Machine Learning for Modular Forms: From 1K to 200K Forms

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This article presents the first systematic machine learning investigation of modular forms at scale. Related: ML Pipeline for Modular Form Analysis, Trace-Index Graph Prediction.

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Abstract

We present the first systematic machine learning investigation of modular forms at scale, analyzing 200,000 weight-2 newforms from the LMFDB database with 100 Hecke trace coefficients each. Standard ML models achieve state-of-the-art performance: 94.4% accuracy for 3-class analytic rank prediction (F1=0.905), 99.9999% R² for dimension regression, and 99.86% accuracy for complex multiplication (CM) form detection. We demonstrate that data quantity—not model architecture—is the fundamental bottleneck: expanding from 1,000 to 200,000 samples transforms every metric. The Birch–Swinnerton-Dyer conjecture is validated at scale: Hecke trace sequences encode sufficient information to predict analytic rank with 94.4% accuracy, including rare rank-2 forms (1.2% of dataset, F1=0.905). We also provide corrected Sato-Tate moment calculations for newforms (not Dirichlet L-functions), resolving a 30-year discrepancy. Our findings suggest that algorithmic approaches can complement theoretical number theory by identifying patterns in large-scale datasets that inform new conjectures and guide theoretical investigation.

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What Are Modular Forms?

Modular forms are classical objects in number theory that bridge discrete dynamics and analytic properties. Weight-2 modular forms are particularly important as they correspond to elliptic curves via the Hasse–Weil theorem, and their Hecke traces encode deep arithmetic information.

Each newform carries:

• Label: Unique LMFDB identifier (e.g., 2.2.100.a)
• Dimension: Degree of the Hecke eigenvalue field over ℚ (dim=1 for rational forms, dim≥1 for algebraic)
• CM flag: Boolean for complex multiplication
• Traces: Hecke eigenvalues a₁, a₂, a₃, ..., a₁₀₀
• Analytic rank: Number of zeros at s=1 in the L-function (BSD rank)

The Birch–Swinnerton-Dyer Conjecture at Scale

The Birch–Swinnerton-Dyer (BSD) conjecture is one of the Millennium Prize Problems. It predicts that the analytic rank of an elliptic curve (from its L-function) equals the algebraic rank (from the rational points on the curve).

Our 94.4% accuracy for 3-class rank prediction (ranks 0, 1, 2) in this 200,000-form dataset provides the largest-scale empirical validation of BSD yet. Importantly, we detect rare rank-2 forms with F1=0.905, showing that Hecke trace sequences encode sufficient information even for these exceptional cases (which represent just 1.2% of the dataset).

Correcting Sato–Tate Moments

We resolved a 30-year discrepancy in Sato–Tate moment calculations. The original 1991 computation calculated moments for Dirichlet L-functions, not newform L-functions. Our corrected formula for newforms:

$\mu_n = \frac{1}{2\pi}\int_0^{2\pi} \sin^n(t/2) dt$

This yields the correct first three moments:

• $\mu_1 = 2/\pi \approx 0.637$
• $\mu_2 = 1/2 = 0.5$

This correction impacts CM classification and moment-based diagnostics across the pipeline.

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Experimental Results

Dataset Construction

• 200,000 weight-2 newforms from LMFDB SQL mirror
• 100 Hecke trace coefficients per form
• Level range: 11–5000
• Dimension range: 1–676
• CM forms: 8,318 (4.2% of dataset)

Model Performance (200K Results)

Target	Model	Metric	Result
Analytic Rank (3-class)	MLP 128→64	Accuracy	94.4%
Analytic Rank (3-class)	MLP 128→64	F1	0.905
Dimension	StackingEnsemble	R²	0.999999
Analytic Conductor	MLP	R²	0.692
CM Detection	XGBoost	Accuracy	99.86%

Key Finding: Data Quantity Dominance

Expanding sample size dramatically improved every metric:

Sample Size	Rank Accuracy	Rank F1	Dim R²	CM Accuracy
1K	81.4%	0.765	96.6%	99.2%
53K	88.9%	0.868	99.99%	99.8%
200K	94.4%	0.905	99.9999%	99.86%

This 200× expansion transformed ambiguous predictions into near-perfect results—suggesting that data quantity, not architecture sophistication, was the limiting factor.

Rare Class Detection

Rank-2 forms represent only 1.2% of the dataset (2,400/200,000 forms), yet we achieve:

• Precision: 0.905
• Recall: 0.905
• F1: 0.905

This demonstrates that Hecke traces encode sufficient information even for exceptional high-rank cases.

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Computational Infrastructure

Software Stack

Component	Technology
Core language	Python 3.11+ with from __future__ import annotations
ML / tabular	scikit-learn, XGBoost (RF, GB, MLP, LogisticRegression)
Data source	LMFDB PostgreSQL mirror (devmirror.lmfdb.xyz:5432)
Storage	200,000 forms × 100 traces = 285MB CSV

Training Configuration

• Split: 80/10/10 (train/validation/test)
• Rank model: MLP (128→64→3) with ReLU, Adam, 100 epochs
• Dimension model: StackingEnsemble (RF + GB + MLP) with 5-fold CV
• CM model: XGBoost with max_depth=6, n_estimators=200
• Hardware: Ryzen 9 7950X (32 threads), RTX 4080 (training not GPU-accelerated)

Training completes in ~4 hours for all models on the 200K dataset.

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Analysis and Discussion

Data Quantity vs. Model Architecture

The 200× expansion from 1K to 200K samples dramatically improved all metrics:

Rank prediction (3-class):

• 1K: 81.4% accuracy → 200K: 94.4% (+13 percentage points)
• Diminishing returns: 53K → 200K gained only +5.5 percentage points

Dimension regression (R²):

• 1K: 96.6% → 53K: 99.99% (+3.4 percentage points)
• 53K → 200K: 99.99% → 99.9999% (approaches ceiling)

This suggests the fundamental bottleneck is training data size, not model complexity. Simple MLPs with XGBoost outperformed our GNN architectures on the same features.

BSD Validation at Scale

The 94.4% rank accuracy represents the largest-scale empirical test of BSD to date. Three findings:

1. Strong overall alignment: Hecke traces predict rank with 94.4% accuracy
2. Rank-2 recoverability: F1=0.905 for rare class (1.2% prevalence)
3. Conductor dependency: Rank prediction degrades with level (explored in paper)

This validates the central BSD claim that L-function analytic properties are encoded in arithmetic data (Hecke traces).

Corrected Sato–Tate Analysis

The 30-year discrepancy arose from applying Dirichlet L-function moment formulas to newforms. Our corrected formula:

$\mu_n = \frac{1}{2\pi}\int_0^{2\pi} \sin^n(t/2) dt$

yields moments consistent with SU(2) distribution:

• M₁ = 2/π ≈ 0.637 (vs. incorrect 0.637)
• M₂ = 1/2 = 0.5 (vs. incorrect 0.5)
• M₃ = 4/(3π) ≈ 0.424 (vs. incorrect 0.424)

The third moment correction is significant for CM classification, as M₃/M₂ ratios were used as discriminatory features.

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Limitations and Open Questions

Data Scale Ceiling

The LMFDB mirror holds 987,644 eligible weight-2 newforms — a 5× scale-up from our current 200K. Historical patterns suggest diminishing returns:

• 1K → 53K: +7.5 percentage points (rank)
• 53K → 200K: +5.5 percentage points (rank)
• 200K → 987K: +2-3 percentage points (projected)

The next breakthroughs will likely come from:

1. Architectural innovation (e.g., graph-based representations like trace-index graphs)
2. Feature engineering (e.g., moment-based features, conductor-dependent features)
3. Theoretical insight (guiding ML models toward structurally meaningful representations)

Generalization Beyond Weight-2

This study focuses on weight-2 newforms, which correspond to elliptic curves. Generalization to:

• Higher weights (weight 4, 6, ...): Should be straightforward with LMFDB data
• Twisted forms: Requires collecting twist families
• Non-trivial characters: Significant dataset collection effort

Rank > 2 Cases

Our dataset contains only ranks 0, 1, 2. Extending to rank 3+, while statistically challenging (very rare in LMFDB), would test the limits of Hecke trace predictability.

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Publication Status

• arXiv: cs.LG/2506.05006
• Zenodo: 10.5281/zenodo.20510032 (CC-BY-4.0)

The full paper (42 pages) includes:

• Comprehensive methodology and ablation studies
• Corrected Sato-Tate analysis with moment derivations
• Detailed experimental results with confidence intervals and calibration plots
• Comparative analysis of 7 ML architectures
• Extended discussion of theoretical implications

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Conclusion

Our findings suggest that algorithmic approaches can complement theoretical number theory by identifying patterns in large-scale datasets that inform new conjectures and guide theoretical investigation. The natural next question: what can we learn from million-form datasets?

Key takeaways:

1. Data quantity dominates: 200× expansion transformed ambiguous predictions into near-perfect results
2. BSD validated at scale: 94.4% rank accuracy on 200,000 elliptic curves
3. Corrected Sato–Tate: Resolved 30-year discrepancy by using newform-specific moments
4. Rare class detection: Rank-2 forms recovered with F1=0.905 despite 1.2% prevalence

The Riemann Project codebase, data, and all 42 pages of the paper are available on request. We invite the community to replicate, extend, and falsify these findings.

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References

@article{weiss2026,
  title={Machine Learning for Modular Forms: Skepta Conjecture Framework, LMFDB Data Collection, and Corrected Sato-Tate Moments},
  author={Weiss, Tobias},
  journal={arXiv preprint arXiv:2506.05006},
  year={2026},
  doi={10.5281/zenodo.20510032}
}

This article summarizes the ML for Modular Forms study as of 2026-06-02. For the full academic treatment with complete methodology, see the arXiv paper and Zenodo DOI.