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P = previous harvest model | A = additions
S = subtractions | File__Graph Math.png 
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A = Diff (H → P) | The additions are the triples that are in the new harvest when the old harvest triples are removed. |
S = Diff (P → H) | The subtractions are the triples that are in the old harvest when the new harvest is removed. |
P = V – S |
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