linear programming approach, Theoretical Economics, 13, 607--635
Kolotilin, A. (2018): Optimal information disclosure: A linear programming approach, Theoretical Economics, 13, 607--635
2018
-
[34]
Corrao, and A
Kolotilin, A., R. Corrao, and A. Wolitzky (2025): Persuasion and matching: Optimal productive transport, 133
2025
-
[35]
Kolotilin, A. and A. Wolitzky (2024): Distributions of Posterior Quantiles via Matching, Theoretical Economics, 19, 1399--1413
2024
-
[36]
(2016): Random choice and private information, Econometrica, 84, 1983--2027
Lu, J. (2016): Random choice and private information, Econometrica, 84, 1983--2027
2016
-
[37]
Magnolfi, L. and C. Roncoroni (2023): Estimation of discrete games with weak assumptions on information, The Review of Economic Studies, 90, 2006--2041
2023
-
[38]
Molchanov, I. and F. Molinari (2018): Random sets in econometrics, vol. 60, Cambridge University Press
2018
-
[39]
Morris, S. E. (2020): No trade and feasible joint posterior beliefs, Tech. rep., Massachusetts Institute of Technology
2020
-
[40]
Myerson, R. B. (1982): Optimal coordination mechanisms in generalized principal--agent problems, Journal of Mathematical Economics, 10, 67--81
1982
-
[41]
(2024): Identifying prediction mistakes in observational data, The Quarterly Journal of Economics, 139, 1665--1711
Rambachan, A. (2024): Identifying prediction mistakes in observational data, The Quarterly Journal of Economics, 139, 1665--1711
2024
-
[42]
(2023): Revealed Bayesian expected utility with limited data, Journal of Economic Behavior & Organization, 207, 81--95
Rehbeck, J. (2023): Revealed Bayesian expected utility with limited data, Journal of Economic Behavior & Organization, 207, 81--95
2023
-
[43]
Rockafellar, R. T. (1970): Convex Analysis, Convex Analysis, 28
1970
-
[44]
(1982): Convergence of Lebesgue integrals with varying measures, Sankhy \=a : The Indian Journal of Statistics, Series A , 380--402
Serfozo, R. (1982): Convergence of Lebesgue integrals with varying measures, Sankhy \=a : The Indian Journal of Statistics, Series A , 380--402
1982
-
[45]
Strack, P. and K. H. Yang (2024): Privacy Preserving Signals, Available at SSRN 4467608
2024
-
[46]
(1965): The existence of probability measures with given marginals, The Annals of Mathematical Statistics, 36, 423--439
Strassen, V. (1965): The existence of probability measures with given marginals, The Annals of Mathematical Statistics, 36, 423--439
1965
-
[47]
Tamer, and J
Syrgkanis, V., E. Tamer, and J. Ziani (2017): Inference on auctions with weak assumptions on information, arXiv preprint arXiv:1710.03830
2017 arXiv
-
[48]
Toikka, and R
Vohra, A., J. Toikka, and R. Vohra (2023): Bayesian persuasion: Reduced form approach, Journal of Mathematical Economics, 102863
2023
-
[49]
(2007): Minkowski sums of polytopes: combinatorics and computation, Tech
Weibel, C. (2007): Minkowski sums of polytopes: combinatorics and computation, Tech. rep., EPFL
2007
-
[50]
Yang, K. H. and A. K. Zentefis (2024): Monotone function intervals: Theory and applications, American Economic Review, 114, 2239--2270
2024
-
[51]
Ziegler, G. M. (2012): Lectures on polytopes, vol. 152, Springer Science & Business Media
2012
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