Relative genericity for explicit affine collars #
This module connects the boundary-restricted polynomial family of
ExplicitAffineRelativeCollar to the weaker positive-ray general-position interface used by the
finite Stokes theorem.
All facet determinant polynomials remain in the genericity family. Codimension-two minors are required only when the corresponding face is not purely horizontal. Purely horizontal codimension-two faces are handled by a separate endpoint-safety condition, which is the condition to be derived from the two stable endpoint approximations.
The final section packages finite multivariate perturbation on movable parameter orbits and proves that closeness there gives closeness of the reconstructed full assignment while retaining the horizontal boundary literally.
Simultaneous nonvanishing of the complete boundary-restricted polynomial family.
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A single explicit movable assignment at which a restricted genericity value is nonzero proves that the corresponding restricted polynomial is genuinely nonzero. This is the useful geometric form of the nontriviality obligation: collar constructions may provide a local witness rather than an equality proof in a multivariate polynomial ring.
Pointwise geometric witnesses imply nontriviality of the complete finite restricted polynomial family. Different indices may use different movable assignments.
Only nonhorizontal local facets and the retained codimension-two minors need a genuinely movable genericity witness. Horizontal facet determinants are fixed endpoint determinants.
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- NRR.FoxNeuwirthOrderComplex.EquivariantPrismStableRelativeBoundary.ExplicitAffineRelativeCollar.RelativeGenericity.RequiresMovableGenericityWitness hp C (Sum.inr val) = True
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Restrict a full assignment to its movable parameter subtype.
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A horizontal local facet of an endpoint-fixed collar has nonzero determinant because it is literally one of the two supplied stable endpoint facets.
For the endpoint-adjusted collar assignment, horizontal facet genericity is automatic after any movable perturbation.
Geometric witnesses are required only for the nonhorizontal part of the relative genericity family; stable endpoint regularity supplies all horizontal facet witnesses automatically.
Relative genericity gives facet regularity on every explicit top cell.
Relative genericity makes every non-purely-horizontal codimension-two deviation matrix nonsingular.
Safety condition left for the frozen endpoint geometry. It is required only when the ordered codimension-two face determined by the two vanishing barycentric coordinates is purely horizontal.
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A purely horizontal codimension-two point is represented on the proper skeleton of one of the two actual endpoint triangulations, with exactly the same affine coordinate value. This is the geometric compatibility condition needed to transfer stable endpoint transversality to an arbitrary relative collar triangulation.
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Stable endpoint skeleton transversality converts exact horizontal endpoint representation into the positive-ray safety property required by the relative local Stokes theorem.
On a purely horizontal codimension-two face, changing movable parameters does not alter the represented affine value. The two omitted barycentric coordinates vanish, while every retained vertex belongs to a frozen endpoint boundary.
Horizontal positive-ray safety depends only on frozen endpoint values and is therefore preserved by every replacement of the movable parameter orbits.
Nonhorizontal minor regularity plus horizontal endpoint safety gives the exact positive-ray-relative codimension-two avoidance condition.
Relative genericity, horizontal endpoint safety, and origin avoidance give the local positive-ray general-position interface.
The relative genericity package implies the exact cellwise positive-ray Stokes identity.
Finite perturbation on movable parameter orbits #
A finite family of nonzero restricted polynomials admits a simultaneously generic movable assignment arbitrarily close to any prescribed movable assignment.
Closeness on movable parameter orbits gives closeness of the reconstructed full assignments; frozen horizontal parameters agree exactly.
Quantitative origin-avoidance retention #
Replacing movable parameters by the restriction of the base assignment reconstructs the base assignment exactly.
The full parameter represented by one local vertex coordinate.
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A coordinate witness for a uniform lower bound on every local affine value.
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Coordinatewise closeness of full assignments bounds each coordinate of each local affine interpolation.
A coordinate norm margin decreases by at most the assignment perturbation size.
A positive coordinate norm margin implies local origin avoidance.
Cellwise origin avoidance on a finite relative collar automatically has a uniform positive coordinate margin. Compactness gives a positive norm minimum on each affine simplex; finiteness of the cell family gives one common minimum, and the finite-product sup norm is attained in a coordinate.
Output of a small boundary-relative generic perturbation retaining half of a supplied origin margin.
- move : Parameters.MovableParameter hp C → ℝ
The selected values of the movable real coordinates.
- closeToBase : EquivariantPrismGenericPerturbation.AssignmentClose (Parameters.replaceMovable hp C base self.move) base (m / 2)
- relativeGeneric : IsRelativeGeneric hp C base self.move
- retainedMargin : LocalAffineCoordinateNormMargin hp C (Parameters.replaceMovable hp C base self.move) (m / 2)
- avoidsOrigin (q : C.Cell) : (Polynomials.localVertexMap hp C (Parameters.replaceMovable hp C base self.move) q).AvoidsOrigin
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Simultaneously make all nontrivial boundary-relative genericity polynomials nonzero while retaining half of a positive affine origin margin.