Or: SO3 webs in action
I will explain how to use a representation theoretical gadget called webs to prove the four color theorem.
There is still a computer component involved.
The slides and their source code can be found on the website www.dtubbenhauer.com
The document provides instructions for using a graphing calculator to find the roots, vertex, maximum or minimum value of quadratic functions. It lists steps like determining the nature of the roots, finding the roots, y-intercept, axis of symmetry, and turning point. Examples of quadratic functions are given, along with homework problems that ask students to provide details about the roots, intercepts, vertex and concavity for each function.
1. A round trip ticket between Japan and New York costs approximately $1602.
2. Courtside seats for an NBA game between the Atlanta Hawks and Golden State Warriors cost $17,402.25 each.
3. A 2015 Toyota Camry costs $24,800.
The document contains several math word problems and questions about sequences, series, fractals, and exponential growth. It does not provide solutions to the problems.
The document discusses different methods for visually representing data distributions, including frequency tables, stem-and-leaf plots, dotplots, and back-to-back stem-and-leaf plots. It provides examples of collecting and representing data on the number of pets students have, the ages of Wimbledon tennis champions from 1970-1990, and the number of siblings of students in a class. Key terms discussed include distribution, stem-and-leaf plot, maximum, minimum, range, cluster, gap, outlier, frequency, and dotplot.
This contains some hints and discussions about how to implement Grids in a Object Oriented language. Specifically the discussion is made with Java in mind, but obviosly, not limited to it.
UNION AND INTERSECTION USING VENN DIAGRAM.pptxRizaCatli2
The probabilities of drawing a card that is either a diamond or a face card from a standard 52-card deck is 13/52. The probability of drawing a 7 or a red card is 26/52. The probability of drawing a jack or an ace is 16/52.
The document discusses using a graphing calculator to find the roots and vertex of quadratic functions. It provides examples of quadratic functions and steps to determine the nature of the roots, find the actual roots, y-intercept, axis of symmetry, turning point, and whether the graph is concave up or down in order to sketch the graph. The goal is to demonstrate how to use a graphing calculator to analyze quadratic functions.
These are the slides from a talk that I gave at Durham University in 2013. Tatami coverings (also known as tatami tilings) are a restricted exact covering by monomino 1x1 tiles and domino 2x2 tiles of grid-regions.
The restriction is that no four tiles can meet.
I discovered and studied the resulting structure during my PhD.
The document provides instructions for using a graphing calculator to find the roots, vertex, maximum or minimum value of quadratic functions. It lists steps like determining the nature of the roots, finding the roots, y-intercept, axis of symmetry, and turning point. Examples of quadratic functions are given, along with homework problems that ask students to provide details about the roots, intercepts, vertex and concavity for each function.
1. A round trip ticket between Japan and New York costs approximately $1602.
2. Courtside seats for an NBA game between the Atlanta Hawks and Golden State Warriors cost $17,402.25 each.
3. A 2015 Toyota Camry costs $24,800.
The document contains several math word problems and questions about sequences, series, fractals, and exponential growth. It does not provide solutions to the problems.
The document discusses different methods for visually representing data distributions, including frequency tables, stem-and-leaf plots, dotplots, and back-to-back stem-and-leaf plots. It provides examples of collecting and representing data on the number of pets students have, the ages of Wimbledon tennis champions from 1970-1990, and the number of siblings of students in a class. Key terms discussed include distribution, stem-and-leaf plot, maximum, minimum, range, cluster, gap, outlier, frequency, and dotplot.
This contains some hints and discussions about how to implement Grids in a Object Oriented language. Specifically the discussion is made with Java in mind, but obviosly, not limited to it.
UNION AND INTERSECTION USING VENN DIAGRAM.pptxRizaCatli2
The probabilities of drawing a card that is either a diamond or a face card from a standard 52-card deck is 13/52. The probability of drawing a 7 or a red card is 26/52. The probability of drawing a jack or an ace is 16/52.
The document discusses using a graphing calculator to find the roots and vertex of quadratic functions. It provides examples of quadratic functions and steps to determine the nature of the roots, find the actual roots, y-intercept, axis of symmetry, turning point, and whether the graph is concave up or down in order to sketch the graph. The goal is to demonstrate how to use a graphing calculator to analyze quadratic functions.
These are the slides from a talk that I gave at Durham University in 2013. Tatami coverings (also known as tatami tilings) are a restricted exact covering by monomino 1x1 tiles and domino 2x2 tiles of grid-regions.
The restriction is that no four tiles can meet.
I discovered and studied the resulting structure during my PhD.
Or: Beyond linear.
Abstract: Equivariant neural networks are neural networks that incorporate symmetries. The nonlinear activation functions in these networks result in interesting nonlinear equivariant maps between simple representations, and motivate the key player of this talk: piecewise linear representation theory.
Disclaimer: No one is perfect, so please mind that there might be mistakes and typos.
dtubbenhauer@gmail.com
Corrected slides: dtubbenhauer.com/talks.html
The mathematics of AI (machine learning mathematically)Daniel Tubbenhauer
Or: Forward, loss, backward
Abstract: This presentation is an introduction to the mathematics that govern neural networks in machine learning.
Disclaimer: No one is perfect, so please mind that there might be mistakes and typos.
dtubbenhauer@gmail.com
Corrected slides: dtubbenhauer.com/talks.html
Abstract: Computer algebra is about developing tools for the exact solution of equations. Here equation can mean differential equations, linear or polynomial equations or inequalities, recurrences, equations in groups, algebras or categories, tensor equations etc. It is widely used to experiment in mathematics, science and engineering. In fact, it is used everywhere in mathematics, even while working on "very abstract" questions.
This talk is a short and friendly introduction to some of the main ideas of exact yet fast algorithms in computation with the focus on multiplications of numbers and polynomials.
Or: Quantum algebra = geometry + algebra
You may not have heard of knot theory, the mathematical study of knots. Inspired by real-world knots such as those in shoelaces and ropes, knot theory is a fairly new field of mathematics which nowadays sits in the intersection of algebra and geometry, with applications beyond mathematics itself. This talk is a friendly overview of how knots and algebra fit together nicely.
Disclaimer: No one is perfect, so please mind that there might be mistakes and typos.
dtubbenhauer@gmail.com
Slides (if I need to update the slides): tubbenhauer.com/talks.html
This document provides an overview of representation theory of monoidal categories, also known as cell theory for monoidal categories. It begins with an introduction motivating the generalization of representation theory from groups to monoids and monoidal categories. It then discusses examples of finitary and fiat monoidal categories, including representation categories of finite groups and diagram categories. The document concludes with an introduction to cells in monoidal categories, which are equivalence classes that measure information loss.
Or: Cell theory for algebras
In this series of talks we explain how representation theory of monoids, algebras and monoidal categories can all be based on the theory of cells.
This is part 2 of 3.
Disclaimer: No one is perfect, so please mind that there might be mistakes and typos.
dtubbenhauer@gmail.com
Slides (if I need to update the slides): tubbenhauer.com/talks.html
Or: Cell theory for monoid
In this series of talks we explain how representation theory of monoids, algebras and monoidal categories can all be based on the theory of cells.
This is part 1 of 3.
Disclaimer: No one is perfect, so please mind that there might be mistakes and typos.
dtubbenhauer@gmail.com
Slides (if I need to update the slides): tubbenhauer.com/talks.html
Representation theory of monoids and monoidal categoriesDaniel Tubbenhauer
This document provides an overview of representation theory of monoids and monoidal categories. It begins by introducing monoids and monoidal categories, and how representation theory of monoids generalizes and categorifies representation theory of groups. It then discusses the theory of monoids developed by Green and others in the 1940s, including cell structures that measure information loss. Finally, it covers the classification of simple representations of monoids due to Clifford, Munn, and Ponizovskiı̆, relating them to representations of maximal subgroups via H-reduction.
Or: Invariant theory, magnetism, subfactors and skein
This talk is a very biased collection of my attempt to understand the history of category theory, from Eilenberg and MacLane to monoidal categories and alike.
Disclaimer: No one is perfect, so please mind that there might be mistakes and typos.
dtubbenhauer@gmail.com
Slides: dtubbenhauer.com/talks.html
Or: Representing symmetries
This talk is a summary and a motivation why one should study representation theory and its categorification.
Disclaimer: No one is perfect, so please mind that there might be mistakes and typos.
dtubbenhauer@gmail.com
Slides: dtubbenhauer.com/talks.html
Or: ADE and all that
This talk is a summary of the history of subfactors, starting with the analytic definitions, to Jones' subfactors to skein theory.
Disclaimer: No one is perfect, so please mind that there might be mistakes and typos.
dtubbenhauer@gmail.com
Slides: dtubbenhauer.com/talks.html
Or: Invariant theory, magnetism, subfactors and skein
This talk is a summary of the history of the Temperley-Lieb calculus, starting with famous works of Rumer-Teller-Weyl and Temperley-Lieb, over subfactors to skein theory.
Disclaimer: No one is perfect, so please mind that there might be mistakes and typos.
dtubbenhauer@gmail.com
Slides: dtubbenhauer.com/talks.html
Or: From ice to R-matrices
This talk is a summary of the history of quantum groups, describe how they arose from questions in statistical mechanics. The keyword is the Yang-Baxter equation, which was crucial for the development of the field.
Disclaimer: No one is perfect, so please mind that there might be mistakes and typos.
dtubbenhauer@gmail.com
Corrected slides: dtubbenhauer.com/talks.html
(June 12, 2024) Webinar: Development of PET theranostics targeting the molecu...Scintica Instrumentation
Targeting Hsp90 and its pathogen Orthologs with Tethered Inhibitors as a Diagnostic and Therapeutic Strategy for cancer and infectious diseases with Dr. Timothy Haystead.
PPT on Direct Seeded Rice presented at the three-day 'Training and Validation Workshop on Modules of Climate Smart Agriculture (CSA) Technologies in South Asia' workshop on April 22, 2024.
Travis Hills of MN is Making Clean Water Accessible to All Through High Flux ...Travis Hills MN
By harnessing the power of High Flux Vacuum Membrane Distillation, Travis Hills from MN envisions a future where clean and safe drinking water is accessible to all, regardless of geographical location or economic status.
Or: Beyond linear.
Abstract: Equivariant neural networks are neural networks that incorporate symmetries. The nonlinear activation functions in these networks result in interesting nonlinear equivariant maps between simple representations, and motivate the key player of this talk: piecewise linear representation theory.
Disclaimer: No one is perfect, so please mind that there might be mistakes and typos.
dtubbenhauer@gmail.com
Corrected slides: dtubbenhauer.com/talks.html
The mathematics of AI (machine learning mathematically)Daniel Tubbenhauer
Or: Forward, loss, backward
Abstract: This presentation is an introduction to the mathematics that govern neural networks in machine learning.
Disclaimer: No one is perfect, so please mind that there might be mistakes and typos.
dtubbenhauer@gmail.com
Corrected slides: dtubbenhauer.com/talks.html
Abstract: Computer algebra is about developing tools for the exact solution of equations. Here equation can mean differential equations, linear or polynomial equations or inequalities, recurrences, equations in groups, algebras or categories, tensor equations etc. It is widely used to experiment in mathematics, science and engineering. In fact, it is used everywhere in mathematics, even while working on "very abstract" questions.
This talk is a short and friendly introduction to some of the main ideas of exact yet fast algorithms in computation with the focus on multiplications of numbers and polynomials.
Or: Quantum algebra = geometry + algebra
You may not have heard of knot theory, the mathematical study of knots. Inspired by real-world knots such as those in shoelaces and ropes, knot theory is a fairly new field of mathematics which nowadays sits in the intersection of algebra and geometry, with applications beyond mathematics itself. This talk is a friendly overview of how knots and algebra fit together nicely.
Disclaimer: No one is perfect, so please mind that there might be mistakes and typos.
dtubbenhauer@gmail.com
Slides (if I need to update the slides): tubbenhauer.com/talks.html
This document provides an overview of representation theory of monoidal categories, also known as cell theory for monoidal categories. It begins with an introduction motivating the generalization of representation theory from groups to monoids and monoidal categories. It then discusses examples of finitary and fiat monoidal categories, including representation categories of finite groups and diagram categories. The document concludes with an introduction to cells in monoidal categories, which are equivalence classes that measure information loss.
Or: Cell theory for algebras
In this series of talks we explain how representation theory of monoids, algebras and monoidal categories can all be based on the theory of cells.
This is part 2 of 3.
Disclaimer: No one is perfect, so please mind that there might be mistakes and typos.
dtubbenhauer@gmail.com
Slides (if I need to update the slides): tubbenhauer.com/talks.html
Or: Cell theory for monoid
In this series of talks we explain how representation theory of monoids, algebras and monoidal categories can all be based on the theory of cells.
This is part 1 of 3.
Disclaimer: No one is perfect, so please mind that there might be mistakes and typos.
dtubbenhauer@gmail.com
Slides (if I need to update the slides): tubbenhauer.com/talks.html
Representation theory of monoids and monoidal categoriesDaniel Tubbenhauer
This document provides an overview of representation theory of monoids and monoidal categories. It begins by introducing monoids and monoidal categories, and how representation theory of monoids generalizes and categorifies representation theory of groups. It then discusses the theory of monoids developed by Green and others in the 1940s, including cell structures that measure information loss. Finally, it covers the classification of simple representations of monoids due to Clifford, Munn, and Ponizovskiı̆, relating them to representations of maximal subgroups via H-reduction.
Or: Invariant theory, magnetism, subfactors and skein
This talk is a very biased collection of my attempt to understand the history of category theory, from Eilenberg and MacLane to monoidal categories and alike.
Disclaimer: No one is perfect, so please mind that there might be mistakes and typos.
dtubbenhauer@gmail.com
Slides: dtubbenhauer.com/talks.html
Or: Representing symmetries
This talk is a summary and a motivation why one should study representation theory and its categorification.
Disclaimer: No one is perfect, so please mind that there might be mistakes and typos.
dtubbenhauer@gmail.com
Slides: dtubbenhauer.com/talks.html
Or: ADE and all that
This talk is a summary of the history of subfactors, starting with the analytic definitions, to Jones' subfactors to skein theory.
Disclaimer: No one is perfect, so please mind that there might be mistakes and typos.
dtubbenhauer@gmail.com
Slides: dtubbenhauer.com/talks.html
Or: Invariant theory, magnetism, subfactors and skein
This talk is a summary of the history of the Temperley-Lieb calculus, starting with famous works of Rumer-Teller-Weyl and Temperley-Lieb, over subfactors to skein theory.
Disclaimer: No one is perfect, so please mind that there might be mistakes and typos.
dtubbenhauer@gmail.com
Slides: dtubbenhauer.com/talks.html
Or: From ice to R-matrices
This talk is a summary of the history of quantum groups, describe how they arose from questions in statistical mechanics. The keyword is the Yang-Baxter equation, which was crucial for the development of the field.
Disclaimer: No one is perfect, so please mind that there might be mistakes and typos.
dtubbenhauer@gmail.com
Corrected slides: dtubbenhauer.com/talks.html
(June 12, 2024) Webinar: Development of PET theranostics targeting the molecu...Scintica Instrumentation
Targeting Hsp90 and its pathogen Orthologs with Tethered Inhibitors as a Diagnostic and Therapeutic Strategy for cancer and infectious diseases with Dr. Timothy Haystead.
PPT on Direct Seeded Rice presented at the three-day 'Training and Validation Workshop on Modules of Climate Smart Agriculture (CSA) Technologies in South Asia' workshop on April 22, 2024.
Travis Hills of MN is Making Clean Water Accessible to All Through High Flux ...Travis Hills MN
By harnessing the power of High Flux Vacuum Membrane Distillation, Travis Hills from MN envisions a future where clean and safe drinking water is accessible to all, regardless of geographical location or economic status.
The technology uses reclaimed CO₂ as the dyeing medium in a closed loop process. When pressurized, CO₂ becomes supercritical (SC-CO₂). In this state CO₂ has a very high solvent power, allowing the dye to dissolve easily.
The cost of acquiring information by natural selectionCarl Bergstrom
This is a short talk that I gave at the Banff International Research Station workshop on Modeling and Theory in Population Biology. The idea is to try to understand how the burden of natural selection relates to the amount of information that selection puts into the genome.
It's based on the first part of this research paper:
The cost of information acquisition by natural selection
Ryan Seamus McGee, Olivia Kosterlitz, Artem Kaznatcheev, Benjamin Kerr, Carl T. Bergstrom
bioRxiv 2022.07.02.498577; doi: https://doi.org/10.1101/2022.07.02.498577
When I was asked to give a companion lecture in support of ‘The Philosophy of Science’ (https://shorturl.at/4pUXz) I decided not to walk through the detail of the many methodologies in order of use. Instead, I chose to employ a long standing, and ongoing, scientific development as an exemplar. And so, I chose the ever evolving story of Thermodynamics as a scientific investigation at its best.
Conducted over a period of >200 years, Thermodynamics R&D, and application, benefitted from the highest levels of professionalism, collaboration, and technical thoroughness. New layers of application, methodology, and practice were made possible by the progressive advance of technology. In turn, this has seen measurement and modelling accuracy continually improved at a micro and macro level.
Perhaps most importantly, Thermodynamics rapidly became a primary tool in the advance of applied science/engineering/technology, spanning micro-tech, to aerospace and cosmology. I can think of no better a story to illustrate the breadth of scientific methodologies and applications at their best.
Describing and Interpreting an Immersive Learning Case with the Immersion Cub...Leonel Morgado
Current descriptions of immersive learning cases are often difficult or impossible to compare. This is due to a myriad of different options on what details to include, which aspects are relevant, and on the descriptive approaches employed. Also, these aspects often combine very specific details with more general guidelines or indicate intents and rationales without clarifying their implementation. In this paper we provide a method to describe immersive learning cases that is structured to enable comparisons, yet flexible enough to allow researchers and practitioners to decide which aspects to include. This method leverages a taxonomy that classifies educational aspects at three levels (uses, practices, and strategies) and then utilizes two frameworks, the Immersive Learning Brain and the Immersion Cube, to enable a structured description and interpretation of immersive learning cases. The method is then demonstrated on a published immersive learning case on training for wind turbine maintenance using virtual reality. Applying the method results in a structured artifact, the Immersive Learning Case Sheet, that tags the case with its proximal uses, practices, and strategies, and refines the free text case description to ensure that matching details are included. This contribution is thus a case description method in support of future comparative research of immersive learning cases. We then discuss how the resulting description and interpretation can be leveraged to change immersion learning cases, by enriching them (considering low-effort changes or additions) or innovating (exploring more challenging avenues of transformation). The method holds significant promise to support better-grounded research in immersive learning.
ESA/ACT Science Coffee: Diego Blas - Gravitational wave detection with orbita...Advanced-Concepts-Team
Presentation in the Science Coffee of the Advanced Concepts Team of the European Space Agency on the 07.06.2024.
Speaker: Diego Blas (IFAE/ICREA)
Title: Gravitational wave detection with orbital motion of Moon and artificial
Abstract:
In this talk I will describe some recent ideas to find gravitational waves from supermassive black holes or of primordial origin by studying their secular effect on the orbital motion of the Moon or satellites that are laser ranged.
The debris of the ‘last major merger’ is dynamically youngSérgio Sacani
The Milky Way’s (MW) inner stellar halo contains an [Fe/H]-rich component with highly eccentric orbits, often referred to as the
‘last major merger.’ Hypotheses for the origin of this component include Gaia-Sausage/Enceladus (GSE), where the progenitor
collided with the MW proto-disc 8–11 Gyr ago, and the Virgo Radial Merger (VRM), where the progenitor collided with the
MW disc within the last 3 Gyr. These two scenarios make different predictions about observable structure in local phase space,
because the morphology of debris depends on how long it has had to phase mix. The recently identified phase-space folds in Gaia
DR3 have positive caustic velocities, making them fundamentally different than the phase-mixed chevrons found in simulations
at late times. Roughly 20 per cent of the stars in the prograde local stellar halo are associated with the observed caustics. Based
on a simple phase-mixing model, the observed number of caustics are consistent with a merger that occurred 1–2 Gyr ago.
We also compare the observed phase-space distribution to FIRE-2 Latte simulations of GSE-like mergers, using a quantitative
measurement of phase mixing (2D causticality). The observed local phase-space distribution best matches the simulated data
1–2 Gyr after collision, and certainly not later than 3 Gyr. This is further evidence that the progenitor of the ‘last major merger’
did not collide with the MW proto-disc at early times, as is thought for the GSE, but instead collided with the MW disc within
the last few Gyr, consistent with the body of work surrounding the VRM.
ESR spectroscopy in liquid food and beverages.pptxPRIYANKA PATEL
With increasing population, people need to rely on packaged food stuffs. Packaging of food materials requires the preservation of food. There are various methods for the treatment of food to preserve them and irradiation treatment of food is one of them. It is the most common and the most harmless method for the food preservation as it does not alter the necessary micronutrients of food materials. Although irradiated food doesn’t cause any harm to the human health but still the quality assessment of food is required to provide consumers with necessary information about the food. ESR spectroscopy is the most sophisticated way to investigate the quality of the food and the free radicals induced during the processing of the food. ESR spin trapping technique is useful for the detection of highly unstable radicals in the food. The antioxidant capability of liquid food and beverages in mainly performed by spin trapping technique.
Gadgets for management of stored product pests_Dr.UPR.pdf
Three colors suffice
1. Three colors suffice
Or: SO3 webs in action
AcceptChange what you cannot changeaccept
I report on work of Tait, Temperley–Lieb, Yamada & Turaev, and many more
Three colors suffice Or: SO3 webs in action January 2024 1 / 5
2. Tait’s webs
▶ Task Color countries such that two countries that share a border get different colors
▶ Above A four coloring of the world (counting the ocean as a country)
▶ Question How many colors are needed when varying over all maps?
Three colors suffice Or: SO3 webs in action January 2024 2 / 5
3. Tait’s webs
▶ Task Color countries such that two countries that share a border get different colors
▶ Above A four coloring of the world (counting the ocean as a country)
▶ Question How many colors are needed when varying over all maps?
It is easy to see that one needs at least four colors:
Three colors suffice Or: SO3 webs in action January 2024 2 / 5
4. Tait’s webs
▶ Guthrie ∼1852 was coloring counties of England
▶ They conjectured that only four colors are needed and wrote De Morgan
▶ De Morgan popularized the question
Three colors suffice Or: SO3 webs in action January 2024 2 / 5
5. Tait’s webs
▶ Guthrie ∼1852 was coloring counties of England
▶ They conjectured that only four colors are needed and wrote De Morgan
▶ De Morgan popularized the question
The 4CT (“four colors suffice”) was the first major theorem with a computer assisted proof
Appel–Haken’s proof ∼1976 has
770ish pages
with 500 pages of
“cases to check”
The book is from ∼1989
:
Today A different proof due to Tait & Temperley–Lieb & Yamada & Turaev
Spoiler The proof also has a computer component
Three colors suffice Or: SO3 webs in action January 2024 2 / 5
6. Tait’s webs
▶ Guthrie ∼1852 was coloring counties of England
▶ They conjectured that only four colors are needed and wrote De Morgan
▶ De Morgan popularized the question
How to go to graphs? You know the drill:
Here is an example why this is actually cool:
Northamptonshire borders Lincolnshire with a ≈20m border
That is impossible to see on the real map!
Three colors suffice Or: SO3 webs in action January 2024 2 / 5
7. Tait’s webs
▶ Math formulation Every planar graph is four vertex-colorable
▶ Tait ∼1880 We can restrict to triangulated planar graphs
▶ Why? We can keep the coloring after removing edges!
Three colors suffice Or: SO3 webs in action January 2024 2 / 5
8. Tait’s webs
▶ Tait ∼1880 We have
4CT (vertices) ⇔ triangulated 4CT (vertices) ⇔ trivalent 4CT (faces)
▶ Why? The dual of a triangulated planar graph is a trivalent planar graph
Three colors suffice Or: SO3 webs in action January 2024 2 / 5
9. Tait’s webs
▶ Tait ∼1880 We have
4CT (vertices) ⇔ triangulated 4CT (vertices) ⇔ trivalent 4CT (faces)
▶ Why? The dual of a triangulated planar graph is a trivalent planar graph
Tait’s webs = trivalent planar graphs (the name came later)
Examples
Three colors suffice Or: SO3 webs in action January 2024 2 / 5
10. Tait’s webs
3 edge coloring :
▶ 3CT is the statement that every trivalent planar bridgeless graph admits a 3
edge coloring
▶ Tait ∼1880 We have
4CT (vertices) ⇔ 3CT (edges)
Three colors suffice Or: SO3 webs in action January 2024 2 / 5
11. Tait’s webs
3 edge coloring :
▶ 3CT is the statement that every trivalent planar bridgeless graph admits a 3
edge coloring
▶ Tait ∼1880 We have
4CT (vertices) ⇔ 3CT (edges)
Examples
Three colors suffice Or: SO3 webs in action January 2024 2 / 5
12. Tait’s webs
3 edge coloring :
▶ 3CT is the statement that every trivalent planar bridgeless graph admits a 3
edge coloring
▶ Tait ∼1880 We have
4CT (vertices) ⇔ 3CT (edges)
Examples
Bridge = edge that disconnects
the graph after removal
“Bridges ↭ countries touching themselves”
so we disregard them
Three colors suffice Or: SO3 webs in action January 2024 2 / 5
13. Tait’s webs
3 edge coloring :
▶ 3CT is the statement that every trivalent planar bridgeless graph admits a 3
edge coloring
▶ Tait ∼1880 We have
4CT (vertices) ⇔ 3CT (edges)
Proof sketch: 4CT ⇒ 3CT
Identify the 4 colors with elements of Z/2Z × Z/2Z
and use the rule (a) + (b) = (a + b):
Three colors suffice Or: SO3 webs in action January 2024 2 / 5
14. Tait’s webs
3 edge coloring :
▶ 3CT is the statement that every trivalent planar bridgeless graph admits a 3
edge coloring
▶ Tait ∼1880 We have
4CT (vertices) ⇔ 3CT (edges)
Proof sketch: 4CT ⇐ 3CT
Identify the 4 colors with elements of Z/2Z × Z/2Z
get “two-color subgraphs” color and overlay them
and use the rule (a) + (b) = (a + b):
Three colors suffice Or: SO3 webs in action January 2024 2 / 5
15. Temperley–Lieb’s webs
gen:
rels:
▶ Define a category Web(SO3) with: Objects = •⊗n
; Morphisms =
everything you can get from a trivalent vertex
▶ Make it Z-linear and quotient by the relations above + isotopies
Three colors suffice Or: SO3 webs in action January 2024 π / 5
16. Temperley–Lieb’s webs
gen:
rels:
▶ Define a category Web(SO3) with: Objects = •⊗n
; Morphisms =
everything you can get from a trivalent vertex
▶ Make it Z-linear and quotient by the relations above + isotopies
We define this as a monoidal category with
◦ = vertical stacking, ⊗ = horizontal juxtaposition
Isotopy relations are of the form
and the interesting relations are the combinatorial ones
Three colors suffice Or: SO3 webs in action January 2024 π / 5
17. Temperley–Lieb’s webs
▶ The above relations hold
▶ Upshot Every web evaluates to a number in Web(SO3) Web evaluation
▶ Essentially done by Temperley–Lieb ∼1971 The web evaluation counts the
number of 3-colorings
Three colors suffice Or: SO3 webs in action January 2024 π / 5
18. Temperley–Lieb’s webs
▶ The above relations hold
▶ Upshot Every web evaluates to a number in Web(SO3) Web evaluation
▶ Essentially done by Temperley–Lieb ∼1971 The web evaluation counts the
number of 3-colorings
Why are 0-5 gon relations enough? Well:
Lemma Every web contains a ≤ 5 gon
Proof Use the Euler characteristic
This is a closed web!
Three colors suffice Or: SO3 webs in action January 2024 π / 5
19. Temperley–Lieb’s webs
▶ The above relations hold
▶ Upshot Every web evaluates to a number in Web(SO3) Web evaluation
▶ Essentially done by Temperley–Lieb ∼1971 The web evaluation counts the
number of 3-colorings
Why does the evaluation count colorings? Well:
Lemma The relations preserve the number of colors
Proof Color the boundary and check, e.g.:
Three colors suffice Or: SO3 webs in action January 2024 π / 5
20. Temperley–Lieb’s webs
▶ The above relations hold
▶ Upshot Every web evaluates to a number in Web(SO3) Web evaluation
▶ Essentially done by Temperley–Lieb ∼1971 The web evaluation counts the
number of 3-colorings
Example
= + = 3 + 32
= 12
We have indeed twelve 3-colorings:
, ,
, ,
, ,
, ,
Three colors suffice Or: SO3 webs in action January 2024 π / 5
21. Temperley–Lieb’s webs
▶ Essentially done by Temperley–Lieb ∼1971 4CT ⇔ every webs evaluates
to a nonzero scalar
▶ The 4CT is then almost immediately true but there is a sign in the pentagon
relation, and there might be cancellations
Three colors suffice Or: SO3 webs in action January 2024 π / 5
22. Temperley–Lieb’s webs
▶ Essentially done by Temperley–Lieb ∼1971 4CT ⇔ every webs evaluates
to a nonzero scalar
▶ The 4CT is then almost immediately true but there is a sign in the pentagon
relation, and there might be cancellations
Two questions remain:
Question 1 Can we beef this up into a proof of 4CT?
Question 2 Where do these relations come from?
Three colors suffice Or: SO3 webs in action January 2024 π / 5
23. Yamada & Turaev’s webs
▶ SO3 = rotations of C3
▶ The real version is topologically SO3 ∼
= S2
/antipodal points
▶ SO3 acts on X = C3
by matrices
Three colors suffice Or: SO3 webs in action January 2024 4 / 5
24. Yamada & Turaev’s webs
• 7→ X
7→ inclusion of 1 into X ⊗ X
7→ inclusion of X into X ⊗ X
▶ Essentially done by Yamada & Turaev ∼1989 We have
Web(SO3) ∼
= Rep(SO3) using the above
▶ Equivalence of categories = they encode the same information
▶ Rep(SO3) = fd reps of SO3 over C
Three colors suffice Or: SO3 webs in action January 2024 4 / 5
25. Yamada & Turaev’s webs
• 7→ X
7→ inclusion of 1 into X ⊗ X
7→ inclusion of X into X ⊗ X
▶ Essentially done by Yamada & Turaev ∼1989 We have
Web(SO3) ∼
= Rep(SO3) using the above
▶ Equivalence of categories = they encode the same information
▶ Rep(SO3) = fd reps of SO3 over C
Upshot Under Web(SO3) ∼
= Rep(SO3) the relations, e.g.
are equations between SO3-equivariant matrices
Example The “I=H” relation is an equation of four 9-by-9 matrices
Three colors suffice Or: SO3 webs in action January 2024 4 / 5
26. Yamada & Turaev’s webs
▶ Recall that we want to show positivity but the pentagon has a sign
▶ Observation Closing the pentagon “minimally” evaluates to a positive number
Three colors suffice Or: SO3 webs in action January 2024 4 / 5
27. Yamada & Turaev’s webs
An unavoidable configuration:
▶ An Euler characteristic argument shows that there are finitely many
“unavoidable configurations” one needs to check similarly
▶ There are finitely many “minimally closures” for each one of them
Three colors suffice Or: SO3 webs in action January 2024 4 / 5
28. Yamada & Turaev’s webs
An unavoidable configuration:
▶ An Euler characteristic argument shows that there are finitely many
“unavoidable configurations” one needs to check similarly
▶ There are finitely many “minimally closures” for each one of them
Theorem
(A) 4CT holds ⇔ (B) finitely many configurations evaluate to a positive number
One can computer verify that (B) holds (too many to do by hand)
Three colors suffice Or: SO3 webs in action January 2024 4 / 5
29. Yamada & Turaev’s webs
An unavoidable configuration:
▶ An Euler characteristic argument shows that there are finitely many
“unavoidable configurations” one needs to check similarly
▶ There are finitely many “minimally closures” for each one of them
Khovanov–Kuperberg ∼1999 essentially showed
that 3-colorings correspond to a base-change matrix
between a standard basis and a dual canonical basis in Rep(SO3)
Example
{v1, v2, v3} basis of X
Identify: = v1, = v2, = v3
↭ v1 ⊗ v1 + v2 ⊗ v2 + v3 ⊗ v3 ∈ X ⊗ X
↭ scalar in front of v1 ⊗ v1
↭ scalar in front of v2 ⊗ v2
↭ scalar in front of v3 ⊗ v3
Theorem
(A) 4CT holds ⇔ (C) finitely many inequalities of matrix entries
One can computer verify that (C) holds (too many to do by hand)
Three colors suffice Or: SO3 webs in action January 2024 4 / 5
30. Tait’s webs
▶ Task Color countries such that two countries that share a border get different colors
▶ Above A four coloring of the world (counting the ocean as a country)
▶ Question How many colors are needed when varying over all maps?
Three colors suffice Or: SO3 webs in action January 2024 2 / 5
Tait’s webs
▶ Guthrie ∼1852 was coloring counties of England
▶ They conjectured that only four colors are needed and wrote De Morgan
▶ De Morgan popularized the question
Three colors suffice Or: SO3 webs in action January 2024 2 / 5
Tait’s webs
▶ Tait ∼1880 We have
4CT (vertices) ⇔ triangulated 4CT (vertices) ⇔ trivalent 4CT (faces)
▶ Why? The dual of a triangulated planar graph is a trivalent planar graph
Three colors suffice Or: SO3 webs in action January 2024 2 / 5
Tait’s webs
3 edge coloring :
▶ 3CT is the statement that every trivalent planar bridgeless graph admits a 3
edge coloring
▶ Tait ∼1880 We have
4CT (vertices) ⇔ 3CT (edges)
Three colors suffice Or: SO3 webs in action January 2024 2 / 5
Tait’s webs
3 edge coloring :
▶ 3CT is the statement that every trivalent planar bridgeless graph admits a 3
edge coloring
▶ Tait ∼1880 We have
4CT (vertices) ⇔ 3CT (edges)
Proof sketch: 4CT ⇒ 3CT
Identify the 4 colors with elements of Z/2Z × Z/2Z
and use the rule (a) + (b) = (a + b):
Three colors suffice Or: SO3 webs in action January 2024 2 / 5
Temperley–Lieb’s webs
▶ The above relations hold
▶ Upshot Every web evaluates to a number in Web(SO3) Web evaluation
▶ Essentially done by Temperley–Lieb ∼1971 The web evaluation counts the
number of 3-colorings
Three colors suffice Or: SO3 webs in action January 2024 π / 5
Temperley–Lieb’s webs
▶ The above relations hold
▶ Upshot Every web evaluates to a number in Web(SO3) Web evaluation
▶ Essentially done by Temperley–Lieb ∼1971 The web evaluation counts the
number of 3-colorings
Why are 0-5 gon relations enough? Well:
Lemma Every web contains a ≤ 5 gon
Proof Use the Euler characteristic
This is a closed web!
Three colors suffice Or: SO3 webs in action January 2024 π / 5
Temperley–Lieb’s webs
▶ The above relations hold
▶ Upshot Every web evaluates to a number in Web(SO3) Web evaluation
▶ Essentially done by Temperley–Lieb ∼1971 The web evaluation counts the
number of 3-colorings
Why does the evaluation count colorings? Well:
Lemma The relations preserve the number of colors
Proof Color the boundary and check, e.g.:
Three colors suffice Or: SO3 webs in action January 2024 π / 5
Yamada & Turaev’s webs
▶ Recall that we want to show positivity but the pentagon has a sign
▶ Observation Closing the pentagon “minimally” evaluates to a positive number
Three colors suffice Or: SO3 webs in action January 2024 4 / 5
There is still much to do...
Three colors suffice Or: SO3 webs in action January 2024 5 / 5
31. Tait’s webs
▶ Task Color countries such that two countries that share a border get different colors
▶ Above A four coloring of the world (counting the ocean as a country)
▶ Question How many colors are needed when varying over all maps?
Three colors suffice Or: SO3 webs in action January 2024 2 / 5
Tait’s webs
▶ Guthrie ∼1852 was coloring counties of England
▶ They conjectured that only four colors are needed and wrote De Morgan
▶ De Morgan popularized the question
Three colors suffice Or: SO3 webs in action January 2024 2 / 5
Tait’s webs
▶ Tait ∼1880 We have
4CT (vertices) ⇔ triangulated 4CT (vertices) ⇔ trivalent 4CT (faces)
▶ Why? The dual of a triangulated planar graph is a trivalent planar graph
Three colors suffice Or: SO3 webs in action January 2024 2 / 5
Tait’s webs
3 edge coloring :
▶ 3CT is the statement that every trivalent planar bridgeless graph admits a 3
edge coloring
▶ Tait ∼1880 We have
4CT (vertices) ⇔ 3CT (edges)
Three colors suffice Or: SO3 webs in action January 2024 2 / 5
Tait’s webs
3 edge coloring :
▶ 3CT is the statement that every trivalent planar bridgeless graph admits a 3
edge coloring
▶ Tait ∼1880 We have
4CT (vertices) ⇔ 3CT (edges)
Proof sketch: 4CT ⇒ 3CT
Identify the 4 colors with elements of Z/2Z × Z/2Z
and use the rule (a) + (b) = (a + b):
Three colors suffice Or: SO3 webs in action January 2024 2 / 5
Temperley–Lieb’s webs
▶ The above relations hold
▶ Upshot Every web evaluates to a number in Web(SO3) Web evaluation
▶ Essentially done by Temperley–Lieb ∼1971 The web evaluation counts the
number of 3-colorings
Three colors suffice Or: SO3 webs in action January 2024 π / 5
Temperley–Lieb’s webs
▶ The above relations hold
▶ Upshot Every web evaluates to a number in Web(SO3) Web evaluation
▶ Essentially done by Temperley–Lieb ∼1971 The web evaluation counts the
number of 3-colorings
Why are 0-5 gon relations enough? Well:
Lemma Every web contains a ≤ 5 gon
Proof Use the Euler characteristic
This is a closed web!
Three colors suffice Or: SO3 webs in action January 2024 π / 5
Temperley–Lieb’s webs
▶ The above relations hold
▶ Upshot Every web evaluates to a number in Web(SO3) Web evaluation
▶ Essentially done by Temperley–Lieb ∼1971 The web evaluation counts the
number of 3-colorings
Why does the evaluation count colorings? Well:
Lemma The relations preserve the number of colors
Proof Color the boundary and check, e.g.:
Three colors suffice Or: SO3 webs in action January 2024 π / 5
Yamada & Turaev’s webs
▶ Recall that we want to show positivity but the pentagon has a sign
▶ Observation Closing the pentagon “minimally” evaluates to a positive number
Three colors suffice Or: SO3 webs in action January 2024 4 / 5
Thanks for your attention!
Three colors suffice Or: SO3 webs in action January 2024 5 / 5