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- 
Commuting Ordinary Differential Operators and the Dixmier Test
 
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Emma Previato, Sonia L. Rueda and Maria-Angeles Zurro
 SIGMA 15 (2019), 101, 23 pages [ abs  
pdf ] 
 
- 
Picard-Vessiot Extensions of Real Differential Fields
 
- 
Teresa Crespo and Zbigniew Hajto
 SIGMA 15 (2019), 100, 11 pages [ abs  
pdf ] 
 
- 
Higher Rank Relations for the Askey-Wilson and $q$-Bannai-Ito Algebra
 
- 
Hadewijch De Clercq
 SIGMA 15 (2019), 099, 32 pages [ abs  
pdf ] 
 
- 
Exact Bohr-Sommerfeld Conditions for the Quantum Periodic Benjamin-Ono Equation
 
- 
Alexander Moll
 SIGMA 15 (2019), 098, 27 pages [ abs  
pdf ] 
 
- 
Fun Problems in Geometry and Beyond
 
- 
Boris Khesin and Serge Tabachnikov
 SIGMA 15 (2019), 097, 21 pages [ abs  
pdf ] 
 
- 
The Real Jacobi Group Revisited
 
- 
Stefan Berceanu
 SIGMA 15 (2019), 096, 50 pages [ abs  
pdf ] 
 
- 
Cohomology of Restricted Filiform Lie Algebras ${\mathfrak m}_2^\lambda(p)$
 
- 
Tyler J. Evans and Alice Fialowski
 SIGMA 15 (2019), 095, 11 pages [ abs  
pdf ] 
 
- 
Bi-Hamiltonian Systems in (2+1) and Higher Dimensions Defined by Novikov Algebras
 
- 
Błażej M. Szablikowski
 SIGMA 15 (2019), 094, 18 pages [ abs  
pdf ] 
 
- 
Three-Dimensional Mirror Self-Symmetry of the Cotangent Bundle of the Full Flag Variety
 
- 
Richárd Rimányi, Andrey Smirnov, Alexander Varchenko and Zijun Zhou
 SIGMA 15 (2019), 093, 22 pages [ abs  
pdf ] 
 
- 
Correlation Functions of the Pfaffian Schur Process Using Macdonald Difference Operators
 
- 
Promit Ghosal
 SIGMA 15 (2019), 092, 37 pages [ abs  
pdf ] 
 
- 
Locally Nilpotent Derivations of Free Algebra of Rank Two
 
- 
Vesselin Drensky and Leonid Makar-Limanov
 SIGMA 15 (2019), 091, 10 pages [ abs  
pdf ] 
 
- 
Quasi-Polynomials and the Singular $[Q,R]=0$ Theorem
 
- 
Yiannis Loizides
 SIGMA 15 (2019), 090, 15 pages [ abs  
pdf ] 
 
- 
Symplectic Frieze Patterns
 
- 
Sophie Morier-Genoud
 SIGMA 15 (2019), 089, 36 pages [ abs  
pdf ] 
 
- 
Variations for Some Painlevé Equations
 
- 
Primitivo B. Acosta-Humánez, Marius van der Put and Jaap Top
 SIGMA 15 (2019), 088, 10 pages [ abs  
pdf ] 
 
- 
On the Geometry of Extended Self-Similar Solutions of the Airy Shallow Water Equations
 
- 
Roberto Camassa, Gregorio Falqui, Giovanni Ortenzi and Marco Pedroni
 SIGMA 15 (2019), 087, 17 pages [ abs  
pdf ] 
 
- 
The Ramificant Determinant
 
- 
Kingshook Biswas and Ricardo Pérez-Marco
 SIGMA 15 (2019), 086, 28 pages [ abs  
pdf ] 
 
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Hitchin Fibrations on Two-Dimensional Moduli Spaces of Irregular Higgs Bundles with One Singular Fiber
 
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Péter Ivanics, András I. Stipsicz and Szilárd Szabó
 SIGMA 15 (2019), 085, 28 pages [ abs  
pdf ] 
 
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Knapp-Stein Type Intertwining Operators for Symmetric Pairs II. - The Translation Principle and Intertwining Operators for Spinors
 
- 
Jan Frahm and Bent Ørsted
 SIGMA 15 (2019), 084, 50 pages [ abs  
pdf ] 
 
- 
Collective Heavy Top Dynamics
 
- 
Tomoki Ohsawa
 SIGMA 15 (2019), 083, 17 pages [ abs  
pdf ] 
 
- 
One Parameter Family of Jordanian Twists
 
- 
Daniel Meljanac, Stjepan Meljanac, Zoran Škoda and Rina Štrajn
 SIGMA 15 (2019), 082, 16 pages [ abs  
pdf ] 
 
- 
A Note on the Derivatives of Isotropic Positive Definite Functions on the Hilbert Sphere
 
- 
Janin Jäger
 SIGMA 15 (2019), 081,   7 pages [ abs  
pdf ] 
 
- 
Half-Spin Tautological Relations and Faber's Proportionalities of Kappa Classes
 
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Elba Garcia-Failde, Reinier Kramer, Danilo Lewański and Sergey Shadrin
 SIGMA 15 (2019), 080, 27 pages [ abs  
pdf ] 
 
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Dispersionless Multi-Dimensional Integrable Systems and Related Conformal Structure Generating Equations of Mathematical Physics
 
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Oksana Ye. Hentosh, Yarema A. Prykarpatsky, Denis Blackmore and Anatolij K. Prykarpatski
 SIGMA 15 (2019), 079, 20 pages [ abs  
pdf ] 
 
- 
The Transition Function of $G_2$ over $S^6$
 
- 
Ádám Gyenge
 SIGMA 15 (2019), 078, 16 pages [ abs  
pdf ] 
 
- 
Modular Group Representations in Combinatorial Quantization with Non-Semisimple Hopf Algebras
 
- 
Matthieu Faitg
 SIGMA 15 (2019), 077, 39 pages [ abs  
pdf ] 
 
- 
Momentum Sections in Hamiltonian Mechanics and Sigma Models
 
- 
Noriaki Ikeda
 SIGMA 15 (2019), 076, 16 pages [ abs  
pdf ] 
 
- 
Twisted de Rham Complex on Line and Singular Vectors in $\widehat{{\mathfrak{sl}_2}}$ Verma Modules
 
- 
Alexey Slinkin and Alexander Varchenko
 SIGMA 15 (2019), 075, 26 pages [ abs  
pdf ] 
 
- 
Combinatorial Expressions for the Tau Functions of $q$-Painlevé V and III Equations
 
- 
Yuya Matsuhira and Hajime Nagoya
 SIGMA 15 (2019), 074, 17 pages [ abs  
pdf ] 
 
- 
A Kähler Compatible Moyal Deformation  of the First Heavenly Equation
 
- 
Marco Maceda and Daniel Martínez-Carbajal
 SIGMA 15 (2019), 073, 16 pages [ abs  
pdf ] 
 
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Spinorially Twisted Spin Structures. II: Twisted Pure Spinors, Special Riemannian Holonomy and Clifford Monopoles
 
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Rafael Herrera and Noemi Santana
 SIGMA 15 (2019), 072, 48 pages [ abs  
pdf ] 
 
- 
Stratified Bundles on Curves and Differential Galois Groups in Positive Characteristic
 
- 
Marius van der Put
 SIGMA 15 (2019), 071, 24 pages [ abs  
pdf ] 
 
- 
Holomorphic Distributions and Connectivity by Integral Curves of Distributions
 
- 
Vladimir A. Zorich
 SIGMA 15 (2019), 070,   6 pages [ abs  
pdf ] 
 
- 
Separability and Symmetry Operators for Painlevé Metrics and their Conformal Deformations
 
- 
Thierry Daudé, Niky Kamran and Francois Nicoleau
 SIGMA 15 (2019), 069, 42 pages [ abs  
pdf ] 
 
- 
Vertex Models and Spin Chains  in Formulas and Pictures
 
- 
Khazret S. Nirov and Alexander V. Razumov
 SIGMA 15 (2019), 068, 67 pages [ abs  
pdf ] 
 
- 
Ergodic Decomposition for Inverse Wishart Measures on Infinite Positive-Definite Matrices
 
- 
Theodoros Assiotis
 SIGMA 15 (2019), 067, 24 pages [ abs  
pdf ] 
 
- 
Scalar Products in Twisted XXX Spin Chain. Determinant Representation
 
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Samuel Belliard and Nikita A. Slavnov
 SIGMA 15 (2019), 066, 30 pages [ abs  
pdf ] 
 
- 
Multiparameter Schur $Q$-Functions Are Solutions of the BKP Hierarchy
 
- 
Natasha Rozhkovskaya
 SIGMA 15 (2019), 065, 14 pages [ abs  
pdf ] 
 
- 
Lagrangian Grassmannians and Spinor Varieties in Characteristic Two
 
- 
Bert van Geemen and Alessio Marrani
 SIGMA 15 (2019), 064, 22 pages [ abs  
pdf ] 
 
- 
Dynamic Equivalence of Control Systems and Infinite Permutation Matrices
 
- 
Jeanne N. Clelland, Yuhao Hu and Matthew W. Stackpole
 SIGMA 15 (2019), 063, 16 pages [ abs  
pdf ] 
 
- 
Integrable Modifications of the Ito-Narita-Bogoyavlensky Equation
 
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Rustem N. Garifullin and Ravil I. Yamilov
 SIGMA 15 (2019), 062, 15 pages [ abs  
pdf ] 
 
- 
Loop Equations for Gromov-Witten Invariant of $\mathbb{P}^1$
 
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Gaëtan Borot and Paul Norbury
 SIGMA 15 (2019), 061, 29 pages [ abs  
pdf ] 
 
- 
Wavepackets on de Sitter Spacetime
 
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João C.A. Barata and Marcos Brum
 SIGMA 15 (2019), 060, 22 pages [ abs  
pdf ] 
 
- 
Third Homology of some Sporadic Finite Groups
 
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Theo Johnson-Freyd and David Treumann
 SIGMA 15 (2019), 059, 38 pages [ abs  
pdf ] 
 
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Linear Differential Systems with Small Coefficients: Various Types of Solvability and their Verification
 
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Moulay A. Barkatou and Renat R. Gontsov
 SIGMA 15 (2019), 058, 15 pages [ abs  
pdf ] 
 
- 
Ricci Flow and Volume Renormalizability
 
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Eric Bahuaud, Rafe Mazzeo and Eric Woolgar
 SIGMA 15 (2019), 057, 21 pages [ abs  
pdf ] 
 
- 
Invariant Nijenhuis Tensors and Integrable Geodesic Flows
 
- 
Konrad Lompert and Andriy Panasyuk
 SIGMA 15 (2019), 056, 30 pages [ abs  
pdf ] 
 
- 
Differential Galois Theory and Isomonodromic Deformations
 
- 
David Blázquez Sanz, Guy Casale and Juan Sebastián Díaz Arboleda
 SIGMA 15 (2019), 055, 35 pages [ abs  
pdf ] 
 
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Interpolations between Jordanian Twists Induced by Coboundary Twists
 
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Andrzej Borowiec, Daniel Meljanac, Stjepan Meljanac and Anna Pachoł
 SIGMA 15 (2019), 054, 22 pages [ abs  
pdf ] 
 
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Orthogonal Dualities of Markov Processes and Unitary Symmetries
 
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Gioia Carinci, Chiara Franceschini, Cristian Giardinà, Wolter Groenevelt and Frank Redig
 SIGMA 15 (2019), 053, 27 pages [ abs  
pdf ] 
 
- 
BPS Spectra, Barcodes and Walls
 
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Michele Cirafici
 SIGMA 15 (2019), 052, 41 pages [ abs  
pdf ] 
 
- 
De Rham 2-Cohomology of Real Flag Manifolds
 
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Viviana del Barco and Luiz Antonio Barrera San Martin
 SIGMA 15 (2019), 051, 23 pages [ abs  
pdf ] 
 
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On Direct Integral Expansion for Periodic Block-Operator Jacobi Matrices and Applications
 
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Leonid Golinskii and Anton Kutsenko
 SIGMA 15 (2019), 050, 14 pages [ abs  
pdf ] 
 
- 
Heteroclinic Orbits and Nonintegrability in Two-Degree-of-Freedom Hamiltonian Systems with Saddle-Centers
 
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Kazuyuki Yagasaki and Shogo Yamanaka
 SIGMA 15 (2019), 049, 17 pages [ abs  
pdf ] 
 
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Invariants in Separated Variables: Yang-Baxter, Entwining and Transfer Maps
 
- 
Pavlos Kassotakis
 SIGMA 15 (2019), 048, 36 pages [ abs  
pdf ] 
 
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Rational KdV Potentials  and Differential Galois Theory
 
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Sonia Jiménez, Juan J. Morales-Ruiz, Raquel Sánchez-Cauce and María-Ángeles Zurro
 SIGMA 15 (2019), 047, 40 pages [ abs  
pdf ] 
 
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Meromorphic Solution of the Degenerate Third Painlevé Equation Vanishing at the Origin
 
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Alexander V. Kitaev
 SIGMA 15 (2019), 046, 53 pages [ abs  
pdf ] 
 
- 
Lax Representations for Separable Systems from Benenti Class
 
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Maciej Błaszak and Ziemowit Domański
 SIGMA 15 (2019), 045, 18 pages [ abs  
pdf ] 
 
- 
A Variational Perspective on Continuum Limits of ABS and Lattice GD Equations
 
- 
Mats Vermeeren
 SIGMA 15 (2019), 044, 35 pages [ abs  
pdf ] 
 
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A Note on Spectral Triples on the Quantum Disk
 
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Slawomir Klimek, Matt McBride and John Wilson Peoples
 SIGMA 15 (2019), 043,   8 pages [ abs  
pdf ] 
 
- 
Classification of Rank 2 Cluster Varieties
 
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Travis Mandel
 SIGMA 15 (2019), 042, 32 pages [ abs  
pdf ] 
 
- 
Hecke Operators on Vector-Valued Modular Forms
 
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Vincent Bouchard, Thomas Creutzig and Aniket Joshi
 SIGMA 15 (2019), 041, 31 pages [ abs  
pdf ] 
 
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Duality between Final-Seed and Initial-Seed  Mutations in Cluster Algebras
 
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Shogo Fujiwara and Yasuaki Gyoda
 SIGMA 15 (2019), 040, 24 pages [ abs  
pdf ] 
 
- 
Higgs Bundles and Geometric Structures on Manifolds
 
- 
Daniele Alessandrini
 SIGMA 15 (2019), 039, 32 pages [ abs  
pdf ] 
 
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The Laurent Extension of Quantum Plane: a Complete List of $U_q(\mathfrak{sl}_2)$-Symmetries
 
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Sergey Sinel'shchikov
 SIGMA 15 (2019), 038, 33 pages [ abs  
pdf ] 
 
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Generalised Darboux-Koenigs Metrics and 3-Dimensional Superintegrable Systems
 
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Allan P. Fordy and Qing Huang
 SIGMA 15 (2019), 037, 30 pages [ abs  
pdf ] 
 
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Construction of Intertwining Operators between Holomorphic Discrete Series Representations
 
- 
Ryosuke Nakahama
 SIGMA 15 (2019), 036, 101 pages [ abs  
pdf ] 
 
- 
An Introduction to Higgs Bundles via Harmonic Maps
 
- 
Qiongling Li
 SIGMA 15 (2019), 035, 30 pages [ abs  
pdf ] 
 
- 
Jacobian Conjecture via Differential Galois Theory
 
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Elżbieta Adamus, Teresa Crespo and Zbigniew Hajto
 SIGMA 15 (2019), 034,   7 pages [ abs  
pdf ] 
 
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$p$-Adic Properties of Hauptmoduln with Applications to Moonshine
 
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Ryan C. Chen, Samuel Marks and Matthew Tyler
 SIGMA 15 (2019), 033, 35 pages [ abs  
pdf ] 
 
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Construction of Two Parametric Deformation of KdV-Hierarchy and Solution in Terms of Meromorphic Functions on the Sigma Divisor of a Hyperelliptic Curve of Genus 3
 
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Takanori Ayano and Victor M. Buchstaber
 SIGMA 15 (2019), 032, 15 pages [ abs  
pdf ] 
 
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A Family of ${\rm GL}_r$ Multiplicative Higgs Bundles on Rational Base
 
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Rouven Frassek and Vasily Pestun
 SIGMA 15 (2019), 031, 42 pages [ abs  
pdf ] 
 
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A Self-Dual Integral Form of the Moonshine Module
 
- 
Scott Carnahan
 SIGMA 15 (2019), 030, 36 pages   [ abs  
pdf ] 
 
- 
The Horn Problem for Real Symmetric and Quaternionic Self-Dual Matrices
 
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Robert Coquereaux and Jean-Bernard Zuber
 SIGMA 15 (2019), 029, 34 pages   [ abs  
pdf ] 
 
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Explicit Solutions for a Nonlinear Vector Model on the Triangular Lattice
 
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V.E. Vekslerchik
 SIGMA 15 (2019), 028, 17 pages   [ abs  
pdf ] 
 
- 
A Short Guide to Orbifold Deconstruction
 
- 
Peter Bantay
 SIGMA 15 (2019), 027, 10 pages   [ abs  
pdf ] 
 
- 
Contravariant Form on Tensor Product of Highest Weight Modules
 
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Andrey I. Mudrov
 SIGMA 15 (2019), 026, 10 pages   [ abs  
pdf ] 
 
- 
A Solvable Deformation of Quantum Mechanics
 
- 
Alba Grassi and Marcos Mariño
 SIGMA 15 (2019), 025, 42 pages   [ abs  
pdf ] 
 
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On Higgs Bundles on Nodal Curves
 
- 
Marina Logares
 SIGMA 15 (2019), 024, 16 pages   [ abs  
pdf ] 
 
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$\tau$-Functions, Birkhoff Factorizations and Difference Equations
 
- 
Darlayne Addabbo and Maarten Bergvelt
 SIGMA 15 (2019), 023, 42 pages   [ abs  
pdf ] 
 
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On a Yang-Mills Type Functional
 
- 
Cătălin Gherghe
 SIGMA 15 (2019), 022,  8 pages   [ abs  
pdf ] 
 
- 
Almost Lie Algebroids and Characteristic Classes
 
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Marcela Popescu and Paul Popescu
 SIGMA 15 (2019), 021, 12 pages   [ abs  
pdf ] 
 
- 
Braid Group Action on Affine Yangian
 
- 
Ryosuke Kodera
 SIGMA 15 (2019), 020, 28 pages   [ abs  
pdf ] 
 
- 
Linear Representations and Frobenius Morphisms of Groupoids
 
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Juan Jesús Barbarán Sánchez and Laiachi El Kaoutit
 SIGMA 15 (2019), 019, 33 pages   [ abs  
pdf ] 
 
- 
Perspectives on the Asymptotic Geometry of the Hitchin Moduli Space
 
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Laura Fredrickson
 SIGMA 15 (2019), 018, 20 pages   [ abs  
pdf ] 
 
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Ghostpeakons and Characteristic Curves for the Camassa-Holm, Degasperis-Procesi and Novikov Equations
 
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Hans Lundmark and Budor Shuaib
 SIGMA 15 (2019), 017, 51 pages   [ abs  
pdf ] 
 
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The $q$-Borel Sum of Divergent Basic Hypergeometric Series ${}_r\varphi_s(a;b;q,x)$
 
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Shunya Adachi
 SIGMA 15 (2019), 016, 12 pages   [ abs  
pdf ] 
 
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A Geometric Approach to the Concept of Extensivity in Thermodynamics
 
- 
Miguel Ángel García-Ariza
 SIGMA 15 (2019), 015, 14 pages   [ abs  
pdf ] 
 
- 
Generalised Umbral Moonshine
 
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Miranda C.N. Cheng, Paul de Lange and Daniel P.Z. Whalen
 SIGMA 15 (2019), 014, 27 pages   [ abs  
pdf ] 
 
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Block-Separation of Variables: a Form of Partial Separation for Natural Hamiltonians
 
- 
Claudia Maria Chanu and Giovanni Rastelli
 SIGMA 15 (2019), 013, 22 pages   [ abs  
pdf ] 
 
- 
The Kashaev Equation and Related Recurrences
 
- 
Alexander Leaf
 SIGMA 15 (2019), 012, 64 pages   [ abs  
pdf ] 
 
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Decomposition of some Witten-Reshetikhin-Turaev Representations into Irreducible Factors
 
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Julien Korinman
 SIGMA 15 (2019), 011, 25 pages   [ abs  
pdf ] 
 
- 
Studying Deformations of Fuchsian Representations with Higgs Bundles
 
- 
Brian Collier
 SIGMA 15 (2019), 010, 32 pages   [ abs  
pdf ] 
 
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On Reducible Degeneration of Hyperelliptic Curves and Soliton Solutions
 
- 
Atsushi Nakayashiki
 SIGMA 15 (2019), 009, 18 pages   [ abs  
pdf ] 
 
- 
Homogeneous Real (2,3,5) Distributions with Isotropy
 
- 
Travis Willse
 SIGMA 15 (2019), 008, 28 pages   [ abs  
pdf ] 
 
- 
Supersingular Elliptic Curves and Moonshine
 
- 
Victor Manuel Aricheta
 SIGMA 15 (2019), 007, 17 pages   [ abs  
pdf ] 
 
- 
Open Problems for Painlevé Equations
 
- 
Peter A. Clarkson
 SIGMA 15 (2019), 006, 20 pages   [ abs  
pdf ] 
 
- 
Solution of an Open Problem about Two Families of Orthogonal Polynomials
 
- 
Walter Van Assche
 SIGMA 15 (2019), 005,   6 pages   [ abs  
pdf ] 
 
- 
Relations between Schoenberg Coefficients on Real and Complex Spheres of Different Dimensions
 
- 
Pier Giovanni Bissiri, Valdir A. Menegatto and Emilio Porcu
 SIGMA 15 (2019), 004, 12 pages   [ abs  
pdf ] 
 
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Note on Character Varieties and Cluster Algebras
 
- 
Kazuhiro Hikami
 SIGMA 15 (2019), 003, 32 pages   [ abs  
pdf ] 
 
- 
Coadjoint Orbits of Lie Algebras and Cartan Class
 
- 
Michel Goze and Elisabeth Remm
 SIGMA 15 (2019), 002, 20 pages   [ abs  
pdf ] 
 
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Aspects of Calabi-Yau Integrable and Hitchin Systems
 
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Florian Beck
 SIGMA 15 (2019), 001, 25 pages   [ abs  
pdf ] 
 
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