Ablation — the ladder
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The organ that was taken away
Every observable this site has is read off an arrangement that was finished before the reading began, and the last phase showed what that costs. So remove one primordium from a settled stem and place the next one against what is left. The rule has to answer. The rival account cannot, because in it no organ's position was ever computed from its neighbours.
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The experiment this site can specify
For eight phases the outstanding item has been a survey — photographs, a protractor, hundreds of specimens — and it has not been done. The intervention is a different kind of ask, and a cheaper one: a needle, one apex, and a yes-or-no per ablation. Here is what it would cost, what it would settle, and the four ways it could come out.
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A rule that cannot heal a hole
The placement rule corrects itself against a displacement — that is what the lag-one correlation of −0.6 has been saying for three phases. It does not correct itself against a deletion. Which organ is removed decides whether the stem is back on its lattice in twenty-four organs or never, and the boundary between the two is sharp, reproducible and in the middle of the front.