@article{4opsstructuraldifficultymodelinginintege,
  title = {4OPS: Structural Difficulty Modeling in Integer Arithmetic Puzzles},
  author = {Yunus E. Zeytuncu},
  year = {2026},
  eprint = {2603.25356},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2603.25356},
}