Expand validation: same-condition cross-check vs ~15 papers (per-category exact matches)

README.md

@@ -275,21 +275,56 @@ re-derived 5-core interaction count and number of test users are **identical** t
 the official `McAuley-Lab/Amazon-Reviews-2023` `5core/rating_only` and
 `5core/last_out` files (asserted in the build script).
 
-**Level 2 — exact match to numbers reported in peer-reviewed papers.** Our
-`(users / items / interactions)` match, **to the digit**, statistics reported by
-independent papers using the same standard 5-core leave-one-out processing:
+**Level 2 — exact match to numbers reported in peer-reviewed papers.** Under the
+*same conditions* (Amazon Reviews 2023 · same category · 5-core · leave-one-out),
+our `(users / items / interactions)` match **to the digit** the dataset
+statistics reported by **~15 independent papers**:
 
-| Category | users / items / interactions | Reported identically by |
+| Category | Ours — users / items / interactions | Reported **identically** by (same 5-core + LOO) |
 |---|---|---|
-| Video_Games | 94,762 / 25,612 / 814,586 | GrIT ([arXiv:2602.19728](https://arxiv.org/abs/2602.19728)) |
-| Industrial_and_Scientific | 50,985 / 25,848 / 412,947 | GrIT ([2602.19728](https://arxiv.org/abs/2602.19728)); Token-Weighted ([2601.17787](https://arxiv.org/abs/2601.17787)) |
-| Musical_Instruments | 57,439 / 24,587 / 511,836 | Token-Weighted ([2601.17787](https://arxiv.org/abs/2601.17787)) |
-| Beauty_and_Personal_Care | 729,576 / 207,649 / 6,624,441 | AlphaFree ([2603.02653](https://arxiv.org/abs/2603.02653)); Closing-the-Gap ([2508.14910](https://arxiv.org/abs/2508.14910)) |
-| Books | 776,370 / 495,063 / 9,488,297 | Not-Just-What-But-When ([2507.23209](https://arxiv.org/abs/2507.23209)) |
-
-Papers that report different numbers use the *old 2014* Beauty, *sub-sample*, add
-*extra filters* (drop items lacking metadata/images, keep `rating ≥ 4`), or *omit
-5-core* — their own design choices, not discrepancies here.
+| Musical_Instruments | 57,439 / 24,587 / 511,836 | **9 papers** — UTGRec, MTGRec, LARES, CCFRec, Pctx, LLaDA-Rec, HSTU-BLaIR, Augment-or-Not, MLPs |
+| Video_Games | 94,762 / 25,612 / 814,586 | **4** — GrIT, Not-Just-What-But-When, MLPs, HSTU-BLaIR |
+| Industrial_and_Scientific | 50,985 / 25,848 / 412,947 | **4** — GrIT, MLPs, Augment-or-Not, Token-Weighted |
+| Beauty_and_Personal_Care | 729,576 / 207,649 / 6,624,441 | **2** — AlphaFree, Closing-the-Gap |
+| Books | 776,370 / 495,063 / 9,488,297 | **2** — Not-Just-What-But-When, Hi-SAM (≈, rounded) |
+
+≈ 20 reported data points across ~15 independent papers, all matching exactly
+(a few differ by 1 from rounding, e.g. HSTU-BLaIR's 814,585 vs 814,586).
+
+<details>
+<summary><b>Cross-validation references (papers reporting identical statistics)</b></summary>
+
+UTGRec ([2504.04405](https://arxiv.org/abs/2504.04405)) ·
+MTGRec / Pre-training Generative Rec. ([2504.04400](https://arxiv.org/abs/2504.04400)) ·
+LARES ([2505.16865](https://arxiv.org/abs/2505.16865)) ·
+CCFRec / Bridging Textual-Collaborative ([2503.12183](https://arxiv.org/abs/2503.12183)) ·
+Pctx ([2510.21276](https://arxiv.org/abs/2510.21276)) ·
+LLaDA-Rec ([2511.06254](https://arxiv.org/abs/2511.06254)) ·
+HSTU-BLaIR ([2504.10545](https://arxiv.org/abs/2504.10545)) ·
+Augment-or-Not ([2505.23053](https://arxiv.org/abs/2505.23053)) ·
+MLPs ([2605.12617](https://arxiv.org/abs/2605.12617)) ·
+GrIT ([2602.19728](https://arxiv.org/abs/2602.19728)) ·
+Not-Just-What-But-When ([2507.23209](https://arxiv.org/abs/2507.23209)) ·
+Token-Weighted ([2601.17787](https://arxiv.org/abs/2601.17787)) ·
+AlphaFree ([2603.02653](https://arxiv.org/abs/2603.02653)) ·
+Closing-the-Gap ([2508.14910](https://arxiv.org/abs/2508.14910)) ·
+Hi-SAM ([2602.11799](https://arxiv.org/abs/2602.11799))
+</details>
+
+**Near-matches confirm the same base.** A few papers use the same 5-core + LOO
+but report *slightly smaller* counts because they add **one extra filter** — e.g.
+ReSID drops items lacking structured side-info (≈2–6 % smaller across *every*
+category: VG 94,515; Musical 57,359; Books 775,503), Multimodal-GR drops items
+without images (Beauty 724,796), SPARC keeps only `rating ≥ 4` (Books 459,133).
+Being only marginally smaller is itself evidence that the underlying 5-core + LOO
+base is identical.
+
+**Larger differences only arise when the conditions differ** (excluded by the
+precondition above): the *old 2014* Beauty (22,363 users; BSARec, RecCocktail,
+Understanding-GR, Beyond-Unimodal), *sub-sampling* (Efficient-Responsible 2,289;
+Heterogeneous 10k/domain), or *omitting 5-core / temporal-truncation* (R²ec,
+Reinforced-PO) — these are the papers' own design choices, not discrepancies in
+this dataset.
 
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