claimroutine

Polynomials vanish rarely on loci

Claim·§8.2 A complete grid with generic positions·inside lemGeneric complete grid with independent coordinates

Statement (paper)

On a side whose locus is the plane, for each fixed degree bound DD there is a bD>0b_D>0 such that every nonzero polynomial of degree at most DD, even with coefficients depending on nn, vanishes at at most tn1−bDt_n^{1-b_D} pruned vertices on a large set of indices. On a curve side, a nonzero polynomial of degree DD in the selected zz-coordinate has at most DD zeros among the vertices.

In plain English

On a plane-locus side, for each degree bound DD there is bD>0b_D>0 such that any nonzero polynomial of degree at most DD, even with nn-dependent coefficients, vanishes at no more than tn1−bDt_n^{1-b_D} pruned vertices on a large set of indices. On a curve-locus side, a nonzero polynomial of degree DD in the selected zz-coordinate has at most DD zeros among the vertices.

Why it's here

This supplies the quantitative genericity input for choosing the grid: a nonzero polynomial test can kill only a small fraction of vertices, a power saving on planes and a bounded number on curves. Later claims use it inductively to pick grid vertices whose selected coordinates avoid every given vanishing condition, which gives algebraic independence over B0B_0. The plane bound comes from the minimality of the locus, while on curves it is simply the degree bound for a one-variable polynomial.
Classified routine:
Follows from the minimality of the plane locus, i.e. vertices not concentrating on curves of bounded degree, plus the fact that a one-variable polynomial of degree D has at most D roots. This is a standard genericity/bookkeeping step inside the generic-grid construction.

Uses

Nothing else in the paper

Used by

Sources

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§8.2 A complete grid with generic positions
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sections/07-algebra.tex:216
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