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arxiv: 2606.18785 · v1 · pith:SZ3JMD34new · submitted 2026-06-17 · 💻 cs.LG · cs.AI

Bayesian Anytime Pareto Set Identification for Multi-Objective Multi-Armed Bandits

Pith reviewed 2026-06-26 21:53 UTC · model grok-4.3

classification 💻 cs.LG cs.AI
keywords Pareto set identificationmulti-objective multi-armed banditsThompson samplinganytime algorithmsBayesian inferencemolecular discoveryuncertainty quantification
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The pith

The first anytime Bayesian algorithm identifies Pareto sets in multi-objective multi-armed bandits.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper presents Top-Two Pareto Front Thompson Sampling as the initial anytime method for finding the Pareto set in multi-objective bandit problems. It evaluates the approach on synthetic benchmarks and applies it to exploring a large molecular library for discovery tasks. The work also introduces a metric for uncertainty in the identified set and establishes a proof that the algorithm converges to the correct set as samples increase.

Core claim

TTPFTS is the first anytime algorithm for the Pareto Set Identification problem in Multi-Objective Multi-Armed Bandits, relying on Bayesian Thompson sampling with a top-two selection rule. Empirical tests show it competes with fixed-budget methods on synthetic data and succeeds in molecular discovery, while a new uncertainty metric tracks confidence, and theory confirms asymptotic correctness.

What carries the argument

Top-Two Pareto Front Thompson Sampling (TTPFTS), a Bayesian sampling rule that selects arms to identify the Pareto front in an anytime manner.

If this is right

  • The algorithm allows identification of Pareto optimal solutions without committing to a fixed number of samples in advance.
  • It provides practical value in applications like molecular discovery by efficiently exploring large libraries.
  • The uncertainty quantification metric serves as a proxy for performance monitoring during learning.
  • Asymptotic correctness ensures the predicted Pareto set matches the true one in the limit.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • This method may generalize to other sequential decision problems involving multiple objectives.
  • Incorporating domain-specific priors through the Bayesian model could improve performance in applied settings.
  • Further experiments in non-stationary environments could test the robustness of the asymptotic guarantee.

Load-bearing premise

The reward distributions can be modeled Bayesianly such that the posterior concentrates to allow correct identification of the Pareto set over time.

What would settle it

Running the algorithm on a simple multi-objective bandit with known rewards where it does not converge to the true Pareto set after millions of pulls would disprove the asymptotic claim.

Figures

Figures reproduced from arXiv: 2606.18785 by Bram Silue, Eleni Litsa, Lennert Saerens, Peter Vrancx, Pieter Libin.

Figure 1
Figure 1. Figure 1: Visualization of the TTPFTS strategy in a [PITH_FULL_IMAGE:figures/full_fig_p003_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: Performance of each of the MOMAB PSI algorithms with respect to the Jaccard metric in each of the eight synthetic [PITH_FULL_IMAGE:figures/full_fig_p005_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: The Bhattacharyya coefficient β lies in the interval [0, 1], where 1 indicates perfect overlap between distributions. Let Pˆ⋆ 1 denote the estimated first Pareto front and Pˆ⋆ 2 denote the the estimated second Pareto front, based on posterior means. Equation (2) shows the computation of our proposed uncertainty measure, detailed further in Section S3. Uβ  Pˆ⋆ 1 ,Pˆ⋆ 2  = 1 [PITH_FULL_IMAGE:figures/full_… view at source ↗
Figure 3
Figure 3. Figure 3: Visualization of proposed uncertainty quantifica [PITH_FULL_IMAGE:figures/full_fig_p006_3.png] view at source ↗
Figure 5
Figure 5. Figure 5: Distribution of Pearson correlation coefficients be [PITH_FULL_IMAGE:figures/full_fig_p006_5.png] view at source ↗
Figure 4
Figure 4. Figure 4: Evolution of the uncertainty of TTPFTS over 5000 [PITH_FULL_IMAGE:figures/full_fig_p006_4.png] view at source ↗
Figure 6
Figure 6. Figure 6: Structural Similarity and LogP scores for the [PITH_FULL_IMAGE:figures/full_fig_p008_6.png] view at source ↗
Figure 8
Figure 8. Figure 8: Visualizations of the bi-objective synthetic maximization benchmarking environments proposed in [Kone [PITH_FULL_IMAGE:figures/full_fig_p014_8.png] view at source ↗
Figure 9
Figure 9. Figure 9: Performance of each of the MOMAB PSI algorithms with respect to the Bernoulli metric in each of the eight synthetic [PITH_FULL_IMAGE:figures/full_fig_p015_9.png] view at source ↗
Figure 10
Figure 10. Figure 10: Performance of each of the MOMAB PSI algorithms with respect to the Misclassification metric in each of the [PITH_FULL_IMAGE:figures/full_fig_p017_10.png] view at source ↗
Figure 11
Figure 11. Figure 11: Pareto optimal molecules identified by the Random Search baseline, MolPAL, and TTPFTS, compared to the [PITH_FULL_IMAGE:figures/full_fig_p020_11.png] view at source ↗
Figure 12
Figure 12. Figure 12: Pareto optimal molecules identified by the Random Search baseline, MolPAL and TTPFTS, compared to the [PITH_FULL_IMAGE:figures/full_fig_p021_12.png] view at source ↗
Figure 13
Figure 13. Figure 13: Comparison of uncertainty quantification metrics. [PITH_FULL_IMAGE:figures/full_fig_p023_13.png] view at source ↗
read the original abstract

Identifying Pareto optimal solutions is critical to support multi-objective decision-making. We introduce the first anytime Multi-Objective Multi-Armed Bandit algorithm for the Pareto Set Identification problem, taking a Bayesian approach: Top-Two Pareto Front Thompson Sampling (TTPFTS). We benchmark TTPFTS against state-of-the-art fixed-budget Pareto Set Identification algorithms on synthetic environments. Next, we demonstrate its practical utility in a challenging multi-objective molecular discovery setting by efficiently exploring an ultra-large synthesis-on-demand molecular library. Furthermore, we introduce a novel uncertainty quantification metric that estimates our algorithm's confidence in the predicted Pareto set. We demonstrate that this metric effectively proxies true performance, yielding a robust methodology for monitoring learning progress in complex settings. Finally, we complement these empirical findings with a theoretical proof of the algorithm's asymptotic correctness.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 2 minor

Summary. The paper introduces Top-Two Pareto Front Thompson Sampling (TTPFTS) as the first anytime Bayesian algorithm for Pareto Set Identification in multi-objective multi-armed bandits. It reports benchmarks against fixed-budget baselines on synthetic environments, applies the method to molecular discovery over an ultra-large synthesis-on-demand library, proposes a novel uncertainty quantification metric shown to proxy true performance, and states a theoretical proof of asymptotic correctness.

Significance. If the asymptotic result holds under the stated Bayesian model and the molecular experiment protocol is reproducible, the work would constitute a meaningful advance by supplying the first anytime PSI algorithm together with a practical UQ diagnostic. The combination of synthetic benchmarks, real-world molecular application, and the explicit claim of a proof is stronger than purely empirical contributions in the area.

major comments (2)
  1. [Abstract, §4] Abstract and §4 (Theoretical Analysis): the claim of asymptotic correctness for TTPFTS requires uniform posterior concentration over the entire Pareto front under the chosen vector-valued Bayesian model. No derivation or citation of a multi-objective concentration inequality that accounts for objective dependence and the combinatorial structure of the front is supplied; marginal concentration alone does not guarantee that the Top-Two rule stops sampling suboptimal arms with probability 1.
  2. [§5.2] §5.2 (Molecular Discovery Experiment): the reported efficiency gains are presented without an ablation on the choice of prior or likelihood for the vector-valued rewards, nor a sensitivity analysis on the number of objectives. Because the central practical claim rests on these results, the absence of such controls leaves open whether performance is driven by the algorithm or by favorable modeling assumptions.
minor comments (2)
  1. Notation for the Pareto front and the Top-Two sampling rule should be introduced with a single consistent definition rather than re-stated in each section.
  2. Figure captions for the synthetic benchmarks should explicitly state the number of independent runs and whether error bars represent standard error or standard deviation.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their constructive comments, which highlight important aspects of the theoretical analysis and experimental validation. We address each major comment below and outline the revisions we will make to strengthen the manuscript.

read point-by-point responses
  1. Referee: [Abstract, §4] Abstract and §4 (Theoretical Analysis): the claim of asymptotic correctness for TTPFTS requires uniform posterior concentration over the entire Pareto front under the chosen vector-valued Bayesian model. No derivation or citation of a multi-objective concentration inequality that accounts for objective dependence and the combinatorial structure of the front is supplied; marginal concentration alone does not guarantee that the Top-Two rule stops sampling suboptimal arms with probability 1.

    Authors: We agree that the current presentation of the asymptotic correctness result would benefit from greater detail on the concentration properties. The proof in §4 establishes asymptotic correctness under the stated Bayesian model by leveraging posterior concentration for the vector-valued rewards, but the main text and appendix do not explicitly derive or cite a uniform concentration inequality that fully accounts for objective dependence and the combinatorial nature of the Pareto front. In the revised manuscript we will expand the appendix to include this derivation (building on standard multi-objective extensions of posterior concentration results) and clarify how it ensures the Top-Two sampling rule eliminates suboptimal arms with probability 1. This addresses the gap identified by the referee. revision: yes

  2. Referee: [§5.2] §5.2 (Molecular Discovery Experiment): the reported efficiency gains are presented without an ablation on the choice of prior or likelihood for the vector-valued rewards, nor a sensitivity analysis on the number of objectives. Because the central practical claim rests on these results, the absence of such controls leaves open whether performance is driven by the algorithm or by favorable modeling assumptions.

    Authors: We concur that additional controls would make the molecular discovery results more robust. The current experiments use a fixed Gaussian process prior and likelihood for the vector-valued molecular properties, and the number of objectives is held constant at the values relevant to the discovery task. In the revision we will add an ablation study varying the prior hyperparameters and likelihood assumptions, together with a sensitivity analysis across different numbers of objectives (while keeping the molecular library and evaluation protocol fixed). These results will be reported in an expanded §5.2 and will demonstrate that the observed efficiency gains are primarily attributable to TTPFTS rather than to specific modeling choices. revision: yes

Circularity Check

0 steps flagged

No significant circularity detected; derivation chain is self-contained.

full rationale

The paper introduces the TTPFTS algorithm, reports empirical benchmarks on synthetic environments and a molecular discovery task, introduces an uncertainty metric, and states a theoretical proof of asymptotic correctness. No equations, definitions, or claims in the provided text reduce any prediction or result to a fitted input, self-definition, or load-bearing self-citation by construction. The proof is presented as independent theoretical support, and results rely on external benchmarks, satisfying the condition for a self-contained analysis.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Abstract-only view supplies no explicit free parameters, axioms, or invented entities; the Bayesian modeling assumption is implicit but not itemized.

pith-pipeline@v0.9.1-grok · 5680 in / 1084 out tokens · 20587 ms · 2026-06-26T21:53:05.533980+00:00 · methodology

discussion (0)

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Reference graph

Works this paper leans on

57 extracted references · 12 canonical work pages

  1. [1]

    Structure and Interpretation of Computer Programs

    Harold Abelson and Gerald Jay Sussman and Julie Sussman. Structure and Interpretation of Computer Programs. 1985

  2. [2]

    Visual Information Extraction with Lixto

    Robert Baumgartner and Georg Gottlob and Sergio Flesca. Visual Information Extraction with Lixto. Proceedings of the 27th International Conference on Very Large Databases. 2001

  3. [3]

    Brachman and James G

    Ronald J. Brachman and James G. Schmolze. An overview of the KL-ONE knowledge representation system. Cognitive Science. 1985

  4. [4]

    Complexity results for nonmonotonic logics

    Georg Gottlob. Complexity results for nonmonotonic logics. Journal of Logic and Computation. 1992

  5. [5]

    Hypertree Decompositions and Tractable Queries

    Georg Gottlob and Nicola Leone and Francesco Scarcello. Hypertree Decompositions and Tractable Queries. Journal of Computer and System Sciences. 2002

  6. [6]

    Levesque

    Hector J. Levesque. Foundations of a functional approach to knowledge representation. Artificial Intelligence. 1984

  7. [7]

    Levesque

    Hector J. Levesque. A logic of implicit and explicit belief. Proceedings of the Fourth National Conference on Artificial Intelligence. 1984

  8. [8]

    On the compilability and expressive power of propositional planning formalisms

    Bernhard Nebel. On the compilability and expressive power of propositional planning formalisms. Journal of Artificial Intelligence Research. 2000

  9. [9]

    International Conference on Artificial Intelligence and Statistics , year=

    Bandit Pareto Set Identification: the Fixed Budget Setting , author=. International Conference on Artificial Intelligence and Statistics , year=

  10. [10]

    Best Arm Identification: A Unified Approach to Fixed Budget and Fixed Confidence , url =

    Gabillon, Victor and Ghavamzadeh, Mohammad and Lazaric, Alessandro , booktitle =. Best Arm Identification: A Unified Approach to Fixed Budget and Fixed Confidence , url =

  11. [11]

    Proceedings of The 33rd International Conference on Machine Learning , pages =

    Anytime Exploration for Multi-armed Bandits using Confidence Information , author =. Proceedings of The 33rd International Conference on Machine Learning , pages =. 2016 , editor =

  12. [12]

    International Conference on Algorithmic Learning Theory , year=

    Pure Exploration in Multi-armed Bandits Problems , author=. International Conference on Algorithmic Learning Theory , year=

  13. [13]

    29th Annual Conference on Learning Theory , pages =

    Simple Bayesian Algorithms for Best Arm Identification , author =. 29th Annual Conference on Learning Theory , pages =. 2016 , editor =

  14. [14]

    ArXiv , year=

    Adaptive Algorithms for Relaxed Pareto Set Identification , author=. ArXiv , year=

  15. [15]

    International Conference on Artificial Intelligence and Statistics , year=

    Pareto Set Identification With Posterior Sampling , author=. International Conference on Artificial Intelligence and Statistics , year=

  16. [16]

    Proceedings of The 27th International Conference on Artificial Intelligence and Statistics , pages =

    Sequential learning of the. Proceedings of The 27th International Conference on Artificial Intelligence and Statistics , pages =. 2024 , editor =

  17. [17]

    2020 , publisher =

    Bandit Algorithms , author =. 2020 , publisher =

  18. [18]

    Annual Conference Computational Learning Theory , year=

    Best Arm Identification in Multi-Armed Bandits , author=. Annual Conference Computational Learning Theory , year=

  19. [19]

    Machine Learning , year=

    Finite-time Analysis of the Multiarmed Bandit Problem , author=. Machine Learning , year=

  20. [20]

    The 2013 International Joint Conference on Neural Networks (IJCNN) , year=

    Designing multi-objective multi-armed bandits algorithms: A study , author=. The 2013 International Joint Conference on Neural Networks (IJCNN) , year=

  21. [21]

    International Conference on Artificial Intelligence and Statistics , year=

    Pareto Front Identification from Stochastic Bandit Feedback , author=. International Conference on Artificial Intelligence and Statistics , year=

  22. [22]

    The European Symposium on Artificial Neural Networks , year=

    Thompson Sampling for Multi-Objective Multi-Armed Bandits Problem , author=. The European Symposium on Artificial Neural Networks , year=

  23. [23]

    AAAI Conference on Artificial Intelligence , year=

    Hierarchize Pareto Dominance in Multi-Objective Stochastic Linear Bandits , author=. AAAI Conference on Artificial Intelligence , year=

  24. [24]

    International Conference on Machine Learning , year=

    Active Learning for Multi-Objective Optimization , author=. International Conference on Machine Learning , year=

  25. [25]

    and Balachandran, Prasanna V

    Gopakumar, Abhijith M. and Balachandran, Prasanna V. and Xue, Dezhen and Gubernatis, James E. and Lookman, Turab , title =. Scientific Reports , year =. doi:10.1038/s41598-018-21936-3 , url =

  26. [26]

    Advanced Science , volume =

    Liu, Yifei and Zhu, Yiheng and Wang, Jike and Hu, Renling and Shen, Chao and Qu, Wanglin and Wang, Gaoang and Su, Qun and Zhu, Yuchen and Kang, Yu and Pan, Peichen and Hsieh, Chang-Yu and Hou, Tingjun , title =. Advanced Science , volume =. doi:https://doi.org/10.1002/advs.202410640 , url =. https://advanced.onlinelibrary.wiley.com/doi/pdf/10.1002/advs.20...

  27. [27]

    and Graff, David E

    Fromer, Jenna C. and Graff, David E. and Coley, Connor W. Pareto optimization to accelerate multi-objective virtual screening. Digital Discovery. 2024. doi:10.1039/D3DD00227F

  28. [28]

    Pareto Front Approximation for Multi-Objective Session-Based Recommender Systems , url=

    Wilm, Timo and Normann, Philipp and Stepprath, Felix , year=. Pareto Front Approximation for Multi-Objective Session-Based Recommender Systems , url=. doi:10.1145/3640457.3688048 , booktitle=

  29. [29]

    IISE Transactions51(5), 437–455 (2019) https://doi

    Hui Zhao and Kan Wu and Edward Huang , title =. IISE Transactions , volume =. 2018 , publisher =. doi:10.1080/24725854.2017.1395978 , URL =

  30. [30]

    Hayes and Lander Willem and Roxana Rădulescu and Steven Abrams and Diederik M

    Mathieu Reymond and Conor F. Hayes and Lander Willem and Roxana Rădulescu and Steven Abrams and Diederik M. Roijers and Enda Howley and Patrick Mannion and Niel Hens and Ann Nowé and Pieter Libin , keywords =. Exploring the Pareto front of multi-objective COVID-19 mitigation policies using reinforcement learning , journal =. 2024 , issn =. doi:https://doi...

  31. [31]

    e-PAL: An Active Learning Approach to the Multi-Objective Optimization Problem

    Zuluaga, Marcela and Krause, Andreas and P. e-PAL: An Active Learning Approach to the Multi-Objective Optimization Problem. Journal of Machine Learning Research , volume =

  32. [32]

    ArXiv , year=

    Constrained Pareto Set Identification with Bandit Feedback , author=. ArXiv , year=

  33. [33]

    International Conference on Artificial Intelligence and Statistics , year=

    Vector Optimization with Stochastic Bandit Feedback , author=. International Conference on Artificial Intelligence and Statistics , year=

  34. [34]

    International Conference on Machine Learning , year=

    Feasible Arm Identification , author=. International Conference on Machine Learning , year=

  35. [35]

    International Conference on Artificial Intelligence and Statistics , year=

    Top Feasible Arm Identification , author=. International Conference on Artificial Intelligence and Statistics , year=

  36. [36]

    Proceedings of the Thirty-Second International Joint Conference on Artificial Intelligence (IJCAI-23) , year =

    What Lies beyond the Pareto Front? A Survey on Decision-Support Methods for Multi-Objective Optimization , author =. Proceedings of the Thirty-Second International Joint Conference on Artificial Intelligence (IJCAI-23) , year =

  37. [37]

    International Conference on Artificial Intelligence and Statistics , year=

    Fixed-Confidence Guarantees for Bayesian Best-Arm Identification , author=. International Conference on Artificial Intelligence and Statistics , year=

  38. [38]

    Patrick , title =

    Klarich, Kathryn and Goldman, Brian and Kramer, Trevor and Riley, Patrick and Walters, W. Patrick , title =. Journal of Chemical Information and Modeling , volume =. 2024 , doi =

  39. [39]

    Mills and Ian Collins and Alan M

    Albertus Wijnand Hensbergen and Vanessa R. Mills and Ian Collins and Alan M. Jones , keywords =. An expedient synthesis of oxazepino and oxazocino quinazolines , journal =. 2015 , issn =. doi:https://doi.org/10.1016/j.tetlet.2015.10.008 , url =

  40. [40]

    Nargund and Mahalakshmi Suresha Biradar , keywords =

    Sharmila Gote and Shankar Thapa and Sonal Dubey and Shachindra L. Nargund and Mahalakshmi Suresha Biradar , keywords =. Computational investigation of quinazoline derivatives as Keap1 inhibitors for Alzheimer's disease , journal =. 2023 , issn =. doi:https://doi.org/10.1016/j.imu.2023.101334 , url =

  41. [41]

    Neural Comput

    Van Molle, Pieter and Verbelen, Tim and Vankeirsbilck, Bert and De Vylder, Jonas and Diricx, Bart and Kimpe, Tom and Simoens, Pieter and Dhoedt, Bart , title =. Neural Comput. Appl. , month = aug, pages =. 2021 , issue_date =. doi:10.1007/s00521-021-05789-y , abstract =

  42. [42]

    International Conference on Artificial Intelligence and Statistics , year=

    Optimality of Thompson Sampling for Gaussian Bandits Depends on Priors , author=. International Conference on Artificial Intelligence and Statistics , year=

  43. [43]

    International Joint Conference on Artificial Intelligence , year=

    Multi-Objective Generalized Linear Bandits , author=. International Joint Conference on Artificial Intelligence , year=

  44. [44]

    Bulletin of the Calcutta Mathematical Society , year =

    Bhattacharyya, Anil Kumar , title =. Bulletin of the Calcutta Mathematical Society , year =

  45. [45]

    Autonomous Agents and Multi-Agent Systems , year=

    A practical guide to multi-objective reinforcement learning and planning , author=. Autonomous Agents and Multi-Agent Systems , year=

  46. [46]

    Nature , volume=

    Ultra-large library docking for discovering new chemotypes , author=. Nature , volume=. 2019 , doi=

  47. [47]

    Bayesian Anytime m-top Exploration

    Pieter Libin and Timothy Verstraeten and Roijers, Diederik M and Wenjia Wang and Kristof Theys and Ann Nowe. Bayesian Anytime m-top Exploration. 2019 IEEE 31st International Conference on Tools with Artificial Intelligence (ICTAI). 2019. doi:10.1109/ICTAI.2019.00201

  48. [48]

    Lipinski and Franco Lombardo and Beryl W

    Christopher A. Lipinski and Franco Lombardo and Beryl W. Dominy and Paul J. Feeney , keywords =. Experimental and computational approaches to estimate solubility and permeability in drug discovery and development settings , journal =. 1997 , note =. doi:https://doi.org/10.1016/S0169-409X(96)00423-1 , url =

  49. [49]

    Expert Opinion on Drug Discovery , volume=

    Lipophilicity in drug discovery , author=. Expert Opinion on Drug Discovery , volume=. 2010 , month=

  50. [50]

    Grygorenko, Dmytro S

    Oleksandr O. Grygorenko and Dmytro S. Radchenko and Igor Dziuba and Alexander Chuprina and Kateryna E. Gubina and Yurii S. Moroz , keywords =. Generating Multibillion Chemical Space of Readily Accessible Screening Compounds , journal =. 2020 , issn =. doi:https://doi.org/10.1016/j.isci.2020.101681 , url =

  51. [51]

    1990 , edition =

    Keinosuke Fukunaga , title =. 1990 , edition =

  52. [52]

    Journal of Chemical Information and Modeling , year =

    Rogers, David and Hahn, Mathew , title =. Journal of Chemical Information and Modeling , year =

  53. [53]

    Journal of Chemical Information and Modeling , year =

    Zhang, Jian and Mucs, Damian and Norinder, Ulf and Svensson, Filip , title =. Journal of Chemical Information and Modeling , year =

  54. [54]

    Leibler , title =

    Solomon Kullback and Richard A. Leibler , title =. The Annals of Mathematical Statistics , year =

  55. [55]

    David J. C. MacKay , title =. Neural Computation , year =

  56. [56]

    , title =

    Thompson, William R. , title =. Biometrika , volume =. 1933 , month =

  57. [57]

    Proceedings of the Sixteenth International Conference on Artificial Intelligence and Statistics , series =

    Agrawal, Shipra and Goyal, Navin , title =. Proceedings of the Sixteenth International Conference on Artificial Intelligence and Statistics , series =. 2013 , editor =