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The first chip identifies the source of the statement or construction; the second identifies the source of its local proof or verification.
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These labels describe origin, not correctness: citations and verification chips remain separate evidence.
Adaptive finite-element methods — Examples
1 · Prerequisites
- Absolute and Conditional Convergence; Rearrangement; Products
- Adaptive finite-element methods
- Areas of Elementary Plane Figures
- Binary Operations, Monoids, Groups and Subgroups
- Céa and Aubin–Nitsche error estimates
- Compactness
- Compactness in Metric Spaces
- Completeness, Completion, and Uniform Continuity
- Complex Lp Spaces and Test-Function Conventions
- Construction of the Natural Numbers
- Construction of the Real Numbers via Cauchy Sequences
- Construction of the Real Numbers via Dedekind Cuts
- Continuity, IVT, EVT, and Uniform Continuity
- Cosets, Index and Lagrange's Theorem
- Countability and Uncountability
- Countability Axioms and Cardinal Functions
- Density Separability and Convolution in Lᵖ
- Determinants of Matrices over a Commutative Ring
- Distributions Test Functions and Differentiation
- Divisibility, Euclidean Domains, Principal Ideal Domains and Unique Factorisation
- Dual Spaces, Bilinear and Quadratic Forms, and Sylvester's Law of Inertia
- Euclidean Surface Measure, Divergence, and Green Identities
- Filters and Ultrafilters
- Finite Counting, Factorials and Binomial Coefficients
- Finite-element meshes and interpolation
- Foundations of the Real Numbers for Analysis
- Fubini and Change of Variables
- Gaussian Elimination, Elementary Matrices and Reduced Row Echelon Form
- Group Actions, Orbits, Stabilisers and Cayley's Theorem
- Ideals, Quotient Rings and the Isomorphism Theorems for Rings
- Inner Product Spaces, Gram-Schmidt, Projections and Adjoints
- Lax--Milgram and Weak Elliptic Solutions
- Lebesgue Measure on Euclidean Space
- Limits of Real Functions
- limsup, liminf, and Subsequential Limits
- Linear Independence, Bases and Dimension
- Linear Transformations, Rank-Nullity and Quotient Spaces
- Matrices, the Matrix of a Linear Map, and Change of Basis
- Measurable Functions and Simple Approximation
- Measures and Their Basic Properties
- Metric Spaces
- Mixed Partials, Taylor Formulae, and Extrema
- Modes of Convergence Egorov and Lusin
- Monotone Functions, Discontinuities, and Continuity Sets
- Monotone Sequences, Bolzano-Weierstrass, and Cauchy Completeness
- Normal Subgroups and Quotient Groups
- Order, Zorn's Lemma, and the Axiom of Choice
- Outer Measure and the Caratheodory Extension Theorem
- Pointwise Extended-Real Function Products
- Polynomial Rings, the Division Algorithm and Roots
- Power Series and Real-Analytic Functions
- Product Measures and the Fubini Tonelli Theorems
- Properties of the Integral and the Working FTC
- Relations, Functions, and Quotients
- Rings, Subrings, Integral Domains and Fields
- Rⁿ as a Normed Space; Vector-Valued Functions
- Roots, Rational Powers, and Classical Inequalities
- Schwartz Space and the Plancherel Theorem
- Separation Axioms: the Hierarchy
- Sequences and Limits
- Sequences and Series of Functions; Uniform Convergence
- Series: Convergence and the Nonnegative Tests
- Sigma Algebras and Borel Sets
- Simple Field Extensions and the Construction of the Complex Numbers
- Smooth Approximation and Sobolev Extension
- Smooth Manifolds and Smooth Maps
- Smooth Partitions of Unity and Exhaustions
- Sobolev Poincare and Morrey Inequalities
- Subspaces, Products, and Quotients
- Suprema and Infima
- Symmetric Groups, Cycle Decomposition and the Sign Homomorphism
- Tangent Cotangent and the Differential
- The Cantor Set, Baire Category, and Measure Zero in ℝ
- The Derivative and the Mean Value Theorems
- The Exponential Function
- The Inverse and Implicit Function Theorems
- The Lebesgue and Riemann Integrals Compared
- The Lebesgue Integral and the Convergence Theorems
- The Logarithm and General Powers
- The Lᵖ Spaces Holder Minkowski and Riesz Fischer
- The Maximal Function and Lebesgue Differentiation
- The Riemann Integral in Rᵐ and Jordan Content
- The Riemann Integral: Definition and Integrability
- The Topology of Euclidean Space
- The Total Derivative in ℝᵐ → ℝⁿ
- The ZFC Axioms and the Basic Set Constructions
- Topological Spaces and Continuity
- Topology of ℝ
- Triangularisation, Generalised Eigenspaces and Jordan Canonical Form
- Vector Spaces, Linear Subspaces, Span and Direct Sums
- Weak Derivatives and Sobolev Spaces
2 · Summary
These finite checks demonstrate the exact descending-prefix bulk rule, P0 data-oscillation projection on a reference triangle, nonconstant conormal-flux oscillation across a coefficient interface, and failure of the stated sufficient small-mesh inequality for a prescribed convection constant. Each verification uses the definitions and hypotheses on adaptive-finite-element-methods. The coefficient and convection examples do not assert general convergence or failure of convergence.
3 · Logical flowchart
4 · Definitions, theorems and proofs
None yet.
5 · Examples, counterexamples and false statements
A coefficient jump creates nonzero edge-flux oscillation
Example
Assume Countable Choice for the cited Sobolev/L2 interface.
Let be shared by and . Set , , and . On each triangle is positive and Lipschitz; its traces differ on .
Facts & Assumptions
Countable Choice is the background assumption in the cited Sobolev and suppliers (The Axiom of Countable Choice ()).
Given: Countable Choice, The piecewise-Lipschitz coefficient interface and projected edge flux oscillation of Residual indicators and data oscillation for P1 AFEM.
For a scalar diffusion coefficient, the outward conormal flux on a side is ; edge oscillation is the squared distance of the outward flux sum from its edge mean (Residual indicators and data oscillation for P1 AFEM).
Verification
The gradient is . The outward normals on are and , so the sum of outward conormal fluxes is . Its edge mean on is .
Since , Thus the coefficient interface creates a nonzero projected edge contribution. No general reliability or complexity assertion for this coefficient model follows from the example.
Finite check
The edge integral is the elementary variance of on , equal to .
A coarse mesh can miss the convection smallness condition
Example
Assume Countable Choice for the cited Sobolev/L2 interface.
Fix a positive mesh diameter , exponent , and a stipulated positive dual-pickup constant . The sufficient small-mesh parameter in Quasi-orthogonality for constant convection on a fine initial mesh is .
Facts & Assumptions
Countable Choice is the background assumption in the cited Sobolev and suppliers (The Axiom of Countable Choice ()).
Given: Countable Choice, A prescribed mesh scale , , , and a constant divergence-free vector .
The nonsymmetric quasi-orthogonality estimate assumes (Quasi-orthogonality for constant convection on a fine initial mesh).
Verification
Choose any unit vector and set . This is constant and divergence-free, and direct substitution gives .
The strict sufficient condition therefore fails on this prescribed mesh. This only shows that the stated sufficient estimate cannot be invoked from its hypotheses; it does not imply failure of convergence or of the PDE solution.
Finite check
The substitution is exact: .
A deterministic Dörfler mark on three cells
Example
Take squared cell indicators in the stated identifier order and .
Facts & Assumptions
Given: Three nonnegative squared indicators and the deterministic prefix rule of Dorfler marking and conforming newest-vertex refinement.
Dörfler marking selects the shortest descending-value prefix whose sum reaches the declared fraction of the total (Dorfler marking and conforming newest-vertex refinement).
Verification
The total is , so the threshold is . The sorted descending prefix sums are .
The first prefix already has sum , while the empty prefix has sum . Thus the unique minimal mark is the first cell, regardless of the later tie rule.
Finite check
The three prefixes are exactly , , and with sums ; the first threshold-crossing prefix has cardinality one.
Projected data oscillation on a reference triangle
Example
Assume Countable Choice for the cited Sobolev/L2 interface.
Let , let , and mark this single cell with . Use the uniform three-generation refinement, any estimator marking fraction, and a per-call budget sufficient for completion.
Facts & Assumptions
Countable Choice is the background assumption in the cited Sobolev and suppliers (The Axiom of Countable Choice ()).
Given: Countable Choice, The P0 cell oscillation and the three-generation refinement rule.
Cell oscillation is (Residual indicators and data oscillation for P1 AFEM).
The marked triangle's edge midpoints and the midpoint on its median occur in the three-generation NVB refinement (Shape regularity and local reduction under 2D newest-vertex bisection).
The Dörfler-marked three-generation refinement reduces oscillation by at least the factor (Data oscillation reduction under three-generation refinement).
Verification
The triangle has area , while the subtriangle where has area , so . Therefore . Since , the initial oscillation square is .
The region is the corner triangle whose other two vertices are the midpoints of the coordinate-axis edges. By [F2] its boundary is a union of refined edges; each refined leaf lies wholly in this region or its complement. Thus is constant on every child, every child P0 projection is exact, and the refined oscillation is zero. This verifies the strict reduction and agrees with [F3], which gives at .
Finite check
The parent mean is and its variance integral is ; the child partition aligns with the indicator boundary, so each child variance is zero.