{
  "protocol": "temporal leave-one-out, three-way (train / val / test)",
  "fold_assignment": {
    "test": "last interaction per user",
    "val": "second-last interaction per user",
    "train": "all earlier interactions"
  },
  "temporal_scope": {
    "ordering": "per user, not global",
    "note": "Each user's own history is split chronologically, so no user's future leaks into their training data. Across users the folds overlap in wall-clock time: one user's training review can be later than another user's test review. This is the standard leave-last-one-out protocol; a single global cut-off date would be a different and stricter setting, and is not used here."
  },
  "relevance": {
    "definition": "implicit next-item: the chronologically next hotel the user reviewed",
    "all_ratings_are_positive": true,
    "relevance_threshold": null,
    "note": "Ratings are not thresholded by default; the holdout item is relevant because it was visited, not because it scored well."
  },
  "min_interactions": 4,
  "seed": 42,
  "n_users": 798,
  "n_items": 535,
  "n_train": 8645,
  "n_val": 798,
  "n_test": 798,
  "train_history_length": {
    "min": 2,
    "median": 5.0,
    "max": 208
  },
  "users_with_train_history_2": 183,
  "users_evaluated": {
    "val": 798,
    "test": 798
  },
  "sparsity_pct": 97.6012,
  "output_dir": "benchmark",
  "folds": {
    "train": {
      "n": 8645,
      "n_users": 798,
      "n_items": 508,
      "date_min": "2012-01-08",
      "date_max": "2023-12-06",
      "rating_mean": 7.5283
    },
    "val": {
      "n": 798,
      "n_users": 798,
      "n_items": 289,
      "date_min": "2015-10-20",
      "date_max": "2023-12-07",
      "rating_mean": 7.5561
    },
    "test": {
      "n": 798,
      "n_users": 798,
      "n_items": 278,
      "date_min": "2017-07-08",
      "date_max": "2023-12-09",
      "rating_mean": 7.4976
    }
  }
}