pith. sign in

arxiv: 2502.07646 · v3 · pith:Z7TE26CEnew · submitted 2025-02-11 · 💻 cs.LG · stat.ME· stat.ML

Causal Additive Models with Unobserved Causal Paths and Backdoor Paths

Pith reviewed 2026-05-25 08:17 UTC · model grok-4.3

classification 💻 cs.LG stat.MEstat.ML
keywords causal discoverycausal additive modelshidden variablesbackdoor pathsregression residualsconditional independencesearch algorithm
0
0 comments X

The pith

Causal directions in additive models can be identified even with unobserved backdoor and causal paths under new regression conditions.

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

The paper aims to show that causal directions remain identifiable in causal additive models even when unobserved backdoor or causal paths exist between variables. This matters because many real-world causal systems involve hidden variables that block standard identification methods. The key is new characterizations of regression sets that correctly detect independence of residuals and conditional independencies among observed variables. These lead to a search algorithm proven sound and complete for recovering the causal structure.

Core claim

We establish sufficient conditions under which causal directions can be identified in many such cases. These conditions rely on new characterizations of regression sets to determine independence among regression residuals and conditional independencies among observed variables. Building on these results, we introduce a search algorithm that incorporates these innovations and prove its soundness and completeness.

What carries the argument

New characterizations of regression sets that determine independence among regression residuals and conditional independencies among observed variables, even with unobserved paths.

If this is right

  • Many previously unidentifiable causal relationships become identifiable under the stated conditions.
  • A search algorithm exists that is sound and complete for recovering the structure.
  • The method applies to both unobserved backdoor paths and unobserved causal paths.
  • Empirical performance is competitive with state-of-the-art causal discovery methods.

Where Pith is reading between the lines

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

  • The regression characterizations might extend to non-additive causal models if similar independence properties can be established.
  • Practical use could improve structure learning in domains with latent variables such as gene regulatory networks.
  • One could validate the conditions by generating data with controlled hidden paths and measuring how often residual independence matches the predictions.

Load-bearing premise

The new characterizations of regression sets correctly determine independence among regression residuals and conditional independencies among observed variables even when unobserved backdoor or causal paths exist.

What would settle it

A dataset generated from a known causal additive model with an unobserved path where the claimed residual independence fails to hold, causing the search algorithm to output an incorrect or incomplete causal structure.

Figures

Figures reproduced from arXiv: 2502.07646 by Shohei Shimizu, Takashi Nicholas Maeda, Thong Pham.

Figure 1
Figure 1. Figure 1: Examples of identifying causal relationships in [PITH_FULL_IMAGE:figures/full_fig_p003_1.png] view at source ↗
Figure 3
Figure 3. Figure 3: Performance in BA random graphs with Gaussian [PITH_FULL_IMAGE:figures/full_fig_p008_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: Results on sociology data. a: ground truth based on domain knowledge [Duncan et al., 1972]. A bidirected edge indicates that the relation is not modeled. A dashed directed edge represents an ancestor relationship. b: re￾sult by CAM-UV. A solid directed edge denotes a visi￾ble parent–child relationship (adjacency). An empty edge denotes a visible non-edge (non-adjacency). A bidirected edge denotes an invisi… view at source ↗
read the original abstract

Causal additive models provide a tractable yet expressive framework for causal discovery in the presence of hidden variables. When unobserved backdoor or causal paths exist between two variables, their causal relationship is often unidentifiable under existing theories. We establish sufficient conditions under which causal directions can be identified in many such cases. These conditions rely on new characterizations of regression sets to determine independence among regression residuals and conditional independencies among observed variables. Building on these results, we introduce a search algorithm that incorporates these innovations and prove its soundness and completeness. Empirical evaluations demonstrate its competitive performance against state-of-the-art methods.

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

1 major / 1 minor

Summary. The manuscript claims to establish sufficient conditions for identifying causal directions in causal additive models even when unobserved backdoor or causal paths exist between variables. These conditions rely on new characterizations of regression sets to determine independence among regression residuals and conditional independencies among observed variables. It introduces a search algorithm incorporating these results, proves its soundness and completeness, and shows competitive empirical performance against state-of-the-art methods.

Significance. If the characterizations hold, the work would meaningfully extend causal discovery to graphs with hidden paths that prior theories leave unidentifiable. The manuscript ships explicit soundness and completeness proofs for the algorithm, which is a clear strength, along with an empirical evaluation.

major comments (1)
  1. [Abstract] Abstract: The claim that the new characterizations of regression sets correctly determine independence among regression residuals and conditional independencies among observed variables even when unobserved backdoor or causal paths exist is the sole basis for the sufficient conditions and for the soundness/completeness proof of the search algorithm. The abstract supplies no counter-example checks or proof sketches, leaving this load-bearing step unverified.
minor comments (1)
  1. The abstract could include a short illustrative example of a regression set characterization to help readers assess the scope of the new conditions.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for their thoughtful review and for identifying the central role of the regression-set characterizations. We address the major comment below and propose a targeted revision to the abstract.

read point-by-point responses
  1. Referee: [Abstract] Abstract: The claim that the new characterizations of regression sets correctly determine independence among regression residuals and conditional independencies among observed variables even when unobserved backdoor or causal paths exist is the sole basis for the sufficient conditions and for the soundness/completeness proof of the search algorithm. The abstract supplies no counter-example checks or proof sketches, leaving this load-bearing step unverified.

    Authors: We agree that the abstract, as a concise summary, does not itself contain proof sketches or counter-example verification; those appear in the body of the manuscript. Section 3 derives the new regression-set characterizations, proves that they correctly identify residual independence and the relevant conditional independencies even in the presence of unobserved backdoor and causal paths, and supplies the supporting lemmas. Section 4 then uses these results to establish soundness and completeness of the search algorithm. While we believe the current abstract accurately reflects the paper’s contributions, we acknowledge that a brief additional clause could make the load-bearing step more visible to readers who stop at the abstract. We will therefore revise the abstract to include one sentence noting that the characterizations are formally proven in Section 3 and that they extend existing additive-model theory to graphs containing hidden paths. revision: yes

Circularity Check

0 steps flagged

No circularity: new characterizations and algorithm are independently derived

full rationale

The paper introduces novel characterizations of regression sets for determining residual independence and conditional independencies under hidden paths, then uses them to establish sufficient conditions for causal direction identification and to prove soundness/completeness of a new search algorithm. These steps are presented as original contributions rather than reductions to prior fits, self-citations, or definitional equivalences. No quoted equations or claims in the provided text show a result being equivalent to its inputs by construction, and the central claims retain independent mathematical content beyond any referenced prior CAM literature.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

Abstract provides no explicit free parameters, axioms, or invented entities; the work rests on the standard assumptions of causal additive models and the validity of the new regression characterizations.

axioms (1)
  • domain assumption Causal additive model framework with additive noise
    The paper builds directly on causal additive models as the base framework for handling hidden variables.

pith-pipeline@v0.9.0 · 5627 in / 1228 out tokens · 32316 ms · 2026-05-25T08:17:11.868027+00:00 · methodology

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Lean theorems connected to this paper

Citations machine-checked in the Pith Canon. Every link opens the source theorem in the public Lean library.

What do these tags mean?
matches
The paper's claim is directly supported by a theorem in the formal canon.
supports
The theorem supports part of the paper's argument, but the paper may add assumptions or extra steps.
extends
The paper goes beyond the formal theorem; the theorem is a base layer rather than the whole result.
uses
The paper appears to rely on the theorem as machinery.
contradicts
The paper's claim conflicts with a theorem or certificate in the canon.
unclear
Pith found a possible connection, but the passage is too broad, indirect, or ambiguous to say the theorem truly supports the claim.

Reference graph

Works this paper leans on

39 extracted references · 39 canonical work pages · 1 internal anchor

  1. [1]

    Adams, N

    J. Adams, N. Hansen, and K. Zhang. Identification of partially observed linear causal models: Graphical conditions for the non-gaussian and heterogeneous cases. In M. Ranzato, A. Beygelzimer, Y. Dauphin, P. Liang, and J. W. Vaughan, editors, Advances in Neural Information Processing Systems, volume 34, pages 22822--22833. Curran Associates, Inc., 2021. UR...

  2. [2]

    Ashman, C

    M. Ashman, C. Ma, A. Hilmkil, J. Jennings, and C. Zhang. Causal reasoning in the presence of latent confounders via neural ADMG learning. In The Eleventh International Conference on Learning Representations, 2023. URL https://openreview.net/forum?id=dcN0CaXQhT

  3. [3]

    Barab \' a si and R

    A.-L. Barab \' a si and R. Albert. Emergence of scaling in random networks. Science, 286 0 (5439): 0 509--512, 1999. doi:10.1126/science.286.5439.509. URL https://www.science.org/doi/abs/10.1126/science.286.5439.509

  4. [4]

    Bhattacharya, T

    R. Bhattacharya, T. Nagarajan, D. Malinsky, and I. Shpitser. Differentiable causal discovery under unmeasured confounding. In A. Banerjee and K. Fukumizu, editors, Proceedings of The 24th International Conference on Artificial Intelligence and Statistics, volume 130 of Proceedings of Machine Learning Research, pages 2314--2322. PMLR, 13--15 Apr 2021. URL ...

  5. [5]

    Budhathoki, L

    K. Budhathoki, L. Minorics, P. Bl\" o baum, and D. Janzing. Causal structure-based root cause analysis of outliers. In K. Chaudhuri, S. Jegelka, L. Song, C. Szepesvari, G. Niu, and S. Sabato, editors, Proceedings of the 39th International Conference on Machine Learning, volume 162 of Proceedings of Machine Learning Research, pages 2357--2369. PMLR, 17--23...

  6. [6]

    B \"u hlmann, J

    P. B \"u hlmann, J. Peters, and J. Ernest. CAM : Causal additive models, high-dimensional order search and penalized regression. Annals of Statistics, 42 0 (6): 0 2526--2556, 2014 a

  7. [7]

    B \"u hlmann, J

    P. B \"u hlmann, J. Peters, and J. Ernest. CAM: Causal additive models, high-dimensional order search and penalized regression . The Annals of Statistics, 42 0 (6): 0 2526 -- 2556, 2014 b . doi:10.1214/14-AOS1260. URL https://doi.org/10.1214/14-AOS1260

  8. [8]

    Chen and C

    T. Chen and C. Guestrin. XGBoost : A scalable tree boosting system. In Proceedings of the 22nd ACM SIGKDD International Conference on Knowledge Discovery and Data Mining, KDD '16, pages 785--794, New York, NY, USA, 2016. ACM. ISBN 978-1-4503-4232-2. doi:10.1145/2939672.2939785. URL http://doi.acm.org/10.1145/2939672.2939785

  9. [9]

    W. Chen, Z. Huang, R. Cai, Z. Hao, and K. Zhang. Identification of causal structure with latent variables based on higher order cumulants. In Proceedings of the Thirty-Eighth AAAI Conference on Artificial Intelligence and Thirty-Sixth Conference on Innovative Applications of Artificial Intelligence and Fourteenth Symposium on Educational Advances in Artif...

  10. [10]

    D. M. Chickering. Optimal structure identification with greedy search. Journal of Machine Learning Research, 3 0 (Nov): 0 507--554, 2002

  11. [11]

    O. D. Duncan, D. L. Featherman, and B. Duncan. Socioeconomic Background and Achievement. Seminar Press, New York, 1972

  12. [12]

    Erd\" o s and A

    P. Erd\" o s and A. R\' e nyi. On random graphs I . Publicationes Mathematicae Debrecen, 6: 0 290, 1959

  13. [13]

    L. Ge, H. Cai, R. Wan, Y. Xu, and R. Song. A review of causal decision making, 2025. URL https://arxiv.org/abs/2502.16156

  14. [14]

    Glymour, K

    C. Glymour, K. Zhang, and P. Spirtes. Review of causal discovery methods based on graphical models. Frontiers in genetics, 10: 0 524, 2019

  15. [15]

    Gretton, K

    A. Gretton, K. Fukumizu, C. Teo, L. Song, B. Sch\" o lkopf, and A. Smola. A kernel statistical test of independence. In J. Platt, D. Koller, Y. Singer, and S. Roweis, editors, Advances in Neural Information Processing Systems, volume 20. Curran Associates, Inc., 2007. URL https://proceedings.neurips.cc/paper_files/paper/2007/file/d5cfead94f5350c12c322b5b6...

  16. [16]

    Hastie and R

    T. Hastie and R. Tibshirani. Generalized Additive Models . Statistical Science, 1 0 (3): 0 297 -- 310, 1986. doi:10.1214/ss/1177013604. URL https://doi.org/10.1214/ss/1177013604

  17. [17]

    P. O. Hoyer, S. Shimizu, A. Kerminen, and M. Palviainen. Estimation of causal effects using linear non- Gaussian causal models with hidden variables. International Journal of Approximate Reasoning, 49 0 (2): 0 362--378, 2008

  18. [18]

    P. O. Hoyer, D. Janzing, J. Mooij, J. Peters, and B. Sch\" o lkopf. Nonlinear causal discovery with additive noise models. In Advances in Neural Information Processing Systems 21 , pages 689--696. Curran Associates Inc., 2009

  19. [19]

    T. N. Maeda and S. Shimizu. RCD : Repetitive causal discovery of linear non- G aussian acyclic models with latent confounders. In Proc. 23rd International Conference on Artificial Intelligence and Statistics (AISTATS2010), volume 108 of Proceedings of Machine Learning Research, pages 735--745. PMLR, 26--28 Aug 2020

  20. [20]

    T. N. Maeda and S. Shimizu. Causal additive models with unobserved variables. In C. de Campos and M. H. Maathuis, editors, Proceedings of the Thirty-Seventh Conference on Uncertainty in Artificial Intelligence, volume 161 of Proceedings of Machine Learning Research, pages 97--106. PMLR, 27--30 Jul 2021. URL https://proceedings.mlr.press/v161/maeda21a.html

  21. [21]

    J. M. Ogarrio, P. Spirtes, and J. Ramsey. A hybrid causal search algorithm for latent variable models. In A. Antonucci, G. Corani, and C. P. Campos, editors, Proceedings of the Eighth International Conference on Probabilistic Graphical Models, volume 52 of Proceedings of Machine Learning Research, pages 368--379, Lugano, Switzerland, 06--09 Sep 2016. PMLR...

  22. [22]

    Peters, J

    J. Peters, J. M. Mooij, D. Janzing, and B. Sch\" o lkopf. Identifiability of causal graphs using functional models. In Proceedings of the Twenty-Seventh Conference on Uncertainty in Artificial Intelligence, UAI'11, page 589–598, Arlington, Virginia, USA, 2011. AUAI Press. ISBN 9780974903972

  23. [23]

    J. Runge. Conditional independence testing based on a nearest-neighbor estimator of conditional mutual information. In A. Storkey and F. Perez-Cruz, editors, Proceedings of the Twenty-First International Conference on Artificial Intelligence and Statistics, volume 84 of Proceedings of Machine Learning Research, pages 938--947. PMLR, 09--11 Apr 2018. URL h...

  24. [24]

    Salehkaleybar, A

    S. Salehkaleybar, A. Ghassami, N. Kiyavash, and K. Zhang. Learning linear non- G aussian causal models in the presence of latent variables. Journal of Machine Learning Research, 21: 0 39--1, 2020

  25. [25]

    Sch\" o lkopf

    B. Sch\" o lkopf. Causality for Machine Learning, page 765–804. Association for Computing Machinery, New York, NY, USA, 1 edition, 2022. ISBN 9781450395861. URL https://doi.org/10.1145/3501714.3501755

  26. [26]

    Schultheiss and P

    C. Schultheiss and P. B \"u hlmann. Assessing the overall and partial causal well-specification of nonlinear additive noise models. Journal of Machine Learning Research, 25 0 (159): 0 1--41, 2024. URL http://jmlr.org/papers/v25/23-1397.html

  27. [27]

    Servén and C

    D. Servén and C. Brummitt. pygam: Generalized additive models in python, Mar. 2018. URL https://doi.org/10.5281/zenodo.1208723

  28. [28]

    Shimizu, P

    S. Shimizu, P. O. Hoyer, A. Hyv \"a rinen, and A. Kerminen. A linear non- Gaussian acyclic model for causal discovery. Journal of Machine Learning Research, 7: 0 2003--2030, 2006

  29. [29]

    Shimizu, T

    S. Shimizu, T. Inazumi, Y. Sogawa, A. Hyv \"a rinen, Y. Kawahara, T. Washio, P. O. Hoyer, and K. Bollen. DirectLiNGAM : A direct method for learning a linear non- G aussian structural equation model. Journal of Machine Learning Research, 12: 0 1225--1248, 2011

  30. [30]

    Spirtes and C

    P. Spirtes and C. Glymour. An algorithm for fast recovery of sparse causal graphs. Social Science Computer Review, 9: 0 67--72, 1991

  31. [31]

    Spirtes, C

    P. Spirtes, C. Glymour, and R. Scheines. Causation, Prediction, and Search. MIT press, 2nd edition

  32. [32]

    Spirtes, C

    P. Spirtes, C. Meek, and T. Richardson. Causal inference in the presence of latent variables and selection bias. In Proc. 11th Annual Conference on Uncertainty in Artificial Intelligence (UAI1995) , pages 491--506, 1995

  33. [33]

    G. J. Sz \'e kely, M. L. Rizzo, and N. K. Bakirov. Measuring and testing dependence by correlation of distances . The Annals of Statistics, 35 0 (6): 0 2769 -- 2794, 2007. doi:10.1214/009053607000000505. URL https://doi.org/10.1214/009053607000000505

  34. [34]

    Tashiro, S

    T. Tashiro, S. Shimizu, A. Hyv \"a rinen, and T. Washio. ParceLiNGAM : A causal ordering method robust against latent confounders. Neural Computation, 26 0 (1): 0 57--83, 2014

  35. [35]

    Tramontano, Y

    D. Tramontano, Y. Kivva, S. Salehkaleybar, M. Drton, and N. Kiyavash. Causal effect identification in L i NGAM models with latent confounders. In R. Salakhutdinov, Z. Kolter, K. Heller, A. Weller, N. Oliver, J. Scarlett, and F. Berkenkamp, editors, Proceedings of the 41st International Conference on Machine Learning, volume 235 of Proceedings of Machine L...

  36. [36]

    Y. S. Wang and M. Drton. Causal discovery with unobserved confounding and non-gaussian data. J. Mach. Learn. Res., 24 0 (1), Jan. 2023. ISSN 1532-4435

  37. [37]

    Yokoyama, R

    H. Yokoyama, R. Shingaki, K. Nishino, S. Shimizu, and T. Pham. Causal-discovery-based root-cause analysis and its application in time-series prediction error diagnosis. arXiv preprint, 2025

  38. [38]

    Zhang, B

    K. Zhang, B. Sch \"o lkopf, and D. Janzing. Invariant Gaussian process latent variable models and application in causal discovery. In Proc. 26th Conference on Uncertainty in Artificial Intelligence (UAI2010) , pages 717--724, 2010

  39. [39]

    Zheng, B

    X. Zheng, B. Aragam, P. K. Ravikumar, and E. P. Xing. DAG s with NO TEARS : Continuous optimization for structure learning. In Advances in Neural Information Processing Systems, volume 31. Curran Associates, Inc., 2018