What k-NN Is and Is Not - k-NN and Boundaries

The finale separates exact neighbor mechanics from broader modeling choices. It keeps the table and finite region map visible while stating the boundary.

highlighted = computed this step

What is exact

The distances, neighbor order, and majority vote are exact for the shown training set. The query (1, 1) receives class A.

\text{query }(1, 1)\mapsto A

What this surface stops at

The finite region map is a checked grid of integer points. A different k or a denser grid would need its own displayed recomputation.

\text{finite grid, exact vote}

Summary

This is not accuracy, not a choice-of-k rule, and no claim of generalization; it pins nearest-neighbor mechanics on toy data.

\text{toy-data nearest-neighbor mechanics only}