{
  "version": "v3.2",
  "generated_utc": "19 September 2026",
  "track": "best",
  "other_track": "constrained",
  "methodology": {
    "index_name": "Recommender Performance Index",
    "index_short": "RPI",
    "value_index_name": "Recommender Value Index",
    "value_index_short": "RVI",
    "value_index_note": "quality per dollar, expressed as a ratio to ItemKNN, which therefore reads exactly 100 here by definition. Quality-per-dollar has no natural unit and a bare ratio is unreadable, so the scale borrows one — this is a declared unit, not a statement about where ItemKNN places. Its position on the quality index is measured like every other system's.",
    "version": "v3.1",
    "frozen_at": "2026-08-22T00:00:00Z",
    "fingerprint": "52706396658de50c",
    "calibration": {
      "state": "frozen",
      "fingerprint": "05eb9f3f645e581b",
      "minted_at": "2026-08-23T13:27:52Z",
      "n_constants": 167,
      "note": "the field for each metric and dataset is a fixed list of numbers published in configs/v3_calibration.json, so every system including the two reference systems is scored against a distribution that does not move when the leaderboard grows"
    },
    "normalisation": "frozen-field percentile: a system's score on a metric is where its measurement falls in the distribution of every entrant's measurement on that metric and dataset, pooled across the calibrating release's runs and then frozen. Nothing is anchored to a chosen system, so the scale cannot invert or explode, and no system is pinned to either end. Freezing the field is what keeps adding an entrant from moving anyone else's score.",
    "normalisation_id": "frozen_field_percentile",
    "supersedes": "v3.0 used a two-point anchored scale dividing by (itemknn - popularity). It was withdrawn: on two of ten datasets that difference was negative, inverting the scale, and where it was small a worse result could reach -381 before being floored. Scores are not comparable across the change.",
    "clip": [
      0,
      100
    ],
    "saturation": "a percentile is bounded; a system beyond either end of the frozen field saturates at 0 or 100 on that metric, and how often that happens is reported",
    "dimension_weights": {
      "relevance": 0.35,
      "cold_start": 0.15,
      "long_tail": 0.15,
      "beyond_accuracy": 0.1,
      "multi_objective": 0.1,
      "robustness": 0.15
    },
    "consistency": "reported as a separate `spread` column (cross-dataset standard deviation of the relevance dimension), not scored: how much to penalise a system that wins on one dataset and loses on another is a judgement about what the reader wants, not a measurement",
    "dimension_metrics": {
      "relevance": {
        "ndcg@10": {
          "weight": 0.45,
          "higher_is_better": true
        },
        "recall@20": {
          "weight": 0.3,
          "higher_is_better": true
        },
        "mrr@10": {
          "weight": 0.15,
          "higher_is_better": true
        },
        "hitrate@10": {
          "weight": 0.1,
          "higher_is_better": true
        }
      },
      "cold_start": {
        "cohort:cold_users_1_4:ndcg@10": {
          "weight": 0.45,
          "higher_is_better": true
        },
        "cohort:cold_items:ndcg@10": {
          "weight": 0.35,
          "higher_is_better": true
        },
        "cohort:new_items_since_train:ndcg@10": {
          "weight": 0.2,
          "higher_is_better": true
        }
      },
      "long_tail": {
        "cohort:tail_target_items:ndcg@10": {
          "weight": 0.4,
          "higher_is_better": true
        },
        "tail_share@20": {
          "weight": 0.3,
          "higher_is_better": true
        },
        "coverage@20": {
          "weight": 0.3,
          "higher_is_better": true
        }
      },
      "beyond_accuracy": {
        "novelty@20": {
          "weight": 0.35,
          "higher_is_better": true
        },
        "ild@20": {
          "weight": 0.35,
          "higher_is_better": true
        },
        "popularity_percentile@20": {
          "weight": 0.15,
          "higher_is_better": false
        },
        "provider_gini": {
          "weight": 0.15,
          "higher_is_better": false
        }
      },
      "multi_objective": {
        "mo_weighted_utility": {
          "weight": 0.65,
          "higher_is_better": true
        },
        "mo_negative_signal_rate": {
          "weight": 0.35,
          "higher_is_better": false
        }
      },
      "robustness": {
        "cohort:sparse_history:ndcg@10": {
          "weight": 0.35,
          "higher_is_better": true
        },
        "cohort:dense_history:ndcg@10": {
          "weight": 0.25,
          "higher_is_better": true
        },
        "cohort:heavy_users_20plus:ndcg@10": {
          "weight": 0.2,
          "higher_is_better": true
        },
        "cohort:warm_users_5_19:ndcg@10": {
          "weight": 0.2,
          "higher_is_better": true
        }
      }
    },
    "aggregation": "mean percentile across datasets per metric, then weighted mean within each dimension, then weighted mean across dimensions; dimensions with no measurable metric are dropped and the remaining weights renormalised",
    "quality_only": "cost, latency, model size and retraining burden are NOT inputs to this index; they are reported separately and combined only in the Recommender Value Index"
  },
  "reference_deployment": {
    "active_users": 1000000,
    "slates_per_user_per_month": 10,
    "retrains_per_month": 4.35,
    "serving_utilisation": 0.35,
    "slates_per_month": 10000000,
    "note": "stated assumption, not a measurement; the per-slate and per-retrain figures it multiplies ARE measured"
  },
  "uncalibrated_datasets": [],
  "leaderboard": [
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      "key": "itemknn_multitask",
      "system": "ItemKNN + Multi-task ranker",
      "index": 68.82,
      "family": "multi-stage",
      "generative": false,
      "confidence": "reproduction",
      "origin": "Multi-task ranking over several engagement signals",
      "citation": "Ma et al., 'Modeling Task Relationships in Multi-task Learning with Multi-gate Mixture-of-Experts', KDD 2018; Zhao et al., 'Recommending What Video to Watch Next', RecSys 2019.",
      "summary": "A neighbourhood model produces the candidates, and the ranking stage carries one output head per logged engagement signal — click, long view, like, share, follow, and the negative signals — combined into a single order by weights fixed before any result was measured (Ma et al., KDD 2018). On a dataset that logs only one signal there is only one head, and it is reported as a pointwise ranker there.",
      "stages": "retrieval + multi-task ranking",
      "proxy_of": null,
      "proxy_caveat": null,
      "introduced_in": null,
      "native_retriever": "itemknn",
      "retriever_label": null,
      "ranker_label": "Multi-task ranker",
      "is_new": false,
      "dimensions": {
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        "cold_start": 63.93,
        "long_tail": 50.26,
        "beyond_accuracy": 53.11,
        "multi_objective": 69.64,
        "robustness": 78.46
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      "per_dataset_relevance": {
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        "hm-fashion": 81.9047619047619,
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        "ml-32m": 71.41304347826087,
        "retailrocket": 69.45652173913044
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      "monthly_cost_usd": 64.24727830912043,
      "train_cost_usd": 0.005819726882651014,
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      "latency_caveat": "includes constructing the ranker's features online, in Python, for every request — work a deployed pipeline precomputes or caches, so this is an upper bound",
      "value_index": 7.712291872701536,
      "other_track_index": 69,
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    {
      "rank": 2,
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      "summary": "A neighbourhood model produces a few hundred candidates and a multilayer perceptron reorders them, over features combining the retrieval score, item and user statistics, and content similarity. The retriever is fitted on the training window, the ranker is trained on candidates labelled from the validation window, and the retriever is refitted for serving; every part of that cost is charged to the system.",
      "stages": "retrieval + ranking",
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      "per_dataset_relevance": {
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      "latency_caveat": "includes constructing the ranker's features online, in Python, for every request — work a deployed pipeline precomputes or caches, so this is an upper bound",
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    {
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      "citation": "Ludewig & Jannach, 'Evaluation of Session-based Recommendation Algorithms', UMUAI 2018.",
      "summary": "Session-based nearest neighbours: it finds past sessions that resemble the one in progress, weighting the current session by position, and scores what those sessions went on to contain. It holds no long-term profile, so it produces recommendations for traffic with no identity attached to it.",
      "stages": "single-stage",
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      "rank": 23,
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      "summary": "One model generates a whole session at once in place of separate retrieval, ranking and reranking stages, and is then aligned to a reward model rather than to logged clicks. Because the slate is decoded jointly, an item's own relevance can be traded against the coherence of the slate, which a pipeline of independently scored items cannot do.",
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    "note": "Two deterministic, hyperparameter-free systems that every release is required to run. They set no endpoint on the scale and are measured like every other entrant — their scores are shown so a reader who knows what these two are can read the rest of the board off them."
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    "alpha": 0.05,
    "n_permutations": 2000,
    "n_pairs_tested_this_release": 150,
    "cells_from_stored_vectors": 30,
    "cells_carried_from_within_run_grids": 504,
    "datasets_with_no_stored_vectors": {
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      ],
      "goodreads-poetry": [
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      ],
      "hm-fashion": [
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      ],
      "kuairand-pure": [
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      ],
      "kuairec": [
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      "lastfm-1k": [
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      ],
      "mind-small": [
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      ],
      "ml-1m": [
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      "ml-32m": [
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      "retailrocket": [
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    "unpairable": [],
    "note": "Pairs are tested from per-user vectors stored in the result files, so two systems need not have run in the same job. Cells marked as carried forward come from a release written before those vectors were stored; they are that release's own tests, not new ones."
  },
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    "by_scenario": {
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        "generative_best": 0.06946922688106064,
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      "cold_items": {
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      "sparse_histories": {
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      "dense_histories": {
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        "generative_best": 0.05283804311934428,
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      "long_tail": {
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      "catalogue_coverage": {
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        "generative_best": 0.34506315600587945,
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      "novelty": {
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      "diversity": {
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        "generative_best": 0.7650801571202693,
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      "multi_objective": {
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        "generative_best": 0.04428467131861211,
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    },
    "generative_systems": [
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      "hstu",
      "netflix_foundation_style",
      "onerec_style"
    ],
    "caveat": "three of the generative entrants are architecture proxies for proprietary systems and one is trained from scratch where the original is adapted from a pre-trained language model; the comparison is between architectures at benchmark scale, not between the companies' production systems"
  },
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    "n_random_rows": 70339,
    "note": "ground truth is a plain average of the reward over the randomly-exposed impressions the system's own slate intersects; it needs no propensity model, which is what makes it ground truth",
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      "licence_url": "https://mengtingwan.github.io/data/goodreads.html"
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      "impressions": false,
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      "impressions": true,
      "licence": "KuaiRand (Gao et al., CIKM 2022) — CC BY 4.0.",
      "licence_url": "https://kuairand.com/"
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      "licence_url": "https://kuairec.com/"
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      "licence_url": "http://ocelma.net/MusicRecommendationDataset/lastfm-1K.html"
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    {
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      "impressions": true,
      "licence": "Microsoft MIND — Microsoft Research License Terms, research use only.",
      "licence_url": "https://msnews.github.io/"
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      "n_inter": 574376,
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      "licence": "GroupLens / MovieLens Terms of Use — research use permitted, redistribution of the dataset not permitted without permission.",
      "licence_url": "https://files.grouplens.org/datasets/movielens/ml-1m-README.txt"
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      "licence": "GroupLens / MovieLens Terms of Use — research use permitted, redistribution of the dataset not permitted without permission.",
      "licence_url": "https://files.grouplens.org/datasets/movielens/ml-32m-README.html"
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    {
      "name": "retailrocket",
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      "licence": "RetailRocket e-commerce dataset — CC BY-NC-SA 4.0.",
      "licence_url": "https://www.kaggle.com/datasets/retailrocket/ecommerce-dataset"
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    "unavailable": {
      "tiger": {
        "amazon-beauty-2023": "no separable ranking stage",
        "goodreads-poetry": "no separable ranking stage",
        "hm-fashion": "no separable ranking stage",
        "kuairand-pure": "no separable ranking stage",
        "kuairec": "no separable ranking stage",
        "lastfm-1k": "no separable ranking stage",
        "mind-small": "no separable ranking stage",
        "ml-1m": "no separable ranking stage",
        "ml-32m": "no separable ranking stage",
        "retailrocket": "no separable ranking stage"
      },
      "plum_style": {
        "amazon-beauty-2023": "no separable ranking stage",
        "goodreads-poetry": "no separable ranking stage",
        "hm-fashion": "no separable ranking stage",
        "kuairand-pure": "no separable ranking stage",
        "kuairec": "no separable ranking stage",
        "lastfm-1k": "no separable ranking stage",
        "mind-small": "no separable ranking stage",
        "ml-1m": "no separable ranking stage",
        "ml-32m": "no separable ranking stage",
        "retailrocket": "no separable ranking stage"
      },
      "onerec_style": {
        "amazon-beauty-2023": "no separable ranking stage",
        "goodreads-poetry": "no separable ranking stage",
        "hm-fashion": "no separable ranking stage",
        "kuairand-pure": "no separable ranking stage",
        "kuairec": "no separable ranking stage",
        "lastfm-1k": "no separable ranking stage",
        "mind-small": "no separable ranking stage",
        "ml-1m": "no separable ranking stage",
        "ml-32m": "no separable ranking stage",
        "retailrocket": "no separable ranking stage"
      },
      "popularity": {
        "amazon-beauty-2023": "no separable ranking stage",
        "goodreads-poetry": "no separable ranking stage",
        "hm-fashion": "no separable ranking stage",
        "kuairand-pure": "no separable ranking stage",
        "kuairec": "no separable ranking stage",
        "lastfm-1k": "no separable ranking stage",
        "mind-small": "no separable ranking stage",
        "ml-1m": "no separable ranking stage",
        "ml-32m": "no separable ranking stage",
        "retailrocket": "no separable ranking stage"
      },
      "itemknn": {
        "amazon-beauty-2023": "no separable ranking stage",
        "goodreads-poetry": "no separable ranking stage",
        "hm-fashion": "no separable ranking stage",
        "kuairand-pure": "no separable ranking stage",
        "kuairec": "no separable ranking stage",
        "lastfm-1k": "no separable ranking stage",
        "mind-small": "no separable ranking stage",
        "ml-1m": "no separable ranking stage",
        "ml-32m": "no separable ranking stage",
        "retailrocket": "no separable ranking stage"
      },
      "recency_pop": {
        "amazon-beauty-2023": "no separable ranking stage",
        "goodreads-poetry": "no separable ranking stage",
        "hm-fashion": "no separable ranking stage",
        "kuairand-pure": "no separable ranking stage",
        "kuairec": "no separable ranking stage",
        "lastfm-1k": "no separable ranking stage",
        "mind-small": "no separable ranking stage",
        "ml-1m": "no separable ranking stage",
        "ml-32m": "no separable ranking stage",
        "retailrocket": "no separable ranking stage"
      },
      "ease": {
        "amazon-beauty-2023": "no separable ranking stage",
        "goodreads-poetry": "no separable ranking stage",
        "kuairand-pure": "no separable ranking stage",
        "kuairec": "no separable ranking stage",
        "mind-small": "no separable ranking stage",
        "ml-1m": "no separable ranking stage",
        "ml-32m": "no separable ranking stage",
        "retailrocket": "no separable ranking stage"
      },
      "ials": {
        "amazon-beauty-2023": "no separable ranking stage",
        "goodreads-poetry": "no separable ranking stage",
        "hm-fashion": "no separable ranking stage",
        "kuairand-pure": "no separable ranking stage",
        "kuairec": "no separable ranking stage",
        "lastfm-1k": "no separable ranking stage",
        "mind-small": "no separable ranking stage",
        "ml-1m": "no separable ranking stage",
        "ml-32m": "no separable ranking stage",
        "retailrocket": "no separable ranking stage"
      },
      "vsknn": {
        "amazon-beauty-2023": "no separable ranking stage",
        "goodreads-poetry": "no separable ranking stage",
        "hm-fashion": "no separable ranking stage",
        "kuairand-pure": "no separable ranking stage",
        "kuairec": "no separable ranking stage",
        "lastfm-1k": "no separable ranking stage",
        "mind-small": "no separable ranking stage",
        "ml-1m": "no separable ranking stage",
        "ml-32m": "no separable ranking stage",
        "retailrocket": "no separable ranking stage"
      },
      "content": {
        "amazon-beauty-2023": "no separable ranking stage",
        "goodreads-poetry": "no separable ranking stage",
        "hm-fashion": "no separable ranking stage",
        "kuairand-pure": "no separable ranking stage",
        "kuairec": "no separable ranking stage",
        "lastfm-1k": "no separable ranking stage",
        "mind-small": "no separable ranking stage",
        "ml-1m": "no separable ranking stage",
        "ml-32m": "no separable ranking stage",
        "retailrocket": "no separable ranking stage"
      },
      "option_full": {
        "amazon-beauty-2023": "failed: OutOfMemoryError('CUDA out of memory. Tried to allocate 22.53 GiB. GPU 0 has a total capacity of 22.06 GiB of which 20.92 GiB is free. Including non-PyTorch memory, this process has 1.13 GiB memory in use. Of the allocated memory 312.26 MiB is allocated by PyTorch, and 531.74 MiB is reserved by PyTorch but unallocated. If reserved but unallocated memory is large try setting PYTORCH_CUDA_ALLOC_CONF=expandable_segments:True to avoid fragmentation.  See documentation for Memory Management  (https://pytorch.org/docs/stable/notes/cuda.html#environment-variables)')",
        "hm-fashion": "failed: OutOfMemoryError('CUDA out of memory. Tried to allocate 45.75 GiB. GPU 0 has a total capacity of 22.06 GiB of which 21.22 GiB is free. Including non-PyTorch memory, this process has 850.00 MiB memory in use. Of the allocated memory 459.53 MiB is allocated by PyTorch, and 78.47 MiB is reserved by PyTorch but unallocated. If reserved but unallocated memory is large try setting PYTORCH_CUDA_ALLOC_CONF=expandable_segments:True to avoid fragmentation.  See documentation for Memory Management  (https://pytorch.org/docs/stable/notes/cuda.html#environment-variables)')"
      },
      "option_rerank": {
        "amazon-beauty-2023": "failed: OutOfMemoryError('CUDA out of memory. Tried to allocate 22.53 GiB. GPU 0 has a total capacity of 22.06 GiB of which 20.92 GiB is free. Including non-PyTorch memory, this process has 1.13 GiB memory in use. Of the allocated memory 309.93 MiB is allocated by PyTorch, and 534.07 MiB is reserved by PyTorch but unallocated. If reserved but unallocated memory is large try setting PYTORCH_CUDA_ALLOC_CONF=expandable_segments:True to avoid fragmentation.  See documentation for Memory Management  (https://pytorch.org/docs/stable/notes/cuda.html#environment-variables)')",
        "hm-fashion": "failed: OutOfMemoryError('CUDA out of memory. Tried to allocate 45.75 GiB. GPU 0 has a total capacity of 22.06 GiB of which 21.13 GiB is free. Including non-PyTorch memory, this process has 948.00 MiB memory in use. Of the allocated memory 457.92 MiB is allocated by PyTorch, and 178.08 MiB is reserved by PyTorch but unallocated. If reserved but unallocated memory is large try setting PYTORCH_CUDA_ALLOC_CONF=expandable_segments:True to avoid fragmentation.  See documentation for Memory Management  (https://pytorch.org/docs/stable/notes/cuda.html#environment-variables)')"
      },
      "option_cascade": {
        "amazon-beauty-2023": "failed: OutOfMemoryError('CUDA out of memory. Tried to allocate 22.53 GiB. GPU 0 has a total capacity of 22.06 GiB of which 20.92 GiB is free. Including non-PyTorch memory, this process has 1.13 GiB memory in use. Of the allocated memory 312.26 MiB is allocated by PyTorch, and 531.74 MiB is reserved by PyTorch but unallocated. If reserved but unallocated memory is large try setting PYTORCH_CUDA_ALLOC_CONF=expandable_segments:True to avoid fragmentation.  See documentation for Memory Management  (https://pytorch.org/docs/stable/notes/cuda.html#environment-variables)')",
        "hm-fashion": "failed: OutOfMemoryError('CUDA out of memory. Tried to allocate 45.75 GiB. GPU 0 has a total capacity of 22.06 GiB of which 21.26 GiB is free. Including non-PyTorch memory, this process has 810.00 MiB memory in use. Of the allocated memory 460.21 MiB is allocated by PyTorch, and 37.79 MiB is reserved by PyTorch but unallocated. If reserved but unallocated memory is large try setting PYTORCH_CUDA_ALLOC_CONF=expandable_segments:True to avoid fragmentation.  See documentation for Memory Management  (https://pytorch.org/docs/stable/notes/cuda.html#environment-variables)')"
      },
      "option_calibrated": {
        "amazon-beauty-2023": "failed: OutOfMemoryError('CUDA out of memory. Tried to allocate 22.53 GiB. GPU 0 has a total capacity of 22.06 GiB of which 20.92 GiB is free. Including non-PyTorch memory, this process has 1.13 GiB memory in use. Of the allocated memory 312.26 MiB is allocated by PyTorch, and 531.74 MiB is reserved by PyTorch but unallocated. If reserved but unallocated memory is large try setting PYTORCH_CUDA_ALLOC_CONF=expandable_segments:True to avoid fragmentation.  See documentation for Memory Management  (https://pytorch.org/docs/stable/notes/cuda.html#environment-variables)')",
        "hm-fashion": "failed: OutOfMemoryError('CUDA out of memory. Tried to allocate 45.75 GiB. GPU 0 has a total capacity of 22.06 GiB of which 21.26 GiB is free. Including non-PyTorch memory, this process has 810.00 MiB memory in use. Of the allocated memory 460.21 MiB is allocated by PyTorch, and 37.79 MiB is reserved by PyTorch but unallocated. If reserved but unallocated memory is large try setting PYTORCH_CUDA_ALLOC_CONF=expandable_segments:True to avoid fragmentation.  See documentation for Memory Management  (https://pytorch.org/docs/stable/notes/cuda.html#environment-variables)')"
      }
    }
  },
  "robustness": {
    "percentile_scores": {
      "bert4rec": 54.999323933147515,
      "content": 32.09641665524021,
      "ease": 65.12161252314421,
      "ease_lambdamart": 48.19264433597034,
      "gru4rec": 48.30959481694781,
      "hstu": 44.87231858555394,
      "ials": 50.635836113777366,
      "itemknn": 57.54152574005523,
      "itemknn_mlp": 66.38943164678466,
      "itemknn_multitask": 68.8247006261713,
      "lightgcn": 60.321493593552475,
      "netflix_foundation_style": 42.465996693937925,
      "onerec_style": 38.417022792022884,
      "option_calibrated": 42.379726754726796,
      "option_cascade": 49.58298101680462,
      "option_full": 45.69283521489406,
      "option_rerank": 36.38548951048954,
      "phoenix_style": 20.484778021542738,
      "plum_style": 54.50579513079518,
      "popularity": 36.275366790072745,
      "recency_pop": 59.414278531925625,
      "sasrec": 60.6967583070525,
      "tiger": 48.88558473117308,
      "twotower_dcnv2": 49.311697289638516,
      "twotower_rankmixer": 47.16570874659114,
      "vsknn": 64.41588776147606,
      "vsknn_gbdt": 59.08343426725783
    },
    "rank_correlation_frozen_vs_live_percentile": 0.9829059829059829,
    "like_for_like": {
      "datasets": [
        "amazon-beauty-2023",
        "goodreads-poetry",
        "kuairand-pure",
        "kuairec",
        "mind-small",
        "ml-1m",
        "ml-32m",
        "retailrocket"
      ],
      "order": [
        "itemknn_multitask",
        "itemknn_mlp",
        "sasrec",
        "ease",
        "vsknn",
        "bert4rec",
        "recency_pop",
        "vsknn_gbdt",
        "lightgcn",
        "itemknn",
        "plum_style",
        "gru4rec",
        "option_cascade",
        "twotower_dcnv2",
        "tiger",
        "hstu",
        "option_full",
        "twotower_rankmixer",
        "ials",
        "ease_lambdamart",
        "option_calibrated",
        "netflix_foundation_style",
        "onerec_style",
        "option_rerank",
        "popularity",
        "content",
        "phoenix_style"
      ],
      "index": {
        "itemknn_multitask": 69.18678830227744,
        "itemknn_mlp": 67.37729684265011,
        "sasrec": 66.1136451863354,
        "ease": 64.51358695652173,
        "vsknn": 63.630790631469985,
        "bert4rec": 60.61455098343684,
        "recency_pop": 60.40301501035196,
        "vsknn_gbdt": 59.96703545548654,
        "lightgcn": 57.926533385093165,
        "itemknn": 56.23369565217391,
        "plum_style": 55.716906055900616,
        "gru4rec": 54.37247670807453,
        "option_cascade": 53.01950698757764,
        "twotower_dcnv2": 52.16755628881988,
        "tiger": 52.023033126293996,
        "hstu": 51.616330227743276,
        "option_full": 51.5875873447205,
        "twotower_rankmixer": 51.281719073498955,
        "ials": 50.99980590062111,
        "ease_lambdamart": 50.875905797101446,
        "option_calibrated": 48.23722179089027,
        "netflix_foundation_style": 44.642145445134574,
        "onerec_style": 40.833753881987576,
        "option_rerank": 38.66409484989648,
        "popularity": 35.24915890269151,
        "content": 35.071800595238095,
        "phoenix_style": 26.042168090062113
      },
      "rank_correlation_with_headline": 0.9792429792429792
    },
    "note": "the headline index scores each measurement against a frozen field; the robustness column scores it against the live one, which depends on no published constant. A high rank correlation means the ordering is a property of the results rather than of the frozen constants"
  },
  "coverage": {
    "bert4rec": [
      "amazon-beauty-2023",
      "goodreads-poetry",
      "hm-fashion",
      "kuairand-pure",
      "kuairec",
      "lastfm-1k",
      "mind-small",
      "ml-1m",
      "ml-32m",
      "retailrocket"
    ],
    "content": [
      "amazon-beauty-2023",
      "goodreads-poetry",
      "hm-fashion",
      "kuairand-pure",
      "kuairec",
      "lastfm-1k",
      "mind-small",
      "ml-1m",
      "ml-32m",
      "retailrocket"
    ],
    "ease": [
      "amazon-beauty-2023",
      "goodreads-poetry",
      "kuairand-pure",
      "kuairec",
      "mind-small",
      "ml-1m",
      "ml-32m",
      "retailrocket"
    ],
    "ease_lambdamart": [
      "amazon-beauty-2023",
      "goodreads-poetry",
      "kuairand-pure",
      "kuairec",
      "mind-small",
      "ml-1m",
      "ml-32m",
      "retailrocket"
    ],
    "gru4rec": [
      "amazon-beauty-2023",
      "goodreads-poetry",
      "hm-fashion",
      "kuairand-pure",
      "kuairec",
      "lastfm-1k",
      "mind-small",
      "ml-1m",
      "ml-32m",
      "retailrocket"
    ],
    "hstu": [
      "amazon-beauty-2023",
      "goodreads-poetry",
      "hm-fashion",
      "kuairand-pure",
      "kuairec",
      "lastfm-1k",
      "mind-small",
      "ml-1m",
      "ml-32m",
      "retailrocket"
    ],
    "ials": [
      "amazon-beauty-2023",
      "goodreads-poetry",
      "hm-fashion",
      "kuairand-pure",
      "kuairec",
      "lastfm-1k",
      "mind-small",
      "ml-1m",
      "ml-32m",
      "retailrocket"
    ],
    "itemknn": [
      "amazon-beauty-2023",
      "goodreads-poetry",
      "hm-fashion",
      "kuairand-pure",
      "kuairec",
      "lastfm-1k",
      "mind-small",
      "ml-1m",
      "ml-32m",
      "retailrocket"
    ],
    "itemknn_mlp": [
      "amazon-beauty-2023",
      "goodreads-poetry",
      "hm-fashion",
      "kuairand-pure",
      "kuairec",
      "lastfm-1k",
      "mind-small",
      "ml-1m",
      "ml-32m",
      "retailrocket"
    ],
    "itemknn_multitask": [
      "amazon-beauty-2023",
      "goodreads-poetry",
      "hm-fashion",
      "kuairand-pure",
      "kuairec",
      "lastfm-1k",
      "mind-small",
      "ml-1m",
      "ml-32m",
      "retailrocket"
    ],
    "lightgcn": [
      "amazon-beauty-2023",
      "goodreads-poetry",
      "hm-fashion",
      "kuairand-pure",
      "kuairec",
      "lastfm-1k",
      "mind-small",
      "ml-1m",
      "ml-32m",
      "retailrocket"
    ],
    "netflix_foundation_style": [
      "amazon-beauty-2023",
      "goodreads-poetry",
      "hm-fashion",
      "kuairand-pure",
      "kuairec",
      "lastfm-1k",
      "mind-small",
      "ml-1m",
      "ml-32m",
      "retailrocket"
    ],
    "onerec_style": [
      "amazon-beauty-2023",
      "goodreads-poetry",
      "hm-fashion",
      "kuairand-pure",
      "kuairec",
      "lastfm-1k",
      "mind-small",
      "ml-1m",
      "ml-32m",
      "retailrocket"
    ],
    "option_calibrated": [
      "amazon-beauty-2023",
      "goodreads-poetry",
      "hm-fashion",
      "kuairand-pure",
      "kuairec",
      "lastfm-1k",
      "mind-small",
      "ml-1m",
      "ml-32m",
      "retailrocket"
    ],
    "option_cascade": [
      "amazon-beauty-2023",
      "goodreads-poetry",
      "hm-fashion",
      "kuairand-pure",
      "kuairec",
      "lastfm-1k",
      "mind-small",
      "ml-1m",
      "ml-32m",
      "retailrocket"
    ],
    "option_full": [
      "amazon-beauty-2023",
      "goodreads-poetry",
      "hm-fashion",
      "kuairand-pure",
      "kuairec",
      "lastfm-1k",
      "mind-small",
      "ml-1m",
      "ml-32m",
      "retailrocket"
    ],
    "option_rerank": [
      "amazon-beauty-2023",
      "goodreads-poetry",
      "hm-fashion",
      "kuairand-pure",
      "kuairec",
      "lastfm-1k",
      "mind-small",
      "ml-1m",
      "ml-32m",
      "retailrocket"
    ],
    "phoenix_style": [
      "amazon-beauty-2023",
      "goodreads-poetry",
      "hm-fashion",
      "kuairand-pure",
      "kuairec",
      "lastfm-1k",
      "mind-small",
      "ml-1m",
      "ml-32m",
      "retailrocket"
    ],
    "plum_style": [
      "amazon-beauty-2023",
      "goodreads-poetry",
      "hm-fashion",
      "kuairand-pure",
      "kuairec",
      "lastfm-1k",
      "mind-small",
      "ml-1m",
      "ml-32m",
      "retailrocket"
    ],
    "popularity": [
      "amazon-beauty-2023",
      "goodreads-poetry",
      "hm-fashion",
      "kuairand-pure",
      "kuairec",
      "lastfm-1k",
      "mind-small",
      "ml-1m",
      "ml-32m",
      "retailrocket"
    ],
    "recency_pop": [
      "amazon-beauty-2023",
      "goodreads-poetry",
      "hm-fashion",
      "kuairand-pure",
      "kuairec",
      "lastfm-1k",
      "mind-small",
      "ml-1m",
      "ml-32m",
      "retailrocket"
    ],
    "sasrec": [
      "amazon-beauty-2023",
      "goodreads-poetry",
      "hm-fashion",
      "kuairand-pure",
      "kuairec",
      "lastfm-1k",
      "mind-small",
      "ml-1m",
      "ml-32m",
      "retailrocket"
    ],
    "tiger": [
      "amazon-beauty-2023",
      "goodreads-poetry",
      "hm-fashion",
      "kuairand-pure",
      "kuairec",
      "lastfm-1k",
      "mind-small",
      "ml-1m",
      "ml-32m",
      "retailrocket"
    ],
    "twotower_dcnv2": [
      "amazon-beauty-2023",
      "goodreads-poetry",
      "hm-fashion",
      "kuairand-pure",
      "kuairec",
      "lastfm-1k",
      "mind-small",
      "ml-1m",
      "ml-32m",
      "retailrocket"
    ],
    "twotower_rankmixer": [
      "amazon-beauty-2023",
      "goodreads-poetry",
      "hm-fashion",
      "kuairand-pure",
      "kuairec",
      "lastfm-1k",
      "mind-small",
      "ml-1m",
      "ml-32m",
      "retailrocket"
    ],
    "vsknn": [
      "amazon-beauty-2023",
      "goodreads-poetry",
      "hm-fashion",
      "kuairand-pure",
      "kuairec",
      "lastfm-1k",
      "mind-small",
      "ml-1m",
      "ml-32m",
      "retailrocket"
    ],
    "vsknn_gbdt": [
      "amazon-beauty-2023",
      "goodreads-poetry",
      "hm-fashion",
      "kuairand-pure",
      "kuairec",
      "lastfm-1k",
      "mind-small",
      "ml-1m",
      "ml-32m",
      "retailrocket"
    ]
  },
  "skipped": {
    "ease": {
      "hm-fashion": "catalogue has 39979 items; this system is not attempted above 25000 by policy",
      "lastfm-1k": "catalogue has 42638 items; this system is not attempted above 25000 by policy"
    },
    "ease_lambdamart": {
      "hm-fashion": "catalogue has 39979 items; this system is not attempted above 25000 by policy",
      "lastfm-1k": "catalogue has 42638 items; this system is not attempted above 25000 by policy"
    }
  },
  "confidence_levels": {
    "official": "Authors' released implementation, run as published.",
    "reference": "Faithful implementation of a fully specified public method.",
    "reproduction": "Our implementation from the paper, using the paper's stated design.",
    "proxy": "Architecture proxy. The target system is proprietary and only partially described; we implement the published mechanism at benchmark scale. Not the production system."
  },
  "caveats": [
    "On the one dataset that inserts randomly-chosen items into real feeds — the only place an unbiased estimate is available — the offline ordering and the unbiased ordering correlate at 0.17 and name different winners. That is a limit on what any offline recommender benchmark, including this one, can tell you.",
    "Public offline datasets are not production environments. Offline relevance is a proxy for user value, and the mapping between them is platform-specific.",
    "Several entrants are architecture proxies for proprietary systems. They implement a published mechanism at benchmark scale and are not those companies' production systems.",
    "No single recommender wins every scenario. The winner changes 5 ways across the scenario boards.",
    "Entrants added after the calibrating release are measured in their own run rather than beside the systems they are ranked against. Every board is unaffected — a score is a percentile in a frozen distribution, not a rank against whoever ran that day — but a head-to-head significance cell exists only where both systems' result files carry per-user vectors. Which cells those are is published in `pairwise_provenance`. Cost and latency use the same instance types across runs, not the same job.",
    "Serving latency is offline batch throughput on the benchmark host, not a production p99. Multi-stage systems additionally build their ranker's features online here, which a deployed pipeline precomputes — so their measured serving cost is an upper bound and the cost gap to single-stage systems is overstated.",
    "Scale is the untested variable: the central claim of the industrial generative systems is a scaling claim this benchmark is too small to test.",
    "The index scores each measurement by its percentile in a frozen, published distribution. That records where a system placed, not by how much: doubling the best cold-start result and beating it by a hair score the same. Raw metric values are published beside every score, and the scenario boards are stated in raw metrics.",
    "This is index version v3.1 and its scores are not comparable to v3.0's. The v3.0 scale rescaled every metric so Popularity read 0 and ItemKNN 100; it was withdrawn before publication because on two of ten datasets Popularity beat ItemKNN, which inverted the scale, and where the two were close a worse result could reach -381. The effect was to flatter ItemKNN by about six places. Under v3.1 nothing is pinned and ItemKNN places 9th."
  ]
}
