REVIEW 3 major objections 5 minor 30 references
This paper claims that agentic workflow synthesis can be done at test time, without any training, by jointly searching over a task-decomposition topology and executable sub-workflows, with execution feedback able to reshape the topology its
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
2026-08-02 13:32 UTC pith:IPPLS4FT
load-bearing objection HierFlow's coupled topology–execution search and gating knob are genuinely new, and the paper is unusually honest about its own limits, but the empirical 'consistently outperforms' claim needs paired statistics and cleaner baselines before it lands. the 3 major comments →
Coupled Hierarchical Search over Topology and Execution for Agentic Workflow Synthesis
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
On the paper's own terms, the central discovery is that the workflow itself is a coupled structure–execution state: a directed acyclic graph of subtasks together with an executable sub-workflow attached to each node. Both components are searched simultaneously: the topology defines the code-search domain for each subtask, and failures or low confidence in the lower-level execution can trigger a topology revision that adds, removes, or rewires subtasks and rewinds execution. HierFlow instantiates this with an LLM-driven upper-level refiner, an MCTS-inspired lower-level tree search with execution-grounded evaluation, and a gating mechanism that activates lower-level search only when a search-n
What carries the argument
The load-bearing machinery is the coupled dual-space proxy: an upper-level topology space of DAG task decompositions and a lower-level space of executable code sub-workflows, searched jointly. Three mechanisms carry the argument: (i) a LLM-based topology refiner that scores candidate decompositions with a weighted objective including a dependency-complexity term, (ii) a lightweight MCTS-inspired tree search that iterates selection, expansion, evaluation (including a hard sandbox executability check), and information propagation without score backpropagation to parents, and (iii) a gating module that uses the search necessity proxy Z_i = S_i * U_i, where S_i is log remaining candidate space a
Load-bearing premise
The central load-bearing premise is that the LLM-based evaluator's quality scores are a faithful proxy for end-task correctness when ranking candidate sub-workflows and when computing the gating signal; if this alignment weakens on new tasks or distributions, both the lower-level search and the gating decision will select suboptimal workflows.
What would settle it
A concrete experiment that would settle the claim: on a new distribution, compute the Spearman correlation between the gating proxy Z_i and the realized quality gain from forcing lower-level search; if this correlation is not significantly positive, or if the stratified improvement rate does not increase with Z_i, the gating mechanism's justification fails. Likewise, on a task with deliberately high cross-subtask coupling (e.g., steps that must share and update global state), the predicted degradation should appear: the system's cost–quality trade-off should cease to beat a flat MCTS-in-code b
If this is right
- If the central claim holds, automatic workflow generation no longer requires offline search over a fixed dataset or training a designer; a query-level, training-free search can match or exceed those methods.
- The gating threshold τ gives users an interpretable control knob for test-time scaling: smaller τ buys accuracy with more compute, larger τ saves cost, and the operating point near the knee of the Pareto curve is competitive with the best baseline.
- Execution feedback into topology revision means the system can recover from poor initial decompositions mid-query, which is a capability that fixed-topology or offline-searched workflows lack.
- The coupling-aware analysis predicts that the advantage of hierarchical splitting shrinks as cross-subtask dependency density or repair rate grows, so the method's target regime is moderately decomposable tasks.
- LLM-based evaluation, despite its known pitfalls, is claimed to be reliable enough for search guidance: on MATH the lower-level evaluator agrees with end-task success in 85.8% of cases, and swapping judge models shifts accuracy by about one point.
Where Pith is reading between the lines
- The rank-based gating theorem suggests a general recipe: any proxy that ranks subtasks by expected search gain can be plugged into the same budget-allocation framework. Z_i = S_i * U_i is one instantiation; a natural extension would be to use a cheap learned surrogate of realized gain, or an ensemble of uncertainty measures, without giving up the training-free property.
- The observable coupling proxy could be used as a per-query diagnostic: compute it before or during search to decide when to switch to flat code search or to adjust the gating threshold, potentially making the method robust to tasks that violate the moderate-coupling assumption.
- Because the lower-level search is execution-grounded with mock inputs, the method transfers to any domain with a sandbox and a schema-consistent input generator—for example formal proof verification, SQL query generation, or tool-use workflows where execution feedback is available. This is a testable extension, not something the paper claims.
- The memory bank that reuses sub-workflow configurations across semantically similar subtasks suggests a form of amortized test-time search; across a stream of queries, the system could accumulate reusable components without training, which the paper does not explore.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. HierFlow is proposed as a training-free, test-time hierarchical search framework for agentic workflow synthesis. It searches jointly over an upper-level task-topology space and a lower-level code-execution space, with a gating mechanism that decides when to invoke execution-level search. The paper claims consistent state-of-the-art results on HotpotQA, GSM8K, MATH, MBPP, and HumanEval, and supports the design with a coupling-aware cost analysis, a rank-based gating analysis, ablations, and evaluator-robustness checks.
Significance. If the central empirical claim holds, HierFlow is a useful contribution: it combines two complementary proxy spaces in a training-free manner, offers a tunable quality–cost trade-off through the gating threshold, and includes several honest robustness analyses (judge-model sensitivity, evaluator–end-task agreement, direct gating-proxy validation). The theoretical results are correctly framed as cost-accounting and rank-bound statements rather than unconditional guarantees. However, the main empirical claim of consistent superiority is currently supported only by point estimates with overlapping standard deviations, and one baseline is confounded by a different base model. These issues are fixable but load-bearing.
major comments (3)
- [§3.2, Table 1] The central claim of consistent superiority rests on point estimates whose headline margins are within one standard deviation of the runner-up on three of five benchmarks: GSM8K 92.70±0.35 vs MaAS 92.51±0.39 (Δ=0.19), MBPP 82.40±0.77 vs MaAS 82.11±0.84 (Δ=0.29), and HumanEval 93.13±0.88 vs DyFlow 92.37±0.79 (Δ=0.76). With only three aggregate runs and no paired significance tests, confidence intervals, or effect sizes, the abstract's 'consistently outperforms' is under-evidenced. Please add per-example paired tests (e.g., bootstrap or Wilcoxon signed-rank over the test sets of size n=800/1055/486/131/341) and report CIs; otherwise the claim should be weakened.
- [§3.1/Appendix D.2, Table 1] The comparison to DyFlow is confounded by base model: 'The only exception is DyFlow, for which we directly adopt its pre-trained designer based on Phi-4' (Appendix D.2), while HierFlow and all other baselines use gpt-4o-mini. DyFlow is the runner-up on MATH and HumanEval, the two benchmarks where the claimed advantage is largest. Since base-model capability can explain part of this gap, the method-level comparison requires either a DyFlow variant with a gpt-4o-mini designer or a Phi-4-based HierFlow run. Without this, the headline margins over DyFlow are not attributable to the search mechanism.
- [Appendix D.5, Definition 2.5] The validation of the gating proxy is partially self-referential: ΔQ_i is computed as Q_i(after lower-level search) − Q_i(baseline IO), where Q_i is the same LLM evaluator Jsub used by the lower-level search, and Z_i uses the predictive entropy of rationales produced by the same evaluator. A positive Spearman ρ=0.43 may therefore reflect evaluator self-consistency rather than alignment with end-task correctness. Please report the rank correlation of Z_i with externally measured gains (e.g., final pass@1/accuracy on the test examples) or with a different judge model, and stratify improvement rates by external correctness. The current 85.8% evaluator–end-task agreement (Table 7) does not directly establish proxy informativeness.
minor comments (5)
- [§3.4, Table 2] The header 'Training ↓ Testing MATH HumanEval GSM8K MBPP HotpotQA' is ambiguous, and the HotpotQA values for DyFlow (68.13) and Flow (67.88) differ from Table 1 (67.88 and 67.63). Please clarify the transfer protocol and reconcile the numbers.
- [§2.3] Typo: 'he search process' should read 'The search process'.
- [References] References [24] and [25] appear to be the same citation; [25] should cite the Self-Consistency paper, not the CoT paper.
- [§3.1] The text says 'Results average three independent runs' but does not report seeds or explain the variance source. Please add this information or per-run results for the main table.
- [Figure 3] Minor formatting: 'MATHdataset' should be 'MATH dataset'; the 'A vg.' label in Table 1 should be 'Avg.'
Circularity Check
Gating-proxy validation is partly self-referential, but the headline benchmark results are external and not circular.
specific steps
-
other
[Appendix D.5 (Empirical Validation of the Gating Proxy), combined with Sec. 2.3 Evaluation and Definition 2.4]
"For each candidate node encountered during upper-level traversal, we record its proxy value Zi before the gating decision and then force the lower-level search to be invoked under a fixed budget, regardless of whether the gating rule would have triggered it. We measure the realized quality gain ΔQi = Qi(after lower-level search)−Qi(baseline IO solution), where the baseline corresponds to the root node produced by direct input–output generation."
The gating proxy Zi = Si·Ui includes Ui, the predictive entropy of the evaluation rationale ri produced by the LLM-based evaluator Jsub, and the same Jsub assigns the quality scores whose difference defines ΔQi. The reported Spearman ρ=0.43 and the stratified improvement rates therefore partly measure whether the evaluator's own rationale uncertainty predicts its own score gain, rather than independently validating that gating selects subtasks that improve end-task correctness. This is not full circularity because Zi and ΔQi are distinct quantities and Table 1 reports external pass@1/F1/accuracy, but it is a self-referential supporting validation.
full rationale
I find no step in which the paper's central benchmark claim reduces by construction to its inputs. Theorem 2.2 is an explicit bookkeeping decomposition of test-time cost, and the paper itself labels it a 'coupling-aware characterization rather than an unconditional asymptotic speedup guarantee' (Remark 2.3). Theorem 2.6 is a rank-disagreement bound that explicitly disclaims unconditional near-optimality. The final Table 1 numbers are scored by external metrics (F1, accuracy, pass@1), so the main 'consistently outperforms' claim is not circular in the sense of being equivalent to a fitted quantity. The one genuine circularity concern is the gating validation in Appendix D.5: the realized gain ΔQi is computed from the same LLM evaluator that supplies the uncertainty component of the gating proxy Zi, so the reported rank correlation and improvement rates are partly self-referential. The paper partially mitigates this with judge-model sensitivity and end-task-agreement analyses (Appendix D.4), and the gating validation is supporting rather than load-bearing for the headline result. There is also a minor self-citation in the introduction ('test-time scaling has emerged ... [16]', where [16] is the authors' own SolverLLM), but this is not load-bearing because the test-time scaling paradigm is independently established and the method's design does not rest on that specific prior result. Overall, the derivation is largely self-contained, with one partial self-referential validation, corresponding to a score of 4.
Axiom & Free-Parameter Ledger
free parameters (7)
- Gating threshold τ =
4
- Refinement signal threshold γ (Eq. 3) =
not specified
- Lower-level selection parameters α, λp =
α=0.4, λp=0.3
- Topology scoring weights λ0, λcov, λsnd, λsea =
uniform
- Coupling proxy weights β, η (Eq. 1) =
unspecified
- Memory bank thresholds α=0.5, θ=0.85 =
0.5, 0.85
- Search budgets dmax=3, bmax=3, ccmax=5, K=3, ctmax=20 =
3,3,5,3,20
axioms (5)
- domain assumption LLM evaluator quality scores align with end-task correctness
- domain assumption Topological layer-wise execution is a valid decomposition for the target tasks
- domain assumption The search-space estimate |W_i| ≈ b_max^{d_max} governs search potential
- standard math Standard combinatorial and statistical results (Kahn's algorithm, Softmax selection, Spearman correlation)
- ad hoc to paper Observable coupling proxy κ̂(G) is a meaningful measure of cross-task coupling
invented entities (1)
-
Search necessity proxy Z_i = S_i · U_i
no independent evidence
read the original abstract
Although structured workflows empower Large Language Models (LLMs) to tackle complex problems, automating their creation is severely hindered by a vast combinatorial search space, frequently resulting in inflexible and resource-heavy offline training dependencies. To address this, we conceptualize workflow generation as an intertwined topology-and-execution search paradigm, where the broader topological layer dictates subtask boundaries and lower-level execution outcomes actively reshape the topology itself. Building on this foundation, we introduce HierFlow, a training-free, test-time hierarchical search architecture that automates agentic workflow design by merging feedback-guided topology adjustments with a fast, MCTS-inspired tree search for sub-workflow optimization. HierFlow maximizes efficiency through an intelligent gating module that selectively triggers execution-level searches based on contextual necessity, a mechanism we further support with an in-depth analysis detailing how varying degrees of cross-task coupling impact the effectiveness of hierarchical splitting. Comprehensive testing across question answering, mathematical reasoning, and code generation benchmarks confirms that HierFlow consistently outperforms strong baselines, delivering an optimal balance of high-quality results and computational efficiency without any additional training overhead.
Figures
Reference graph
Works this paper leans on
-
[1]
M. Abdin, J. Aneja, H. Behl, S. Bubeck, R. Eldan, S. Gunasekar, M. Harrison, R. J. Hewett, M. Javaheripi, P. Kauffmann, et al. Phi-4 technical report.arXiv preprint arXiv:2412.08905, 2024
Pith/arXiv arXiv 2024
-
[2]
D. B. Acharya, K. Kuppan, and B. Divya. Agentic ai: Autonomous intelligence for complex goals–a comprehensive survey.IEEe Access, 2025
2025
-
[3]
N. Astorga, T. Liu, Y. Xiao, and M. van der Schaar. Autoformulation of mathematical optimization models using llms.arXiv preprint arXiv:2411.01679, 2024. 11
Pith/arXiv arXiv 2024
-
[4]
J. Austin, A. Odena, M. Nye, M. Bosma, H. Michalewski, D. Dohan, E. Jiang, C. Cai, M. Terry, Q. Le, et al. Program synthesis with large language models.arXiv preprint arXiv:2108.07732, 2021
Pith/arXiv arXiv 2021
-
[5]
Besta, N
M. Besta, N. Blach, A. Kubicek, R. Gerstenberger, M. Podstawski, L. Gianinazzi, J. Gajda, T. Lehmann, H. Niewiadomski, P. Nyczyk, et al. Graph of thoughts: Solving elaborate problems with large language models. InProceedings of the AAAI conference on artificial intelligence, volume 38, pages 17682–17690, 2024
2024
-
[6]
M. Chen, J. Tworek, H. Jun, et al. Evaluating large language models trained on code. 2021
2021
-
[7]
K. Cobbe, V. Kosaraju, M. Bavarian, M. Chen, H. Jun, L. Kaiser, M. Plappert, J. Tworek, J. Hilton, R. Nakano, et al. Training verifiers to solve math word problems.arXiv preprint arXiv:2110.14168, 2021
Pith/arXiv arXiv 2021
-
[8]
Y. Du, S. Li, A. Torralba, J. B. Tenenbaum, and I. Mordatch. Improving factuality and reasoning in language models through multiagent debate. InForty-first International Conference on Machine Learning, 2023
2023
-
[9]
J. Fang, Y. Peng, X. Zhang, Y. Wang, X. Yi, G. Zhang, Y. Xu, B. Wu, S. Liu, Z. Li, et al. A comprehensive survey of self-evolving ai agents: A new paradigm bridging foundation models and lifelong agentic systems.arXiv preprint arXiv:2508.07407, 2025
Pith/arXiv arXiv 2025
-
[10]
D. Hendrycks, C. Burns, S. Kadavath, A. Arora, S. Basart, E. Tang, D. Song, and J. Stein- hardt. Measuring mathematical problem solving with the math dataset.arXiv preprint arXiv:2103.03874, 2021
Pith/arXiv arXiv 2021
-
[11]
S. Hu, C. Lu, and J. Clune. Automated design of agentic systems.arXiv preprint arXiv:2408.08435, 2024
Pith/arXiv arXiv 2024
-
[12]
Hughes, Y
L. Hughes, Y. K. Dwivedi, T. Malik, M. Shawosh, M. A. Albashrawi, I. Jeon, V. Dutot, M. Appanderanda, T. Crick, R. De’, et al. Ai agents and agentic systems: A multi-expert analysis.Journal of Computer Information Systems, pages 1–29, 2025
2025
-
[13]
A. Hurst, A. Lerer, A. P. Goucher, A. Perelman, A. Ramesh, A. Clark, A. Ostrow, A. Welihinda, A. Hayes, A. Radford, et al. Gpt-4o system card.arXiv preprint arXiv:2410.21276, 2024
Pith/arXiv arXiv 2024
-
[14]
S. Kadavath, T. Conerly, A. Askell, T. Henighan, D. Drain, E. Perez, N. Schiefer, Z. Hatfield- Dodds, N. DasSarma, E. Tran-Johnson, et al. Language models (mostly) know what they know. arXiv preprint arXiv:2207.05221, 2022
Pith/arXiv arXiv 2022
-
[15]
A. B. Kahn. Topological sorting of large networks.Communications of the ACM, 5(11):558–562, 1962
1962
-
[16]
D. Li, X. Zhao, L. Yu, Y. Liu, W. Cheng, Z. Chen, Z. Chen, F. Chen, C. Zhao, and H. Chen. Solverllm: Leveraging test-time scaling for optimization problem via llm-guided search.arXiv preprint arXiv:2510.16916, 2025
arXiv 2025
-
[17]
X. Li, S. Wang, S. Zeng, Y. Wu, and Y. Yang. A survey on llm-based multi-agent systems: workflow, infrastructure, and challenges.Vicinagearth, 1(1):9, 2024
2024
-
[18]
Z. Li, S. Xu, K. Mei, W. Hua, B. Rama, O. Raheja, H. Wang, H. Zhu, and Y. Zhang. Autoflow: Automated workflow generation for large language model agents.arXiv preprint arXiv:2407.12821, 2024. 12
Pith/arXiv arXiv 2024
-
[19]
Madaan, N
A. Madaan, N. Tandon, P. Gupta, S. Hallinan, L. Gao, S. Wiegreffe, U. Alon, N. Dziri, S. Prabhumoye, Y. Yang, et al. Self-refine: Iterative refinement with self-feedback.Advances in Neural Information Processing Systems, 36:46534–46594, 2023
2023
-
[20]
B. Niu, Y. Song, K. Lian, Y. Shen, Y. Yao, K. Zhang, and T. Liu. Flow: Modularized agentic workflow automation.arXiv preprint arXiv:2501.07834, 2025
Pith/arXiv arXiv 2025
-
[21]
S. Qiao, R. Fang, Z. Qiu, X. Wang, N. Zhang, Y. Jiang, P. Xie, F. Huang, and H. Chen. Benchmarking agentic workflow generation.arXiv preprint arXiv:2410.07869, 2024
Pith/arXiv arXiv 2024
-
[22]
Singh, A
A. Singh, A. Ehtesham, S. Kumar, and T. T. Khoei. Enhancing ai systems with agentic workflows patterns in large language model. In2024 IEEE World AI IoT Congress (AIIoT), pages 527–532. IEEE, 2024
2024
-
[23]
Y. Wang, Z. Xu, Y. Huang, X. Wang, Z. Song, L. Gao, C. Wang, X. Tang, Y. Zhao, A. Co- han, et al. Dyflow: Dynamic workflow framework for agentic reasoning.arXiv preprint arXiv:2509.26062, 2025
arXiv 2025
-
[25]
J. Wei, X. Wang, D. Schuurmans, M. Bosma, F. Xia, E. Chi, Q. V. Le, D. Zhou, et al. Chain-of-thought prompting elicits reasoning in large language models.Advances in neural information processing systems, 35:24824–24837, 2022
2022
-
[26]
S. Xu, J. Zhang, S. Di, Y. Luo, L. Yao, H. Liu, J. Zhu, F. Liu, and M.-L. Zhang. Robustflow: Towards robust agentic workflow generation.arXiv preprint arXiv:2509.21834, 2025
arXiv 2025
-
[27]
Z. Yang, P. Qi, S. Zhang, Y. Bengio, W. Cohen, R. Salakhutdinov, and C. D. Manning. Hotpotqa: A dataset for diverse, explainable multi-hop question answering. InProceedings of the 2018 conference on empirical methods in natural language processing, pages 2369–2380, 2018
2018
-
[28]
S. Yao, D. Yu, J. Zhao, I. Shafran, T. Griffiths, Y. Cao, and K. Narasimhan. Tree of thoughts: Deliberate problem solving with large language models.Advances in neural information processing systems, 36:11809–11822, 2023
2023
-
[29]
C. Yu, Z. Cheng, H. Cui, Y. Gao, Z. Luo, Y. Wang, H. Zheng, and Y. Zhao. A survey on agent workflow–status and future. In2025 8th International Conference on Artificial Intelligence and Big Data (ICAIBD), pages 770–781. IEEE, 2025
2025
-
[30]
G. Zhang, L. Niu, J. Fang, K. Wang, L. Bai, and X. Wang. Multi-agent architecture search via agentic supernet.arXiv preprint arXiv:2502.04180, 2025
Pith/arXiv arXiv 2025
-
[31]
J. Zhang, J. Xiang, Z. Yu, F. Teng, X. Chen, J. Chen, M. Zhuge, X. Cheng, S. Hong, J. Wang, et al. Aflow: Automating agentic workflow generation.arXiv preprint arXiv:2410.10762, 2024. 13 A Related Work Workflow Representation via Proxy Spaces.Since direct search over the workflow space is highly challenging, existing approaches typically reformulate workf...
Pith/arXiv arXiv 2024
discussion (0)
Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.