pith. sign in

arxiv: 2509.16764 · v2 · pith:VY2S3MTSnew · submitted 2025-09-20 · 🧮 math.RT · math.CO

Frieze patterns in representation theory

Pith reviewed 2026-05-21 22:08 UTC · model grok-4.3

classification 🧮 math.RT math.CO
keywords frieze patternscluster algebrasrepresentation theoryGrassmanniantriangulationscluster categoriescombinatorics
0
0 comments X

The pith

Frieze patterns connect combinatorially to triangulations of polygons and Grassmannian cluster categories.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

This review examines how frieze patterns, infinite arrays of numbers where every diamond of four neighboring entries obeys the same arithmetic rule, link to geometric and algebraic objects. It covers results showing that these patterns correspond to triangulations of polygons and appear within Grassmannian cluster algebras and cluster categories. The paper then turns to recent explicit connections between friezes and objects inside Grassmannian cluster categories. A sympathetic reader would care because the links turn a purely combinatorial rule into a tool for organizing data from representation theory and cluster algebras.

Core claim

Frieze patterns are infinite arrays obeying the diamond rule, first studied by Coxeter in the late 1960s and by Conway and Coxeter in 1973. The paper reviews striking results that tie these combinatorially defined arrays to triangulations of polygons, to Grassmannian cluster algebras, and to Grassmannian cluster categories, followed by a focus on recent results that link friezes directly to the categories.

What carries the argument

The frieze pattern, an infinite array satisfying the fixed diamond arithmetic rule, which maps onto triangulations and supplies combinatorial labels for objects in Grassmannian cluster categories.

Load-bearing premise

The reviewed literature accurately captures the established connections between frieze patterns and structures in Grassmannian cluster categories.

What would settle it

A concrete counterexample would be a frieze pattern whose entries cannot be realized by any triangulation of a polygon or by any object in a Grassmannian cluster category.

read the original abstract

Friezes patterns are infinite arrays of numbers, in which every four neighbouring vertices arranged in a diamond satisfy the same arithmetic rule. Introduced in the late 1960s by Coxeter, and further studied by Conway and Coxeter in their remarkable papers from $1973$, this topic has been nearly forgotten for over thirty years. But since the discovery of connections to cluster algebras and categories of type $A$, interest in friezes has exploded, several generalizations have been studied, and links to geometry and combinatorics have been explored. In this article we will review some of the most striking results connecting the purely combinatorially defined friezes with triangulations of polygons, Grassmannian cluster algebras and (Grassmannian) cluster categories. Then we will focus on Grassmannian cluster categories and some recent results linking them to friezes.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

1 major / 2 minor

Summary. The manuscript is a review article that recalls the definition and history of frieze patterns (introduced by Coxeter and studied by Conway-Coxeter), notes their long dormancy, and then surveys the striking connections that have been established since the advent of cluster algebras: links to triangulations of polygons, to Grassmannian cluster algebras, and to Grassmannian cluster categories. The second half focuses on recent results that realize friezes inside Grassmannian cluster categories.

Significance. A clear, well-organized survey of these connections would be useful to the representation-theory and cluster-algebra communities, as it assembles results that are currently scattered across several papers and makes the combinatorial-to-categorical dictionary more accessible.

major comments (1)
  1. [Section on Grassmannian cluster categories] The section that surveys recent results on Grassmannian cluster categories should state the precise statements (or at least the main theorems) being summarized rather than only describing them at a high level; without explicit formulations it is difficult for a reader to judge whether the review accurately captures the scope and limitations of the cited works.
minor comments (2)
  1. [Abstract] The abstract opens with the ungrammatical phrase 'Friezes patterns'; this should be corrected to 'Frieze patterns'.
  2. A short table or diagram comparing the different generalizations of friezes (ordinary, generalized, tropical, etc.) would help readers keep the various variants distinct.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for the positive assessment of our survey and the recommendation of minor revision. The single major comment is addressed below.

read point-by-point responses
  1. Referee: The section that surveys recent results on Grassmannian cluster categories should state the precise statements (or at least the main theorems) being summarized rather than only describing them at a high level; without explicit formulations it is difficult for a reader to judge whether the review accurately captures the scope and limitations of the cited works.

    Authors: We agree that including explicit formulations of the main theorems would improve the utility of the survey. In the revised manuscript we will add the precise statements of the key results from the cited works on Grassmannian cluster categories, while preserving the overall accessibility and flow of the section. revision: yes

Circularity Check

0 steps flagged

Review article summarizes external literature with no original derivations or self-referential reductions

full rationale

The paper is explicitly a review article that surveys prior results on frieze patterns, their combinatorial definitions, and established links to polygon triangulations, Grassmannian cluster algebras, and cluster categories. No new theorems, equations, predictions, or fitted parameters are derived within the manuscript itself. All connections are attributed to external literature (e.g., Conway-Coxeter, type-A cluster structures), with no load-bearing steps that reduce by construction to the paper's own inputs, self-citations, or ansatzes. The content is therefore self-contained against external benchmarks.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

This is a review paper that summarizes prior literature on frieze patterns and their connections to cluster algebras and categories. No new free parameters, axioms, or invented entities are introduced by the current work.

pith-pipeline@v0.9.0 · 5660 in / 1054 out tokens · 44696 ms · 2026-05-21T22:08:04.051779+00:00 · methodology

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Lean theorems connected to this paper

Citations machine-checked in the Pith Canon. Every link opens the source theorem in the public Lean library.

What do these tags mean?
matches
The paper's claim is directly supported by a theorem in the formal canon.
supports
The theorem supports part of the paper's argument, but the paper may add assumptions or extra steps.
extends
The paper goes beyond the formal theorem; the theorem is a base layer rather than the whole result.
uses
The paper appears to rely on the theorem as machinery.
contradicts
The paper's claim conflicts with a theorem or certificate in the canon.
unclear
Pith found a possible connection, but the passage is too broad, indirect, or ambiguous to say the theorem truly supports the claim.

Reference graph

Works this paper leans on

98 extracted references · 98 canonical work pages · 2 internal anchors

  1. [1]

    Cluster structures for the a-infinity singularity

    Jenny August, Man Wai Cheung, Eleonore Faber, Sira Gratz, and Sibylle Schroll. Cluster structures for the a-infinity singularity. J. Lond. Math. Soc. (2) , 107(6):2121--2149, 2023

  2. [2]

    Categories for G rassmannian cluster algebras of infinite rank

    Jenny August, Man-Wai Cheung, Eleonore Faber, Sira Gratz, and Sibylle Schroll. Categories for G rassmannian cluster algebras of infinite rank. Int. Math. Res. Not. IMRN , (2):1166--1210, 2024

  3. [3]

    Cluster categories for algebras of global dimension 2 and quivers with potential

    Claire Amiot. Cluster categories for algebras of global dimension 2 and quivers with potential. Ann. Inst. Fourier (Grenoble) , 59(6):2525--2590, 2009

  4. [4]

    Maurice Auslander, Idun Reiten, and Sverre O. Smal . Representation theory of A rtin algebras , volume 36 of Cambridge Studies in Advanced Mathematics . Cambridge University Press, Cambridge, 1997. Corrected reprint of the 1995 original

  5. [5]

    Ibrahim Assem, Christophe Reutenauer, and David Smith. Friezes. Adv. Math. , 225(6):3134--3165, 2010

  6. [6]

    Elements of the representation theory of associative algebras

    Ibrahim Assem, Daniel Simson, and Andrzej Skowro\' n ski. Elements of the representation theory of associative algebras. V ol. 1 , volume 65 of London Mathematical Society Student Texts . Cambridge University Press, Cambridge, 2006. Techniques of representation theory

  7. [7]

    Frieze patterns of integers

    Karin Baur. Frieze patterns of integers. Math. Intelligencer , 43(2):47--54, 2021

  8. [8]

    Grassmannians and cluster structures

    Karin Baur. Grassmannians and cluster structures. Bull. Iranian Math. Soc. , 47(suppl. 1):S5--S33, 2021

  9. [9]

    K. Baur, L. Bittmann, E. Gunawan, , G. Todorov, and E. Y ld r m. Infinite friezes of affine type D , 2024

  10. [10]

    Cluster categories from G rassmannians and root combinatorics

    Karin Baur, Dusko Bogdanic, and Ana Garcia Elsener. Cluster categories from G rassmannians and root combinatorics. Nagoya Math. J. , 240:322--354, 2020

  11. [11]

    Jacobsen, Maitreyee C

    Karin Baur, Ilke Canakci, Karin M. Jacobsen, Maitreyee C. Kulkarni, and Gordana Todorov. Infinite friezes and triangulations of annuli. J. Algebra Appl. , 23(12):Paper No. 2450207, 31, 2024

  12. [12]

    Mutation of friezes

    Karin Baur, Eleonore Faber, Sira Gratz, Khrystyna Serhiyenko, and Gordana Todorov. Mutation of friezes. Bull. Sci. Math. , 142:1--48, 2018

  13. [13]

    Friezes satisfying higher SL _k -determinants

    Karin Baur, Eleonore Faber, Sira Gratz, Khrystyna Serhiyenko, and Gordana Todorov. Friezes satisfying higher SL _k -determinants. Algebra Number Theory , 15(1):29--68, 2021

  14. [14]

    Classification of singularities of cluster algebras of finite type: the case of trivial coefficients

    Angelica Benito, Eleonore Faber, Hussein Mourtada, and Bernd Schober. Classification of singularities of cluster algebras of finite type: the case of trivial coefficients. Glasg. Math. J. , 65(1):170--204, 2023

  15. [15]

    Parsons, and Manuela Tschabold

    Karin Baur, Klemens Fellner, Mark J. Parsons, and Manuela Tschabold. Growth behaviour of periodic tame friezes. Rev. Mat. Iberoam. , 35(2):575--606, 2019

  16. [16]

    Transfinite mutations in the completed infinity-gon

    Karin Baur and Sira Gratz. Transfinite mutations in the completed infinity-gon. J. Combin. Theory Ser. A , 155:321--359, 2018

  17. [17]

    Buchweitz, G.-M

    R.-O. Buchweitz, G.-M. Greuel, and F.-O. Schreyer. Cohen- M acaulay modules on hypersurface singularities. II . Invent. Math. , 88(1):165--182, 1987

  18. [18]

    A. B. Buan, O. Iyama, I. Reiten, and J. Scott. Cluster structures for 2- C alabi- Y au categories and unipotent groups. Compos. Math. , 145(4):1035--1079, 2009

  19. [19]

    King, and Bethany R

    Karin Baur, Alastair D. King, and Bethany R. Marsh. Dimer models and cluster categories of G rassmannians. Proc. Lond. Math. Soc. (3) , 113(2):213--260, 2016

  20. [20]

    Karin Baur and Robert J. Marsh. Frieze patterns for punctured discs. J. Algebraic Combin. , 30(3):349--379, 2009

  21. [21]

    Tilting theory and cluster combinatorics

    Aslak Bakke Buan, Bethany Marsh, Markus Reineke, Idun Reiten, and Gordana Todorov. Tilting theory and cluster combinatorics. Adv. Math. , 204(2):572--618, 2006

  22. [22]

    Cluster-tilted algebras

    Aslak Bakke Buan, Bethany Marsh, and Idun Reiten. Cluster-tilted algebras. Trans. Amer. Math. Soc. , 359(1):323--332, 2007

  23. [23]

    Parsons, and Manuela Tschabold

    Karin Baur, Mark J. Parsons, and Manuela Tschabold. Infinite friezes. European J. Combin. , 54:220--237, 2016

  24. [24]

    SL_k -tilings of the plane

    Francois Bergeron and Christophe Reutenauer. SL_k -tilings of the plane. Illinois J. Math. , 54(1):263--300, 2010

  25. [25]

    Maximal C ohen- M acaulay modules and T ate cohomology , volume 262 of Mathematical Surveys and Monographs

    Ragnar-Olaf Buchweitz. Maximal C ohen- M acaulay modules and T ate cohomology , volume 262 of Mathematical Surveys and Monographs . American Mathematical Society, Providence, RI, [2021] 2021. With appendices and an introduction by Luchezar L. Avramov, Benjamin Briggs, Srikanth B. Iyengar and Janina C. Letz

  26. [26]

    Conway and Harold S

    John H. Conway and Harold S. M. Coxeter. Triangulated polygons and frieze patterns. Math. Gaz. , 57(400):87--94, 1973

  27. [27]

    Conway and Harold S.M

    John H. Conway and Harold S.M. Coxeter. Triangulated polygons and frieze patterns. Math. Gaz. , 57(401):175--183, 1973

  28. [28]

    Cluster algebras as H all algebras of quiver representations

    Philippe Caldero and Fr \'e d \'e ric Chapoton. Cluster algebras as H all algebras of quiver representations. Comment. Math. Helv. , 81(3):595--616, 2006

  29. [29]

    Caldero, F

    P. Caldero, F. Chapoton, and R. Schiffler. Quivers with relations arising from clusters ( A_n case). Trans. Amer. Math. Soc. , 358(3):1347--1364, 2006

  30. [30]

    Infinite rank surface cluster algebras

    Ilke Canakci and Anna Felikson. Infinite rank surface cluster algebras. Adv. Math. , 352:862--942, 2019

  31. [31]

    Super C aldero- C hapoton map for type A

    Ilke Canakc , Francesca Fedele, Ana Garcia Elsener, and Khrystyna Serhiyenko. Super C aldero- C hapoton map for type A . J. Algebra , 678:326--375, 2025

  32. [32]

    Frieze patterns with coefficients

    Michael Cuntz, Thorsten Holm, and Peter J rgensen. Frieze patterns with coefficients. Forum Math. Sigma , 8:Paper No. e17, 36, 2020

  33. [33]

    Non-commutative friezes and their determinants, the non-commutative L aurent phenomenon for weak friezes, and frieze gluing

    Michael Cuntz, Thorsten Holm, and Peter J rgensen. Non-commutative friezes and their determinants, the non-commutative L aurent phenomenon for weak friezes, and frieze gluing. Adv. in Appl. Math. , 171:Paper No. 102940, 33, 2025

  34. [34]

    Cluster categories for completed infinity-gons I : C ategorifying triangulations

    Ilke Canakci, Martin Kalck, and Matthew Pressland. Cluster categories for completed infinity-gons I : C ategorifying triangulations. J. Lond. Math. Soc. (2) , 111(2):Paper No. e70092, 31, 2025

  35. [35]

    H. S. M. Coxeter. Introduction to geometry . John Wiley & Sons, Inc., New York-London-Sydney, second edition, 1969

  36. [36]

    Harold S. M. Coxeter. Frieze patterns. Acta Arith. , 18:297--310, 1971

  37. [37]

    H. S. M. Coxeter. Regular complex polytopes . Cambridge University Press, Cambridge, second edition, 1991

  38. [38]

    H. S. M. Coxeter and J. F. Rigby. Frieze patterns, triangulated polygons and dichromatic symmetry

  39. [39]

    Cordes and D

    Craig M. Cordes and D. P. Roselle. Generalized frieze patterns. Duke Math. J. , 39:637--648, 1972

  40. [40]

    On wild frieze patterns

    Michael Cuntz. On wild frieze patterns. Exp. Math. , 26(3):342--348, 2017

  41. [41]

    de Saint Germain, M

    A. de Saint Germain, M. Huang, and J. Lu. Friezes of cluster algebras of geometric type , 2023

  42. [42]

    Penrose tilings, friezes, and the A_ -singularity , 2025

    \"O zg \"u r Esentepe and Eleonore Faber. Penrose tilings, friezes, and the A_ -singularity , 2025. in preparation

  43. [43]

    Homological algebra on a complete intersection, with an application to group representations

    David Eisenbud. Homological algebra on a complete intersection, with an application to group representations. Trans. Amer. Math. Soc. , 260(1):35--64, 1980

  44. [44]

    Friezes - Some (mostly online) resources

    Ana Felikson. Friezes - Some (mostly online) resources . https://www.maths.dur.ac.uk/users/anna.felikson/Projects/frieze/frieze-res.html

  45. [45]

    Thomas A. Fisher. On the Enlargement by Pr\"ufer Objects of the Cluster Category of type A_ , 2016

  46. [46]

    On cluster algebras with coefficients and 2- C alabi- Y au categories

    Changjian Fu and Bernhard Keller. On cluster algebras with coefficients and 2- C alabi- Y au categories. Trans. Amer. Math. Soc. , 362(2):859--895, 2010

  47. [47]

    [Gab62] P

    Eleonore Faber, Bethany Marsh, and Matthew Pressland. Reduction of Frobenius extriangulated categories , 2023. https://arxiv.org/abs/2308.16232

  48. [48]

    Non-zero integral friezes

    B. Fontaine. Non-zero integral friezes . 2014. https://arxiv.org/abs/1409.6026

  49. [49]

    Counting friezes in type D_n

    Bruce Fontaine and Pierre-Guy Plamondon. Counting friezes in type D_n . J. Algebraic Combin. , 44(2):433--445, 2016

  50. [50]

    Heronian friezes

    Sergey Fomin and Linus Setiabrata. Heronian friezes. Int. Math. Res. Not. IMRN , (1):651--697, 2021

  51. [51]

    Faber and B

    E. Faber and B. Schober. Frieze patterns and combinatorics of curve singularities . 2024. https://arxiv.org/abs/2412.02422

  52. [52]

    Introduction to cluster algebras

    Sergey Fomin, Lauren Williams, and Andrei Zelevinsky. Introduction to cluster algebras. chapters 1-3, 2016

  53. [53]

    Introduction to cluster algebras

    Sergey Fomin, Lauren Williams, and Andrei Zelevinsky. Introduction to cluster algebras. chapters 4-5, 2017

  54. [54]

    Introduction to cluster algebras

    Sergey Fomin, Lauren Williams, and Andrei Zelevinsky. Introduction to cluster algebras. chapters 6, 2020

  55. [55]

    Cluster algebras

    Sergey Fomin and Andrei Zelevinsky. Cluster algebras. I . F oundations. J. Amer. Math. Soc. , 15(2):497--529, 2002

  56. [56]

    Cluster algebras

    Sergey Fomin and Andrei Zelevinsky. Cluster algebras. II . F inite type classification. Invent. Math. , 154(1):63--121, 2003

  57. [57]

    Cluster algebras

    Sergey Fomin and Andrei Zelevinsky. Cluster algebras. IV . C oefficients. Compos. Math. , 143(1):112--164, 2007

  58. [58]

    Grabowski and Sira Gratz

    Jan E. Grabowski and Sira Gratz. Cluster algebras of infinite rank. J. Lond. Math. Soc. (2) , 89(2):337--363, 2014. With an appendix by Michael Groechenig

  59. [59]

    Ind-cluster algebras and infinite Grassmannians , 2025

    Sira Gratz and Christian Korff. Ind-cluster algebras and infinite Grassmannians , 2025. https://arxiv.org/abs/2505.01228

  60. [60]

    Partial flag varieties and preprojective algebras

    Christof Geiss, Bernard Leclerc, and Jan Schr\" o er. Partial flag varieties and preprojective algebras. Ann. Inst. Fourier (Grenoble) , 58(3):825--876, 2008

  61. [61]

    Gunawan and G

    E. Gunawan and G. Muller. Superunitary regions of cluster algebras . 2022. https://arxiv.org/abs/2208.14521

  62. [62]

    L. Guo. On tropical friezes associated with D ynkin diagrams. Int. Math. Res. Not. IMRN , (18):4243--4284, 2013

  63. [63]

    On the derived category of a finite-dimensional algebra

    Dieter Happel. On the derived category of a finite-dimensional algebra. Comment. Math. Helv. , 62(3):339--389, 1987

  64. [64]

    Triangulated categories in the representation theory of finite-dimensional algebras , volume 119 of London Mathematical Society Lecture Note Series

    Dieter Happel. Triangulated categories in the representation theory of finite-dimensional algebras , volume 119 of London Mathematical Society Lecture Note Series . Cambridge University Press, Cambridge, 1988

  65. [65]

    Coxeter friezes and triangulations of polygons

    Claire-Soizic Henry. Coxeter friezes and triangulations of polygons. Amer. Math. Monthly , 120(6):553--558, 2013

  66. [66]

    On a cluster category of infinite D ynkin type, and the relation to triangulations of the infinity-gon

    Thorsten Holm and Peter J rgensen. On a cluster category of infinite D ynkin type, and the relation to triangulations of the infinity-gon. Math. Z. , 270(1-2):277--295, 2012

  67. [67]

    Cluster categories coming from cyclic posets

    Kiyoshi Igusa and Gordana Todorov. Cluster categories coming from cyclic posets. Comm. Algebra , 43(10):4367--4402, 2015

  68. [68]

    Mutation in triangulated categories and rigid C ohen- M acaulay modules

    Osamu Iyama and Yuji Yoshino. Mutation in triangulated categories and rigid C ohen- M acaulay modules. Invent. Math. , 172(1):117--168, 2008

  69. [69]

    King, and Xiuping Su

    Bernt Tore Jensen, Alastair D. King, and Xiuping Su. A categorification of G rassmannian cluster algebras. Proc. Lond. Math. Soc. (3) , 113(2):185--212, 2016

  70. [70]

    Cluster algebras, quiver representations and triangulated categories

    Bernhard Keller. Cluster algebras, quiver representations and triangulated categories. In Triangulated categories , volume 375 of London Math. Soc. Lecture Note Ser. , pages 76--160. Cambridge Univ. Press, Cambridge, 2010

  71. [71]

    B. Keller. Cluster algebras and cluster categories. Bull. Iranian Math. Soc. , 37(2):187--234, 2011

  72. [72]

    Bethany R. Marsh. Lecture notes on cluster algebras . Zurich Lectures in Advanced Mathematics. European Mathematical Society (EMS), Z\"urich, 2013

  73. [73]

    Arithmetics of 2-friezes

    Sophie Morier-Genoud. Arithmetics of 2-friezes. J. Algebraic Combin. , 36(4):515--539, 2012

  74. [74]

    Coxeter's frieze patterns at the crossroads of algebra, geometry and combinatorics

    Sophie Morier-Genoud. Coxeter's frieze patterns at the crossroads of algebra, geometry and combinatorics. Bull. Lond. Math. Soc. , 47(6):895--938, 2015

  75. [75]

    Symplectic frieze patterns

    Sophie Morier-Genoud. Symplectic frieze patterns. SIGMA Symmetry Integrability Geom. Methods Appl. , 15:Paper No. 089, 36, 2019

  76. [76]

    Farey boat: continued fractions and triangulations, modular group and polygon dissections

    Sophie Morier-Genoud and Valentin Ovsienko. Farey boat: continued fractions and triangulations, modular group and polygon dissections. Jahresber. Dtsch. Math.-Ver. , 121(2):91--136, 2019

  77. [77]

    Linear difference equations, frieze patterns, and the combinatorial G ale transform

    Sophie Morier-Genoud, Valentin Ovsienko, Richard Evan Schwartz, and Serge Tabachnikov. Linear difference equations, frieze patterns, and the combinatorial G ale transform. Forum Math. Sigma , 2:e22, 45, 2014

  78. [78]

    2-frieze patterns and the cluster structure of the space of polygons

    Sophie Morier-Genoud, Valentin Ovsienko, and Serge Tabachnikov. 2-frieze patterns and the cluster structure of the space of polygons. Ann. Inst. Fourier (Grenoble) , 62(3):937--987, 2012

  79. [79]

    Progress on Infinite Cluster Categories Related to Triangulations of the (Punctured) Disk , 2022

    Fatemeh Mohammadi, Job Daisie Rock, and Francesca Zaffalon. Progress on Infinite Cluster Categories Related to Triangulations of the (Punctured) Disk , 2022. https://arxiv.org/abs/2209.15513

  80. [80]

    A treatise on the theory of determinants

    Thomas Muir. A treatise on the theory of determinants . Revised and enlarged by William H. Metzler. Dover Publications, Inc., New York, 1960

Showing first 80 references.