Reference set thinning for the k-nearest neighbor decision rule
Bibliographic record
Abstract
The k-nearest neighbor decision rule (or k-NNR) is used to classify a point in d-space according to the dominant class among its k nearest neighbors in some reference set (in which each point has a known class). It is useful to find a small subset S' of S that can be used as the reference set instead. If the k-NNR always makes the same decision using either S or S' as the reference set, then S' is called an exact thinning of S for the k-NNR. We show that such an exact thinning can be determined easily from the k-Delaunay graph of S (which is dual to the order-k Voronoi diagram of S). This graph "encodes" a particular subset of S that must be included within any exact thinning for the k-NNR, and it also provides information on how this subset can be augmented into an exact thinning (although perhaps not a minimum one). In addition, we investigate how the k-Gabriel graph (which is a subgraph of the k-Delaunay graph) can be used to derive an inexact thinning of S that performs well in practice for the k-NNR. It is advantageous to use the k-Gabriel graph instead of the k-Delaunay graph, because the k-Gabriel graph is smaller and much easier to compute from the point set S.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.005 | 0.018 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.004 |
| Open science | 0.003 | 0.002 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".