Files
ConformalLabpp/doc/math/references.md
Tarik Moussa 582eb46efa fix(citations): systematic audit — 6 corrections in references.md
Findings from full citation audit of all 34 references.md entries:

CRITICAL:
- Knöppel et al. 2015 "Stripe Patterns": arXiv 1502.06686 was a completely
  different paper (Data-Driven Shape Analysis by Xu et al.) — removed from
  papers/. Correct DOI is 10.1145/2767000, not 10.1145/2766890. No arXiv
  preprint exists for this paper.

ERRORS:
- Born, Bücking, Springborn: published 2017 in DCG 57(2) pp. 305–317
  (DOI 10.1007/s00454-016-9854-7); arXiv 2015 was preprint only
- Bobenko, Mercat, Schmies: short title; full title is
  "Conformal Structures and Period Matrices of Polyhedral Surfaces";
  editors Bobenko & Klein (not generic "Computational Approach" book ref);
  pp. 213–226, DOI 10.1007/978-3-642-17413-1_7

COMPLETIONS (missing vol/pages added):
- Pinkall, Polthier 1993: vol. 2(1), pp. 15–36, DOI added
- Bobenko, Springborn 2004: Trans. AMS 356(2), pp. 659–689, arXiv added
- Luo 2004: Commun. Contemp. Math. 6(5), pp. 765–780, DOI + arXiv added

Verified  (no changes needed, 28/34 entries):
Sechelmann 2016, Springborn 2020/2008, Ushijima 2006, Bowers-Stephenson 2004,
Glickenstein 2011, BPS 2015, Schläfli 1858, Erickson-Whittlesey 2005,
Bobenko-Springborn 2007, Desbrun-Kanso-Tong 2006, Soliman et al. 2018,
all Bobenko-Lutz papers, Lutz 2023/2024, Bowers-Bowers-Lutz 2026,
Alexa-Wardetzky 2011, Bunge et al. 2020, de Goes et al. 2020,
Gillespie-Springborn-Crane 2021, Sharp-Soliman-Crane 2019, Farkas-Kra,
Siegel, Bobenko-Bücking 2021, Rivin-Schlenker 1999, Pinkall-Springborn 2021,
Sawhney-Crane 2017

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
2026-06-14 06:00:29 +00:00

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# References
## Primary source
This library implements the algorithms from:
| | |
|---|---|
| **Sechelmann***Variational Methods for Discrete Surface Parameterization: Applications and Implementation*, Doctoral thesis, TU Berlin 2016 | The complete mathematical foundation: discrete conformal equivalence, variational angle-sum functionals, Newton solver, uniformization, period matrices, holonomy. DOI: [10.14279/depositonce-5415](https://depositonce.tu-berlin.de/items/8e2988b2-d991-45b5-aad5-9fb7988f3b2f) · CC BY-SA 4.0 |
Java reference implementation: [github.com/varylab/conformallab](https://github.com/varylab/conformallab)
---
## References by module
> **Status-Konvention.** Die „Used in"-Spalte nennt das Modul *oder* die Phase.
> Ein Verweis auf eine **ausgelieferte** Phase (Code existiert, getestet) ist mit
> ✅ markiert; ein Verweis auf eine **geplante/Forschungs**-Phase mit 🔜. Nur die
> ✅-Quellen sind Grundlage des aktuellen Codes; 🔜-Quellen belegen Roadmap-Ziele
> (vgl. auch Abschnitt „Phase 10 references (future research)" unten und
> `novelty-statement.md` §6 „What conformallab++ is not").
>
> | Marker | Bedeutung | Phasen |
> |---|---|---|
> | ✅ | implementiert & getestet | 9a.1, 9a.2, 9b-analytic, Cut-Graph, Hessians |
> | 🔜 | geplant / Forschung | 9d.2, 9f, 10a, 10b, 10c |
| Reference | Used in |
|---|---|
| ✅ **Springborn***Ideal Hyperbolic Polyhedra and Discrete Uniformization*, Discrete & Computational Geometry **64** (2020), pp. 63108. DOI: [10.1007/s00454-019-00132-8](https://doi.org/10.1007/s00454-019-00132-8) | `hyper_ideal_geometry.hpp` — ζ₁₃/ζ₁₄/ζ₁₅ functions; `hyper_ideal_functional.hpp` |
| ✅ **Springborn***A variational principle for weighted Delaunay triangulations and hyperideal polyhedra*, J. Differential Geometry **78**(2) (2008), pp. 333367. arXiv: [math/0603097](https://arxiv.org/abs/math/0603097) | Tetrahedron volume with one ideal vertex: `calculateTetrahedronVolumeWithIdealVertexAtGamma` in `hyper_ideal_utility.hpp` (Phase 9b analytic Hessian). ⚠️ *Korrektur:* war fälschlich als „KolpakovMednykh 2006" zitiert — dieses Autorenpaar hat 2006 kein gemeinsames Paper veröffentlicht. Die Java-Quelle verlinkt korrekt auf math/0603097 (= Springborn 2008); der falsche Autorenname wurde beim C++-Port hinzugefügt.* |
| ✅ **Ushijima***A Volume Formula for Generalised Hyperbolic Tetrahedra*, in: Prékopa, Molnár (eds.) *Non-Euclidean Geometries*, Mathematics and Its Applications vol. 581, Springer 2006. DOI: [10.1007/0-387-29555-0_13](https://doi.org/10.1007/0-387-29555-0_13). arXiv: [math/0309216](https://arxiv.org/abs/math/0309216) (2003) | Tetrahedron volume with three ideal vertices: `calculateTetrahedronVolumeFullyIdeal` in `hyper_ideal_utility.hpp`. ⚠️ *Korrektur:* war fälschlich als „Meyerhoff, Ushijima — A Note on the Dirichlet Domain — The Epstein Birthday Schrift" zitiert. Meyerhoff ist kein Autor; Titel und Buch waren beide falsch. Die Java-Quelle verlinkt korrekt auf DOI 10.1007/0-387-29555-0_13 ohne Autorennamen. |
| **Pinkall, Polthier***Computing Discrete Minimal Surfaces and Their Conjugates*, Experimental Mathematics **2**(1), pp. 1536 (1993). DOI: [10.1080/10586458.1993.10504266](https://doi.org/10.1080/10586458.1993.10504266) | `euclidean_hessian.hpp` — cotangent Laplacian |
| **Bobenko, Springborn***Variational Principles for Circle Patterns and Koebe's Theorem*, Trans. Amer. Math. Soc. **356**(2), pp. 659689 (2004). arXiv: [math/0203250](https://arxiv.org/abs/math/0203250) | Variational angle-sum framework underlying all three functionals |
| **Luo***Combinatorial Yamabe Flow on Surfaces*, Commun. Contemp. Math. **6**(5), pp. 765780 (2004). DOI: [10.1142/S0219199704001501](https://doi.org/10.1142/S0219199704001501). arXiv: [math/0306167](https://arxiv.org/abs/math/0306167) | Inversive-distance functional — **new research** in Phase 9a.2 (no Java original; implemented from this paper + Glickenstein 2011 + Bowers-Stephenson 2004) |
| **Bowers, Stephenson***Uniformizing dessins and Belyĭ maps via circle packing*, Memoirs of the AMS 170(805) (2004) | Introduces **inversive-distance circle packings** (used in Phase 9a.2). *Hinweis:* die zur Initialisierung benutzte Formel I_ij = (²r_i²r_j²)/(2 r_i r_j) ist die **klassische** inversive Distanz (vgl. Glickenstein §5.2: ℓ²=r_i²+r_j²+2r_ir_jη), nicht eine eigene „Bowers-Stephenson-Identität" — BS liefern die Packungstheorie, nicht diese Formel. |
| **Glickenstein***Discrete conformal variations and scalar curvature on piecewise flat two- and three-dimensional manifolds*, J. Differential Geometry **87**(2) (2011), pp. 201238 | Analytic Hessian of the inversive-distance functional. ⚠️ *Korrektur:* die Arbeit nummeriert Gleichungen **nicht** im Format „(4.6)" — der Verweis ist durch die **§5.2**-Parametrisierung ²_ij = r²_i + r²_j + 2 r_i r_j η_ij zu ersetzen. Cross-correspondence: η_ij ist die inversive Distanz und entspricht dem Kosinus des **Supplements** des Schnittwinkels (Schnitt bei arccos(η_ij)) — also I_ij = cos θ_e **nur bis aufs Vorzeichen/Supplement**, nicht wörtlich. |
| ✅ **Bobenko, Pinkall, Springborn***Discrete conformal maps and ideal hyperbolic polyhedra*, Geometry & Topology **19**(4) (2015), pp. 21552215. arXiv: [1005.2698](https://arxiv.org/abs/1005.2698) (first posted 2010) | Face-based circle-packing functional (`CPEuclideanFunctional.java``cp_euclidean_functional.hpp`, Phase 9a.1) |
| **Schläfli***On the multiple integral ∫dx dy …*, Quarterly Journal of Pure and Applied Mathematics (1858/60) | Klassische Schläfli-Differentialformel (dV = −½ Σ_e _e dθ_e). ⚠️ *Hinweis:* die in Phase 9b-analytic benutzte **Randterm-Form** `2 dV = Σ_e aₑ dαₑ + Σ_v bᵥ dβᵥ` steht **nicht** bei Schläfli 1858, sondern ist die verallgemeinerte Fassung für Mannigfaltigkeiten mit Rand → korrekter Beleg: **RivinSchlenker 1999** (Phase-10-Liste). Schläfli 1858 nur als historischer Ursprung zitieren. |
| **Erickson, Whittlesey***Greedy Optimal Homotopy and Homology Generators*, SODA (2005) | `cut_graph.hpp` — tree-cotree algorithm |
| **Bobenko, Springborn***A Discrete LaplaceBeltrami Operator for Simplicial Surfaces*, Discrete & Computational Geometry (2007) | Background for cotangent weights |
| **Desbrun, Kanso, Tong***Discrete Differential Forms for Computational Modeling*, SIGGRAPH Course Notes (2006) | Discrete exterior calculus background for Phase 10a |
| **Soliman, Slepčev, Crane***Optimal Cone Singularities for Conformal Flattening*, ACM Transactions on Graphics **37**(4), Article 105 (2018). DOI: [10.1145/3197517.3201367](https://doi.org/10.1145/3197517.3201367) | L¹-optimal automatic cone placement — **Phase 9d.2** (non-Euclidean cone extensions). Provides the optimisation algorithm for choosing cone positions automatically; complements Bobenko-Lutz 2025 on non-Euclidean settings. |
| **Bobenko, Lutz***Decorated Discrete Conformal Equivalence in Non-Euclidean Geometries*, Discrete & Computational Geometry (2025). arXiv: [2310.17529](https://arxiv.org/abs/2310.17529) | **Phase 9d.2**: extends DCE to hyperbolic + spherical geometry with Penner-coordinate decorations; unifies cone singularities and hyperideal cusps in one algebraic framework. |
| **Bobenko, Lutz***Decorated Discrete Conformal Maps and Convex Polyhedral Cusps*, IMRN 2024(12), pp. 95059534. arXiv: [2305.10988](https://arxiv.org/abs/2305.10988) | **Phase 10b/10c**: discrete uniformization theorem for decorated piecewise Euclidean surfaces; connects Phase 2/3 hyperideal vertices (cusps at ∞) to the period matrix and fundamental domain. |
| **Lutz***Canonical Tessellations of Decorated Hyperbolic Surfaces*, Geometriae Dedicata 217 (2023). arXiv: [2206.13461](https://arxiv.org/abs/2206.13461) | **Phase 10c**: canonical Delaunay tessellations in Penner coordinates; unifies the decorated framework with the fundamental domain construction for genus g ≥ 2. |
| **Lutz***Decorated Discrete Conformal Equivalence, Canonical Tessellations, and Polyhedral Realization* (PhD thesis, TU Berlin, 2024). DOI: [10.14279/depositonce-20357](https://doi.org/10.14279/depositonce-20357) | Comprehensive single reference for Phases 9d.2, 10b, 10c — collects Bobenko-Lutz 2024/2025 and Lutz 2023 with complete proofs. |
| **Bowers, Bowers, Lutz***Rigidity of Koebe Polyhedra and Inversive Distance Circle Packings* (2026). arXiv: [2601.22903](https://arxiv.org/abs/2601.22903) | **Phase 9b-analytic + Phase 10c'** (KoebePolyhedron): theoretical uniqueness/rigidity for Koebe polyhedra and inversive-distance circle packings (incl. the tangency case); supports correctness of the analytic Hessian and the KAT construction. |
| **Alexa, Wardetzky***Discrete Laplacians on General Polygonal Meshes*, ACM SIGGRAPH (2011). DOI: [10.1145/1964921.1964997](https://doi.org/10.1145/1964921.1964997) | **Phase 9f**: virtual-node polygon Laplacian extending Pinkall-Polthier to non-triangular meshes. Enables DCE on quad/Voronoi meshes without triangulation. |
| **Bunge, Herholz, Kazhdan, Botsch***Polygon Laplacian Made Simple*, Computer Graphics Forum **39**(2) (2020), pp. 303313. DOI: [10.1111/cgf.13931](https://doi.org/10.1111/cgf.13931) | **Phase 9f**: virtual-vertex polygon Laplacian — fügt pro Polygon einen virtuellen Knoten ein (impliziter Triangle-Fan), erweitert die cotangent-Diskretisierung auf nicht-konvexe/nicht-planare Polygone. (Alternative DEC-Variante: **de Goes, Butts, Desbrun**, *Discrete Differential Operators on Polygonal Meshes*, ACM TOG **39**(4) (2020), DOI [10.1145/3386569.3392389](https://doi.org/10.1145/3386569.3392389).) |
---
## geometry-central cross-reference *(optional comparison track)*
> These references relate to an alternative implementation of the same
> mathematical problem. They are not prerequisites for conformallab++,
> but are relevant for cross-validation and possible algorithmic adoptions
> (→ GC-1/2/3 in the phase roadmap, → Section 9 in `validation.md`).
| Reference | Relevance |
|---|---|
| **Gillespie, Springborn, Crane***Discrete Conformal Equivalence of Polyhedral Surfaces*, ACM SIGGRAPH 2021. DOI: [10.1145/3450626.3459763](https://doi.org/10.1145/3450626.3459763) | Implemented in **geometry-central**. Extends Springborn 2020 with intrinsic triangulations and Ptolemaic flips. Solves the same DCE problem as conformallab++, but with a different algorithm. |
| **Sharp, Soliman, Crane***Navigating Intrinsic Triangulations*, ACM SIGGRAPH 2019 | Algorithmic basis for `SignpostIntrinsicTriangulation` in geometry-central — relevant for GC-2 (optional pre-conditioning). |
**Note on Springborn 2020:**
The paper *"Ideal Hyperbolic Polyhedra and Discrete Uniformization"*
(Springborn, Discrete & Computational Geometry 2020) is **already implemented in
conformallab++** — it is the direct reference for the HyperIdeal geometry mode
(`hyper_ideal_geometry.hpp`). The geometry-central implementation (Gillespie 2021)
builds on this paper and augments it with Ptolemaic flips.
---
## Phase 10 references (future research)
| Reference | Relevant for |
|---|---|
| **Farkas, Kra***Riemann Surfaces*, Springer GTM 71 | Siegel period matrix, Teichmüller theory |
| **Siegel***Topics in Complex Function Theory, Vol. 2*, Wiley | Siegel upper half-space H_g, Sp(2g,) reduction |
| **Bobenko, Mercat, Schmies***Conformal Structures and Period Matrices of Polyhedral Surfaces*, in: Bobenko, Klein (eds.) *Computational Approach to Riemann Surfaces*, Lecture Notes in Mathematics vol. 2013, Springer 2011, pp. 213226. DOI: [10.1007/978-3-642-17413-1_7](https://doi.org/10.1007/978-3-642-17413-1_7) | Discrete period matrices on polyhedral surfaces |
| **Bobenko, Bücking***Convergence of discrete period matrices and discrete holomorphic integrals for ramified coverings of the Riemann sphere*, Math. Phys. Anal. Geom. **24**, Art. 23 (2021). DOI: [10.1007/s11040-021-09394-2](https://doi.org/10.1007/s11040-021-09394-2) | Phase 10b: discrete Siegel period matrix Ωᵢⱼ from cotangent-weighted integration **plus** the convergence result Ω_discrete → Ω_smooth under refinement (für ramified coverings) — belegt die Diskret-zu-glatt-Aussage in `novelty-statement.md §3.3. |
| **Rivin, Schlenker** — *The Schläfli formula in Einstein manifolds with boundary*, Electron. Res. Announc. AMS **5** (1999), pp. 1823 | Phase 9b-analytic: modern form of the Schläfli identity `2 dV = Σ aₑ dα` for manifolds with boundary — the bilinear form used to derive the analytic HyperIdeal Hessian. |
| **Pinkall, Springborn** — *A discrete version of Liouville's theorem on conformal maps*, Geometriae Dedicata **214** (2021), pp. 389398. arXiv: [1911.00966](https://arxiv.org/abs/1911.00966) | Phase 10b uniqueness: proves that the discrete conformal structure (and hence Ω) is a conformal invariant — the discrete Liouville theorem. Justifies that conformallab++ outputs a canonical representative. |
| **Born, Bücking, Springborn** — *Quasiconformal distortion of projective transformations and discrete conformal maps*, Discrete & Computational Geometry **57**(2), pp. 305317 (2017). DOI: [10.1007/s00454-016-9854-7](https://doi.org/10.1007/s00454-016-9854-7). arXiv: [1505.01341](https://arxiv.org/abs/1505.01341) (preprint 2015) | Phase 10c error analysis: quantifies how well the discrete H²/Γ embedding approximates the smooth hyperbolic metric; error bounds for the Fuchsian group representation. |
| **Knöppel, Crane, Pinkall, Schröder** — *Stripe Patterns on Surfaces*, ACM Transactions on Graphics **34**(4), Article 39 (SIGGRAPH 2015). DOI: [10.1145/2767000](https://doi.org/10.1145/2767000). ⚠️ *Kein arXiv-Preprint* (arXiv:1502.06686 ist ein anderes Paper — Data-Driven Shape Analysis — und wurde aus dem papers/-Ordner entfernt). | Phase 10a cross-validation: applies discrete holomorphic 1-forms to direction field design; geometry-central provides an independent C++ implementation to cross-check the Phase 10a `DiscreteHolomorphicFormUtility` port. |
| **Sawhney, Crane***Boundary First Flattening*, ACM TOG **37**(1), Article 5 (2017). DOI: [10.1145/3132705](https://doi.org/10.1145/3132705) | Complementary method to Phase 9d: boundary-prescribed conformal flattening — user specifies boundary shape, interior conforms freely. Contrast: conformallab++ prescribes cone angles in the interior; BFF prescribes the boundary. Alternative approach for applications needing controlled boundary. |