Conforming fan maps on adaptive midpoint tiles #
Each first-safe adaptive triangle has finitely many resolved vertices on its boundary. Coning successive boundary vertices to the positive barycentric center gives a locally finite family of parametrized triangles in the open subpolyhedron. This file constructs those maps before proving the global face-to-face intersection theorem.
A preconnected subset of a polygonal circle which avoids every polygon vertex cannot pass from one open edge to another. Thus meeting one edge forces the whole set to lie in that edge. This is the elementary component fact used to compare hanging-edge subdivisions.
The source point of a geometric fan vertex in the refined realization carrying its tile.
Equations
- K.adaptiveFanVertexSource U hU f p = (K.safeSubdivision f.fst.fst).homeo.symm ↑p
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The distinguished cone-center vertex of a fan triangle.
Equations
- K.adaptiveFanCenterVertex U hU f = ⟨K.adaptiveFaceCenter U f.fst, ⋯⟩
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The first base vertex of a fan triangle.
Equations
- K.adaptiveFanFirstVertex U hU f = ⟨K.adaptiveEdgeIntervalFirst U hU f.fst f.snd.fst f.snd.snd, ⋯⟩
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The second base vertex of a fan triangle.
Equations
- K.adaptiveFanSecondVertex U hU f = ⟨K.adaptiveEdgeIntervalSecond U hU f.fst f.snd.fst f.snd.snd, ⋯⟩
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The three distinguished fan weights sum to one.
The canonical interval parametrization of the resolved base of a fan triangle.
Equations
- K.adaptiveFanBaseSimplexPath U hU f r = ⟨(AffineMap.lineMap ⇑(stdSimplex.vertex (K.adaptiveFanFirstVertex U hU f)) ⇑(stdSimplex.vertex (K.adaptiveFanSecondVertex U hU f))) ↑r, ⋯⟩
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The normalized parameter of the boundary point obtained by radially projecting a noncenter fan point away from the cone center.
Equations
- K.adaptiveFanNormalizedBaseParameter U hU f x hxCenter = ⟨↑x (K.adaptiveFanSecondVertex U hU f) / (1 - ↑x (K.adaptiveFanCenterVertex U hU f)), ⋯⟩
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The radial projection of a noncenter fan point to its resolved base interval.
Equations
- K.adaptiveFanNormalizedBasePoint U hU f x hxCenter = K.adaptiveFanBaseSimplexPath U hU f (K.adaptiveFanNormalizedBaseParameter U hU f x hxCenter)
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Barycentric combination of a fan face's three geometric vertices, formed in the faithful refined realization before transporting back to the original complex.
Equations
- K.adaptiveFanSourcePoint U hU f x = ⟨fun (v : (K.safeSubdivision f.fst.fst).refined.Vertex) => ∑ p : ↥(K.adaptiveFanFaceVertices U hU f), x p * ↑(K.adaptiveFanVertexSource U hU f p) v, ⋯⟩
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The canonical line segment between two barycentric points of one fan face.
Equations
- K.adaptiveFanSimplexLineMap U hU f x y r = ⟨(AffineMap.lineMap ↑x ↑y) ↑r, ⋯⟩
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Pulling an edge point back through the faithful subdivision gives zero in every coordinate outside that edge.
The coordinate opposite a fan triangle's base edge is exactly one third of its cone-center weight.
The cone-center contribution is a lower bound for every barycentric coordinate of a fan point in its ambient refined face. At the coordinate opposite the fan base this bound is an equality.
A noncenter fan point is the affine combination of the cone center and its normalized radial projection to the base.
A vertex of a triangular intrinsic face outside one cyclic edge is the opposite vertex.
The three cyclic edges of a triangular level face are pairwise distinct.
Earlier resolved intervals on one ordered tile edge end no later than later intervals begin.
Zero cone-center weight places a fan source point on its resolved base edge.
When the cone-center weight vanishes, the two ordered base weights sum to one.
The three pulled-back vertices of a fan face are affinely independent. The two boundary vertices lie in the affine coordinate hyperplane opposite their common edge, while the positive center does not.
The affine combination map is injective when its source points are affinely independent.
The coordinate function underlying an adaptive fan source point.
The standard simplex parametrizing one adaptive fan face.
Equations
- K.adaptiveFanSimplex U hU f = stdSimplex ℝ ↥(K.adaptiveFanFaceVertices U hU f)
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The coordinate-valued source-point map used for injectivity.
Equations
- K.adaptiveFanSourcePointVal U hU f x = ↑(K.adaptiveFanSourcePoint U hU f x)
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One parametrized fan triangle in the open subspace.
Equations
- K.adaptiveFanFaceMap U hU f x = ⟨(K.safeSubdivision f.fst.fst).homeo (K.adaptiveFanSourcePoint U hU f x), ⋯⟩
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A fan parametrization sends each abstract vertex to its declared geometric point.
Within one adaptive tile, a geometric point determines its cone-center weight. This is the minimum-coordinate characterization of radial coordinates in a triangle.
After removing the common cone-center contribution, equal points in one tile have equal radial projections to the tile boundary. The shared tile is explicit to avoid dependent transport through the two interval types.
The geometric interval path along a resolved fan base.
Equations
- K.adaptiveFanBasePath U hU f = K.adaptiveFanFaceMap U hU f ∘ K.adaptiveFanBaseSimplexPath U hU f
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In refined barycentric coordinates, the canonical fan-base path is the line segment between the two pulled-back endpoint vertices.
Faithfulness of the iterated subdivision makes every geometric fan-base path the literal ambient affine segment between its two declared endpoints.
A zero-center barycentric point is determined by its second base weight.
Every zero-center barycentric point has its declared second base weight as the canonical base-path parameter.
The adaptive face chart takes a transported cyclic edge to the matching standard edge.
The adaptive tile barycenter is an interior point in the standard plane chart.
The inverse adaptive face chart is given by the explicit affine inverse in refined barycentric coordinates.
A radial segment in the plane tile chart pulls back to the corresponding affine segment in the refined barycentric face.
The adaptive face chart carries the relative boundary of a tile into the standard polygonal triangle boundary.
A point which an adaptive face chart sends to a standard triangle corner is one of that tile's collected boundary marks.
Along a fan base, the ambient edge parameter is the convex combination of the two endpoint parameters with the two remaining simplex weights.
Every point of a resolved adaptive edge is represented by one of its consecutive fan-base paths.
The fan triangles over one adaptive tile cover the whole closed tile.
A point in the relative interior of a resolved fan base is not one of the tile's collected boundary marks.
Relative-interior points of resolved bases in one adaptive tile can agree only when the bases lie on the same cyclic tile edge.
Relative interiors of two consecutive-list intervals on the same tile edge are disjoint unless the interval indices are equal.
Positive weight at the cone center places a fan point in the relative interior of its adaptive tile.
A point common to fan triangles from distinct adaptive tiles has zero cone-center weight in the first triangle.
At a common nonvertex point, the base edge belonging to the later adaptive tile lies in the earlier tile.
If interiors of two resolved fan bases meet and the second tile is no earlier in the adaptive hierarchy, then the entire second resolved interval lies in the first base edge.
Two resolved fan intervals whose relative interiors meet have the same geometric endpoints, possibly with opposite order.
Extended coordinates of a fan triangle are the sum of its three vertex-weight spikes.
Radial projection to the fan base recovers the original global coordinates after restoring the cone-center weight.
Cross-tile interior overlap is face-to-face not only as a set: the two affine parametrizations assign the same global barycentric coordinates.
A zero-center fan point which is not in the relative interior of its base is one of the two declared base vertices, both geometrically and in extended barycentric coordinates.
The resolved fan face assembled from a tile, edge, and interval.
Instances For
The simplex parametrizing a resolved fan face.
Equations
- K.adaptiveFanFaceSimplex U hU t i a = stdSimplex ℝ ↥(K.adaptiveFanFaceVertices U hU (K.adaptiveFanFace U hU t i a))
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Fan triangles belonging to distinct adaptive tiles assign the same global barycentric coordinates to every common geometric point. Interior points use the resolved-interval compatibility theorem; endpoint points are the common boundary marks collected by both tiles.
All adaptive fan faces use one global barycentric coordinate system on their overlaps.
In one adaptive tile, equal global coordinates have equal pulled-back barycentric sums and hence equal images.
The center of one adaptive tile is not a fan vertex of a distinct tile.
On a fan base, the parametrization is the literal weighted sum of its declared geometric vertices.
Across distinct adaptive tiles, equal global coordinates describe the same point on their common resolved boundary.
Equal global barycentric coordinates are sufficient for equality of adaptive fan images.
The fan-triangle family is locally finite because it has finitely many faces over each adaptive tile and the adaptive tile family is locally finite.