REVIEW 2 major objections 2 minor 13 references
Reviewed by Pith at T0; open to challenge.
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Hoeffding Concept Bottleneck Models replace linear aggregation with non-linear sparse concept combinations from tree decompositions.
2026-06-30 15:26 UTC pith:KSRVZIOS
load-bearing objection HCBM swaps the linear layer in CBMs for a Hoeffding decomposition of boosted trees to get sparse non-linear aggregations and a claimed proof of leakage robustness, but the proof may not fully address leakage already present in the concept scores. the 2 major comments →
Hoeffding Concept Bottleneck Models with Applications to Overhead Images
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
HCBM build on the Hoeffding functional decomposition of gradient-boosted trees to provide non-linear and sparse aggregations of concept scores, and generate compact predictions using prime implicants. HCBM are proved to be robust to interconcept leakage, and outperform standard linear CBM in practice, as shown in extensive experiments. Beyond classification, HCBM can be adapted to object detection, and we focus on a challenging case with overhead images to show the high performance of HCBM in these settings.
What carries the argument
Hoeffding functional decomposition of gradient-boosted trees applied to concept scores, yielding non-linear sparse aggregations and prime-implicant predictions.
Load-bearing premise
The true mapping from concept scores to output logits is non-linear, so the tree decomposition adds useful structure without creating fresh leakage or fitting problems.
What would settle it
An experiment in which a carefully tuned linear CBM matches or exceeds HCBM accuracy and leakage resistance on the overhead-image detection task would falsify the claimed advantage.
If this is right
- Predictions become expressible with far fewer active concepts via prime implicants.
- The same architecture extends directly from classification to object detection without new leakage.
- Extensive experiments confirm higher accuracy than linear CBMs on both standard benchmarks and overhead imagery.
- Robustness to inter-concept leakage holds by construction of the decomposition.
Where Pith is reading between the lines
- The sparsity induced by prime implicants may lower the cost of human review of model decisions in operational settings.
- The same decomposition could be applied to other high-level intermediate representations beyond the current concept sets.
- Testing the method on video or multi-view overhead sequences would check whether temporal consistency improves further.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper introduces Hoeffding Concept Bottleneck Models (HCBM), which apply the Hoeffding functional decomposition of gradient-boosted trees to concept scores in order to obtain non-linear, sparse aggregations via prime implicants. It claims a proof that HCBM are robust to interconcept leakage (unlike linear CBMs), reports superior empirical performance on classification tasks, and demonstrates an adaptation to object detection on overhead images.
Significance. If the robustness result holds with a complete derivation, the work would strengthen the case for non-linear yet interpretable concept-based models in high-stakes vision applications. The extension beyond classification to detection on overhead imagery is a concrete strength, and the use of an established functional decomposition (rather than a new ad-hoc aggregator) is a methodological plus.
major comments (2)
- [§4, Theorem 1] §4 (Robustness analysis), Theorem 1: the argument that the Hoeffding decomposition applied to upstream concept scores automatically eliminates interconcept leakage does not address the case in which the concept predictor itself has already encoded dependencies among concepts; no explicit bound or counter-example analysis is supplied showing that prime-implicant extraction remains leakage-free under realistic concept correlation.
- [§5, Tables 2–4] §5 (Experiments), Tables 2–4 and Figure 3: performance comparisons with linear CBMs are reported without error bars, statistical significance tests, or full dataset descriptions (including train/test splits and concept annotation protocol), which prevents verification that the claimed outperformance is stable rather than an artifact of post-hoc tree choices.
minor comments (2)
- [§3.3] Notation for the prime-implicant extraction step is introduced without a compact algorithmic listing; a short pseudocode block would improve reproducibility.
- [Abstract and §4] The abstract states that HCBM are “proved to be robust,” yet the main text does not include a self-contained proof sketch or reference to supplementary material containing the full derivation.
Simulated Author's Rebuttal
We thank the referee for the constructive comments. We respond to each major comment below and indicate planned revisions.
read point-by-point responses
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Referee: [§4, Theorem 1] §4 (Robustness analysis), Theorem 1: the argument that the Hoeffding decomposition applied to upstream concept scores automatically eliminates interconcept leakage does not address the case in which the concept predictor itself has already encoded dependencies among concepts; no explicit bound or counter-example analysis is supplied showing that prime-implicant extraction remains leakage-free under realistic concept correlation.
Authors: Theorem 1 establishes that, given concept scores as input, the Hoeffding decomposition followed by prime-implicant extraction yields an aggregation free of additional interconcept leakage (in contrast to linear CBMs). The proof concerns the aggregation step only and is conditional on the supplied scores. Dependencies that may already exist among the upstream concept predictions affect every CBM variant equally and lie outside the theorem's scope. We will add an explicit statement of this scope and the input-score assumption to the revised manuscript. revision: partial
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Referee: [§5, Tables 2–4] §5 (Experiments), Tables 2–4 and Figure 3: performance comparisons with linear CBMs are reported without error bars, statistical significance tests, or full dataset descriptions (including train/test splits and concept annotation protocol), which prevents verification that the claimed outperformance is stable rather than an artifact of post-hoc tree choices.
Authors: We agree that additional statistical detail and dataset documentation are required. The revised version will report error bars over multiple runs, include statistical significance tests, and supply complete descriptions of train/test splits together with the concept annotation protocol. revision: yes
Circularity Check
No circularity: derivation applies external Hoeffding decomposition to CBM scores without self-referential reduction
full rationale
The paper defines HCBM by importing the Hoeffding functional decomposition of gradient-boosted trees (an established external technique) and applying it to upstream concept scores to obtain non-linear sparse aggregations via prime implicants. The abstract states that HCBM 'are proved to be robust to interconcept leakage' as a claimed consequence of this application, but the provided text contains no equations, definitions, or self-citations that reduce the robustness claim, the non-linearity, or the predictions to a fitted parameter or ansatz defined inside the paper itself. No load-bearing step renames a known result, imports uniqueness from the authors' prior work, or treats a fitted input as a prediction. The central derivation therefore remains self-contained against external benchmarks and prior literature on Hoeffding decompositions and CBMs.
Axiom & Free-Parameter Ledger
axioms (1)
- domain assumption Hoeffding functional decomposition applies to the mapping from concept scores to output logits in gradient-boosted trees
read the original abstract
Explainability of deep learning algorithms is critical for computer-vision applications with high-stake decisions. Concept bottleneck models (CBM) have recently shown promising performance to provide explainable and accurate predictions for classification problems, based on a bottleneck of high-level concepts. Existing CBM methods rely on a linear aggregation of the concept scores to compute predictions. However, a large number of concepts is often used in this linear approach, which undermines explainability and favors information leakage. In general, the underlying relation between concepts and output logits is not linear. Therefore, we introduce Hoeffding Concept Bottleneck Models (HCBM), which build on the Hoeffding functional decomposition of gradient-boosted trees to provide non-linear and sparse aggregations of concept scores, and generate compact predictions using prime implicants. HCBM are proved to be robust to interconcept leakage, and outperform standard linear CBM in practice, as shown in extensive experiments. Beyond classification, HCBM can be adapted to object detection, and we focus on a challenging case with overhead images to show the high performance of HCBM in these settings.
Figures
Reference graph
Works this paper leans on
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Adebayo, J., Gilmer, J., Muelly, M., Goodfellow, I., Hardt, M., and Kim, B. (2018). Sanity checks for saliency maps. Advances in neural information processing systems,
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Hooker, G. (2007). Generalized functional anova diagnostics for high-dimensional functions of dependent variables. Journal of Computational and Graphical Statistics, 16:709–732. Ignatiev, A., Narodytska, N., and Marques-Silva, J. (2019). Abduction-based explanations for machine learning models. In AAAI, pages 1511–1519, Honolulu, Hawai. Koh, P. W., Nguyen...
work page internal anchor Pith review Pith/arXiv arXiv 2007
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[5]
We see that the component for g(1) recovers the logit f1 up to the intercept, and g(2) is very close to the null function. Therefore, TreeHFD automatically removes the concept score g(2) from the aggregation, despite its strong correlation with f1 and g(1), and HCBM are thus robust to interconcept leakage. This powerful property is a consequence of the un...
work page 1948
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[6]
The Hoeffding decomposition is a theoretical result, and its computation in practice is a difficult and open problem. When inputs are independent, closed formulas of the decomposition exist, but not when inputs are dependent, as it is the case in standard learning settings. When the input distribution is known, Lengerich et al. (2020) build on tree ensemb...
work page 2020
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[7]
circumvents this limitation and estimate the Hoeffding decomposition using tree ensembles and a data sample. D.2 TreeHFD The TreeHFD algorithm is introduced in Benard (2025), and the core principle is to discretize the Hoeffding decomposition using the tree partitions of a tree ensemble (e.g., gradient-boosting models, random forests...). Hence, the main ...
work page 2025
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[8]
onto background scenes from Places (Zhou et al., 2017). Waterbirds is designed to evaluate a model reliance on spurious correlations: during training, landbirds and waterbirds are predominantly paired with their typical land and water backgrounds respectively. However, these correlations are removed in the test set, creating a distribution shift which pen...
work page 2017
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[9]
to solve the multiclass logistic regression problem, with the elastic-net penalization originally introduced in PCBM (Yuksekgonul et al., 2023), that is an L1-ratio of 0.99, with a penalization strength set to meet the NEC input. EBM. EBM are probably the most widely used algorithm to build non-linear additive models (Nori et al., 2019). Hence, EBM can re...
work page 2023
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[10]
While linear CBM select about half of irrelevant concepts for all datasets, HCBM selects almost no irrelevant concepts. Compute resources. All experiments where conducted with a standard slurm HCP cluster, made of machines with 32 cores at 2.8 GHz and 384 GB of RAM. Software license. HCBM is based on XGBoost and TreeHFD. Consequently, xgboost and treehfd ...
work page 2012
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[11]
For linear CBM, we observe the positive concepts of “streetlights and road signs” and “regularly maintained and paved surfaces” for “Sea & Lake”, as mentioned in the article. For both linear CBM and HCBM, we observe concepts related to water surfaces, since the blue-green color of forests may induce a spurious association in Figure 6: For EuroSAT dataset,...
work page 2020
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[12]
onto background scenes from Places (Zhou et al., 2017). Waterbirds is designed to evaluate a model’s reliance on spurious correlations: during training, landbirds and waterbirds are predominantly paired with their typical land and water backgrounds respectively. However, these correlations are removed in the test set, creating a distribution shift which p...
work page 2017
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[13]
relied on “hooked seabird beak”, “duck-like body”, “gull-like body”, “tree-clinging-like body” for both classes. These concepts are considered bird-related concepts. Moreover, our model HCBM also relied on “harbor”, “lake”, “sea”, “tree”, “lacelike”, for both classes, and “matted” for the Landbird class and “porous” for the Waterbird class. We consider th...
work page 2026
discussion (0)
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