claimroutineinferred_dep

Logarithmic residues force constant Y

Shows YY is constant on ZZ, so Y=1Y=1 on CC
puts the curve in the fiber Y=1Y=1
Claim·§2.2 The curve inequality·inside propCurve inequality for weighted degree

Statement (paper)

On the persistent component ZZ, the function YY is constant. In particular Y=1Y=1 on C∘C^\circ, and hence on CC by density. When some positive coordinate direction is nontangent to ZZ, one has dXi=dY/YdX_i=dY/Y on ZZ for the largest such index ii, and this forces YY (and XiX_i) to be constant on ZZ.

In plain English

On the persistent component ZZ the function YY is constant, so Y=1Y=1 on C∘C^\circ and hence on CC by density. If some positive coordinate direction is nontangent to ZZ, then dXi=dY/YdX_i=dY/Y on ZZ for the largest such index ii, which forces YY and XiX_i to be constant on ZZ.

Why it's here

This shows that the persistent component lies inside the affine fiber Y=1Y=1, which lets the next claim work with a fiber polynomial there. The idea is to use the normal-basis weight bound from the persistent-component claim together with the separated-weights choice. These rule out every index pattern except the one where the largest nontangent direction gives dXi=dY/YdX_i=dY/Y, and that relation forces YY to be constant.
Classified routine:
The index-pattern reduction follows from the earlier persistent-component normal-basis bound and separated-weights choice. The final step uses the standard residue obstruction: an exact differential cannot equal dY/Y for a nonconstant rational function Y on an algebraic curve.

Sources

PaperOpen
Section
§2.2 The curve inequality
Page
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Label
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Line
sections/interpolation.tex:327
Leannot aligned

Phase 2 aligns this node to a Lean declaration.

Friction

  • info
    inferred_dep
    outline: "Logarithmic residues force constant Y" rests on claim-geom-curve-inequality-3
  • info
    inferred_dep
    outline: "Logarithmic residues force constant Y" rests on claim-geom-interpolation-1