Result · HARD-GEOMETRIC-EMPIRICAL-PIECEWISE-CONSTANT
Hard empirical objectives have flat regions
Proved herepublication: internal
Meaning
Moving a boundary without crossing a sample point leaves its labels and hard objective unchanged.
Statement
For hard affine/Voronoi parameterizations, finite empirical labels and cell moments remain unchanged until a training row crosses a boundary; ordinary gradient is therefore zero almost everywhere.
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Proof
S3. Hard empirical geometric objective is piecewise constant
For a hard affine/Voronoi quantizer parameterized by continuous generators/hyperplanes, the finite empirical objective is piecewise constant in those parameters: until a training row crosses a boundary, labels and cell moments do not change.
Therefore ordinary gradient descent on the hard finite objective is zero almost everywhere and is not a useful generic solver.