Cut off — where it appears
Also named here as neighbourhood — the same set of essays touches all of them, so they are one junction rather than several.
A neighbourhood is a hypothesis
Every simulation of this kind stops summing somewhere. The previous phase found that where it stops decides what pattern comes out — so the stopping place is not a detail of the program but a claim about how far a primordium's influence reaches, and it should be written down as one.
A hard edge is not a falloff
The prediction was that cutting the neighbourhood at three spacings would reproduce the pattern truncation had manufactured. It does — if the cut is smooth. A hard cut at the same distance produces no pattern at any width, and the reason is that it is the only one of the three whose neighbour set depends on where the candidate is.
Two shapes, one threshold
Read in the same unit, an exponential falloff and a gaussian one disagree about where the lattice ends by half. The quantity they agree on turns out to be one the previous phase measured for an unrelated reason — and it agrees with a bracket left by a sweep of a completely different parameter.
The fragility belonged to the window
A pattern that exists only because the rule cannot see far was expected to be held together by that cut, and to fall over when nudged. It does — while the cut is a loop bound. Written down as a falloff at the same range, the same rule keeps every run under the same nudge, at a scatter an inverse-cube rule cannot be told from.
Named alongside it
The objects these essays reach for when they reach for this one.
The range of the interactionNeighbourhoodThe placement ruleRepulsionArtefactDivergence angleLattice offsetTruncationDiscretisationEnsembleModel scopeNegative result