Planar graphs | Circle packing | Theorems about circles | Theorems in graph theory
The circle packing theorem (also known as the Koebe–Andreev–Thurston theorem) describes the possible tangency relations between circles in the plane whose interiors are disjoint. A circle packing is a connected collection of circles (in general, on any Riemann surface) whose interiors are disjoint. The intersection graph of a circle packing is the graph having a vertex for each circle, and an edge for every pair of circles that are tangent. If the circle packing is on the plane, or, equivalently, on the sphere, then its intersection graph is called a coin graph; more generally, intersection graphs of interior-disjoint geometric objects are called tangency graphs or contact graphs. Coin graphs are always connected, simple, and planar. The circle packing theorem states that these are the only requirements for a graph to be a coin graph: Circle packing theorem: For every connected simple planar graph G there is a circle packing in the plane whose intersection graph is (isomorphic to) G. (Wikipedia).
Combinatorics and Geometry to Arithmetic of Circle Packings - Nakamura
Speaker: Kei Nakamura (Rutgers) Title: Combinatorics and Geometry to Arithmetic of Circle Packings Abstract: The Koebe-Andreev-Thurston/Schramm theorem assigns a conformally rigid fi-nite circle packing to a convex polyhedron, and then successive inversions yield a conformally rigid infin
From playlist Mathematics
Why the unit circle is so helpful for us to evaluate trig functions
👉 Learn about the unit circle. A unit circle is a circle which radius is 1 and is centered at the origin in the cartesian coordinate system. To construct the unit circle we take note of the points where the unit circle intersects the x- and the y- axis. The points of intersection are (1, 0
From playlist Trigonometric Functions and The Unit Circle
Circle Theorems Proof #1: Diameter & Chords - Higher GCSE Maths Help
Welcome to our first episode on circle theorems proofs! Proving circle theorems is a great exercise in reasoning, geometry, algebra and forming equations for all higher GCSE maths and IGCSE maths students! Proving circle theorems probably comes in at around level 7 or 8, but offers a grea
From playlist All Circle Theorems, Proofs & Exam Style Questions | Higher GCSE Maths Revision
A covering of a topological space X is a topological space Y together with a continuous surjective map from X to Y that is locally bi-continuos. The infinite spiral is for example a covering of the circle. Notice how every path on the circle can be lifted to the spiral. If a coveri
From playlist Algebraic Topology
How to quickly write out the unit circle
👉 Learn about the unit circle. A unit circle is a circle which radius is 1 and is centered at the origin in the cartesian coordinate system. To construct the unit circle we take note of the points where the unit circle intersects the x- and the y- axis. The points of intersection are (1, 0
From playlist Evaluate Trigonometric Functions With The Unit Circle (ALG2)
Quickly fill in the unit circle by understanding reference angles and quadrants
👉 Learn about the unit circle. A unit circle is a circle which radius is 1 and is centered at the origin in the cartesian coordinate system. To construct the unit circle we take note of the points where the unit circle intersects the x- and the y- axis. The points of intersection are (1, 0
From playlist Trigonometric Functions and The Unit Circle
Circle Theorems GCSE Maths Past Paper Exam Questions
A selection of circle theorems questions from Higher GCSE 9-1 maths past papers! These circle theorems questions vary in difficulty and involve use of the alternate segment theorem, proving a circle theorem, angles in the same segment and a cyclic quadrilateral. For all of my circle theo
From playlist CIRCLE THEOREMS GCSE 9-1 Maths Past Paper Exam Questions
How to memorize the unit circle
👉 Learn about the unit circle. A unit circle is a circle which radius is 1 and is centered at the origin in the cartesian coordinate system. To construct the unit circle we take note of the points where the unit circle intersects the x- and the y- axis. The points of intersection are (1, 0
From playlist Evaluate Trigonometric Functions With The Unit Circle (ALG2)
Apollonian packings and the quintessential thin group - Elena Fuchs
Speaker: Elena Fuchs (UIUC) Title: Apollonian packings and the quintessential thin group Abstract: In this talk we introduce the Apollonian group, sometimes coined the “quintessential” thin group, which is the underlying symmetry group of Apollonian circle packings. We review some of the e
From playlist My Collaborators
Geometry and arithmetic of sphere packings - Alex Kontorovich
Members' Seminar Topic: Geometry and arithmetic of sphere packings Speaker: A nearly optimal lower bound on the approximate degree of AC00 Speaker:Alex Kontorovich Affiliation: Rutgers University Date: October 23, 2017 For more videos, please visit http://video.ias.edu
From playlist Mathematics
Thin Groups and Applications - Alex Kontorovich
Analysis and Beyond - Celebrating Jean Bourgain's Work and Impact May 21, 2016 More videos on http://video.ias.edu
From playlist Analysis and Beyond
Apollonian circle packings via spectral methods - Hee Oh (Yale University)
notes for this talk: https://docs.google.com/viewer?url=http://www.msri.org/workshops/652/schedules/14556/documents/1680/assets/17222 Effective circle count for Apollonian circle packings, via spectral methods Hee Oh Brown University We will describe a recent effective counting result f
From playlist Number Theory
Diophantine analysis in thin orbits - Alex Kontorovich
Special Seminar Topic: Diophantine analysis in thin orbits Speaker: Alex Kontorovich Affiliation: Rutgers University; von Neumann Fellow, School of Mathematics Date: December 8, 2017 For more videos, please visit http://video.ias.edu
From playlist Mathematics
Alex Kontorovich - Diophantine problems in thin orbits
Diophantine problems in thin orbits
From playlist 28ème Journées Arithmétiques 2013
Jessica Purcell - Lecture 2 - Fully augmented links and circle packings
Jessica Purcell, Monash University Title: Fully augmented links and circle packings Fully augmented links form a family of hyperbolic links that are a playground for hands-on hyperbolic geometry. In the first part of the talk, I’ll define the links and show how to determine their hyperboli
From playlist 39th Annual Geometric Topology Workshop (Online), June 6-8, 2022
Alex Kontorovich - On the Strong Density Conjecture for Apollonian Circle Packings [2012]
slides for this talk: https://docs.google.com/viewer?url=http://www.msri.org/workshops/652/schedules/14560/documents/1681/assets/17223 Abstract: The Strong Density Conjecture states that for a given primitive integral Apollonian circle packing, every sufficiently large admissible (passing
From playlist Number Theory
Derive the Area of a Circle Using Integration (x^2+y^2=r^2)
This video explains how to derive the area formula for a circle using integration. http://mathispower4u.com
From playlist Applications of Integration: Arc Length, Surface Area, Work, Force, Center of Mass
STPM - Local to Global Phenomena in Deficient Groups - Elena Fuchs
Elena Fuchs Institute for Advanced Study September 21, 2010 For more videos, visit http://video.ias.edu
From playlist Mathematics
Given the radius and the center determine the equation of a circle
Learn how to write the equation of a circle. A circle is a closed shape such that all points are equidistance (equal distance) from a fixed point. The fixed point is called the center of the circle while the distance between any point of the circle and the center of the circle is called th
From playlist Circles