Decision surfaces using NN "opposing pairs"

This research was a fusion of two observations:

• viability envelopes often tend to have relatively low curvature surfaces
• a flat decision surface section can be often cheaply captured using two opposite-class samples facing each other, in close proximity; in fact a planar surface can be captured with exactly just two samples, as seen in the upper-left figure (upper-middle figure is just a close-up of the single pair, the yellow and magenta points)

To the side are some attempts at capturing various decision surface shapes using this method. The green and red dots represent the samples and their class membership (green = in, red = out); the colour of background indicates the predicted class based on the NN pairs. If you look closely you can see the decision surfaces are not perfectly captured, with a few samples/points lying in the wrong coloured regions.