# Dataset provenance and handling

## Source

Development used the Kaggle dataset:

- **Project Euler Questions and Solutions**
- Creator: Dheeraj M Pai
- URL: https://www.kaggle.com/datasets/dheerajmpai/projecteuler
- Version observed: 1, last updated July 3, 2023
- Size: 773,683 bytes
- License shown by Kaggle API: **CC BY-NC-SA 4.0**

The Kaggle description says the dataset is intended for educational/non-commercial use and was shared with permission from the Project Euler team. Users remain responsible for checking the current dataset page, license, and Project Euler terms.

## Why the data is not committed

The machine repository is Apache-2.0. Bundling a CC BY-NC-SA corpus inside the package would create attribution, non-commercial, and share-alike obligations that should not be silently collapsed into the code license. The local importer preserves provenance while keeping generated data ignored.

## Observed archive structure

```text
Solutions.md.txt
  answer lines shaped like: <problem id>. <answer>

euler/<id>.html
  problem statements
```

Observed counts:

- 849 HTML problem files
- 840 parsed answers
- 840 IDs with both question and answer
- 20 questions referencing external document resources
- 163 questions containing image references
- 663 answer-covered questions with neither document nor image references

These counts describe the inspected archive and are not hard-coded expectations.

## External resources

Some questions cannot be solved from the HTML alone. For example, problem 22 references `resources/documents/0022_names.txt`. `prepare.py --fetch-resources` retrieves referenced document-like resources from `https://projecteuler.net/` and caches them under local ignored data.

Images are recorded separately. Some are decorative or redundant, such as problem 15's lattice illustration. Others may contain essential information. Before a long run, audit each newly reached image-bearing problem and either provide an accessible textual equivalent or mark it unavailable.

## Leakage boundary

`data/problems.jsonl` contains answers. It is evaluator-only and must never be copied into a rollout workspace or included with `@file` in Pi. Each workspace receives only:

- the selected question text;
- its assigned language/approach instructions;
- explicitly required resource files.

Raw rollouts may reveal answers and therefore also remain ignored.

## Contamination

Project Euler questions and answers are public and likely represented in pretraining corpora. Baseline success can reflect recall. Mitigations include measuring pre-training forward transfer, requiring executable solutions, inspecting code, creating parameterized variants, and reporting unrelated held-out benchmarks.