Corrections & changes

How this log works

Entries are checked against their sources as part of ongoing editorial review, and anything substantively wrong gets fixed and recorded here. Typos and formatting don't make the log; wrong claims do. Each item shows the old wording, the new wording, and the date it changed. If you spot an error, report it — confirmed corrections are logged with credit if you want it.

July 18, 2026

ROC-AUC — wrong lower bound. Was: "One number, between 0.5 (coin flip) and 1.0 (perfect)." Now: "1.0 is perfect, 0.5 is a coin flip, and below 0.5 means the model is worse than chance — its scores are systematically inverted, and flipping them would do better." AUC's floor is 0.0, not 0.5. A classifier can rank worse than chance.

Retrieval-Augmented Generation — clarified what the founding paper actually describes. Was: the Lewis et al. (2020) citation read simply "the paper that named it." Now: it adds that the paper describes a different system to today's — a DPR retriever and a BART generator fine-tuned jointly, not a frozen model with retrieved text in the prompt. The name survived; the architecture didn't.

July 17, 2026

Prompt Engineering — a "first" the cited paper itself contradicts. Was: in-context learning "was first demonstrated at scale" by GPT-3. Now: GPT-3's contribution was few-shot in-context learning at scale, and the name — its own paper credits GPT-2 (Radford et al., 2019) with demonstrating zero-shot task transfer.

Perplexity — cited a problem, omitted the same paper's answer. Was: Ouyang et al. (2022) cited for "the alignment tax; usefulness up, perplexity worse." Now: the note adds that the paper largely resolves the tax it names — mixing pretraining gradients into RLHF (PPO-ptx) removes most of the regression.

July 16, 2026

k-Nearest Neighbours — a folk law stated without its condition. Was: "As dimensions grow, distances concentrate: the ratio between the nearest and farthest neighbour tends toward 1" — stated as unconditional, and repeated in the summary card ("Breaks on — high dimensions, where distances concentrate"). Now: Beyer et al.'s result carries a condition close to i.i.d. dimensions, and Durrant & Kabán proved the converse — distances don't concentrate at any dimensionality when the relevant dimensions grow with the total. The enemy is irrelevance, not dimension. Corrected in the depth text, the summary card, and the source note.

July 15, 2026

Word2Vec — the doctor-nurse analogy is an artifact. Was: "the same geometry that gives you king − man + woman ≈ queen gives you doctor − man + woman ≈ nurse." Now: Nissim et al. (2020) showed the analogy returns doctor unless the evaluation forbids repeating input words — the same hidden constraint that manufactures the queen result. The entry keeps what survives: bias in embeddings is real; the analogies were never the evidence for it.

July 14, 2026

Scaling Laws — deleted a refuted explanation. Was: the entry repeated Hoffmann et al.'s suggestion that the Kaplan/Chinchilla discrepancy came from learning-rate schedules — "a difference in the learning-rate schedule turned out to matter enormously." Now: the claim is gone, not footnoted. Porian et al. (2024) traced the gap to FLOP counting, warmup length, and optimizer tuning instead.

July 13, 2026

Citation years — preprint dates replaced with published dates. Was: several entries cited papers by their arXiv year — Holtzman et al. as 2019, Bahdanau et al. as 2014, He et al.'s ResNet paper as 2015, LoRA as 2021, the ViT paper as 2020, among others. Now: all cite the published year and venue — Holtzman is ICLR 2020, Bahdanau is ICLR 2015, ResNet is CVPR 2016, LoRA is ICLR 2022, ViT is ICLR 2021. House rule going forward: the published version is the citation.

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Site fixes

July 18 — reading progress bar extended to articles. The thin green bar that tracks reading position existed on concept pages but not on the long-form articles and blog posts — the pages that needed it most. Found while testing on a phone; now on every long-form page.

July 18 — tables scroll on mobile. Some comparison tables in articles overflowed the screen on phones with no way to reach the right-hand columns. All tables now scroll horizontally.

July 17 — search understands abbreviations. Typing "knn", "svm", "vae", "mcp", "ner" or similar into search returned nothing, because search matched titles ("K-Nearest Neighbours") but not the short names people actually type. Found while testing on a phone; search now matches both.