Unsolved problems in graph theory | Strongly regular graphs

Conway's 99-graph problem

In graph theory, Conway's 99-graph problem is an unsolved problem asking whether there exists an undirected graph with 99 vertices, in which each two adjacent vertices have exactly one common neighbor, and in which each two non-adjacent vertices have exactly two common neighbors. Equivalently, every edge should be part of a unique triangle and every non-adjacent pair should be one of the two diagonals of a unique 4-cycle. John Horton Conway offered a $1000 prize for its solution. (Wikipedia).

Conway's 99-graph problem
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The 97 Math Problem

Can you fill up the blanks? I hope you enjoy this one, which is not that difficult, though. Next puzzle: http://www.youtube.com/watch?v=4e_TZW_UbM0 Solution: http://www.youtube.com/watch?v=tPLmbZAbWeI

From playlist Tricks and Math Puzzles

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Dizzying Divisors Problem from AOPS by the river!

We solve the Dizzying Divisors problem from AOPS (Art of Problem Solving)! We are asked to determine if there are any positive integers x and y so that the number of divisors of x^2+x+1 equals y^2+y+1. The problem is presented in terms of a function that outputs the number of divisors so t

From playlist Coffee Time Math with Wrath of Math

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20. Invariants problem 40

Here I solve just one problem, but the level of difficulty of the problem was such that I was quite pleased to get it. The book reveals that it is due to John Conway, so I knew that there had to be a lower bound on its difficulty, and that there would almost certainly be some beautiful sur

From playlist Thinking about maths problems in real time: mostly invariants problems

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GoGaRuCo 2013 - Ruby On Robots Using Artoo by Ron Evans

The robotics revolution has already begun. You can buy drones and robotic devices at local retail stores. Unfortunately, it's hard to develop code for robots, and nearly impossible to create solutions that integrate multiple different kind of devices. Introducing Artoo, a new robotics fram

From playlist GoGaRuCo 2013

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The 97 Math Problem solution

Question video: http://www.youtube.com/watch?v=0xO8w_uCo5M That was easy, wasn't it? I hope you enjoyed it. Next puzzle: http://www.youtube.com/watch?v=4e_TZW_UbM0

From playlist Tricks and Math Puzzles answers

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Fractran: A Ridiculous Logical Language with John Conway [2012]

John Conway is a prolific mathematician who researches the theory of finite groups, knot theory, number theory, combinatorial game theory and coding theory. He has also contributed to many branches of recreational mathematics, notably the invention of the cellular automaton called the Game

From playlist Mathematics

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Turing Machines and The Halting Problem (Part 2)

The Halting Problem has fascinated thousands of computer scientists from around the world. A major part of Computing Logic, the proof of the halting problem proves that computers can't do everything. Check out the video to learn more about why computers work the way they do! For Turing Ma

From playlist Math

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Remembering John Conway - Full Video

Bay Area Artists and Mathematicians - BAAM! with Gathering 4 Gardner - G4G present Remembering John Conway Mathematician John Horton Conway died of COVID-19 on April 11, 2020. On April 25th, the Bay Area Artists and Mathematicians (BAAM!) hosted an informal Zoom session to share memories

From playlist Tributes & Commemorations

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Round table on open problems in non-equilibrium statistical physics... - Michael Aizenmann

Michael Aizenmann Princeton University March 28, 2014 For more videos, visit http://video.ias.edu

From playlist Mathematics

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James Propp - Conjectural Enumerations of Trimer Covers of Finite Subgraphs of the Triangular (...)

The work of Conway and Lagarias applying combinatorial group theory to packing problems suggests what we might mean by “domain-wall boundary conditions” for the trimer model on the infinite triangular lattice in which the permitted trimers are triangle trimers and three-in-a-line trimers.

From playlist Combinatorics and Arithmetic for Physics: special days

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MATH1081 Discrete Maths: Chapter 1 Question 31

We look at a function f which is f(m,n)=mn for m and n are positive integers, and check that if f is one to one or onto. Presented by Peter Brown of the School of Mathematics and Statistics, Faculty of Science, UNSW.

From playlist MATH1081 Discrete Mathematics

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Remembering John Conway - Part 5

Bay Area Artists and Mathematicians - BAAM! with Gathering 4 Gardner - G4G present Remembering John Conway Mathematician John Horton Conway died of COVID-19 on April 11, 2020. On April 25th, the Bay Area Artists and Mathematicians (BAAM!) hosted an informal Zoom session to share memories

From playlist Tributes & Commemorations

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Remembering John Conway - Part 4

Bay Area Artists and Mathematicians - BAAM! with Gathering 4 Gardner - G4G present Remembering John Conway Mathematician John Horton Conway died of COVID-19 on April 11, 2020. On April 25th, the Bay Area Artists and Mathematicians (BAAM!) hosted an informal Zoom session to share memories

From playlist Tributes & Commemorations

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Remembering John Conway - Part 2

Bay Area Artists and Mathematicians - BAAM! with Gathering 4 Gardner - G4G present Remembering John Conway Mathematician John Horton Conway died of COVID-19 on April 11, 2020. On April 25th, the Bay Area Artists and Mathematicians (BAAM!) hosted an informal Zoom session to share memories

From playlist Tributes & Commemorations

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Braden Douglass - Breaking Up The Monolith With EQ | SolidusConf 2019

Braden Douglass breaks up the monolith. "Breaking Up The Monolith With EQ" Emotional intelligence is sometimes missing from the software engineering realm. However, how can we as engineers and managers utilize it when feeling the pain of a monolithic application design? How do EQ markers

From playlist SolidusConf 2019

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limits from a graph (all cases covered!)

In this video I go through all the cases of how to evaluate limits from a graph. This video is very comprehensive and should provide the viewer with the tools to evaluate limits from the graph of a function. The graphs used in this video involve removable discontinuities, jump discontinuit

From playlist Calculus 1

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Farmhouse Conf 4 Future Current: The Robot (R)Evolution by Ron Evans

This is a talk about robots. This is a talk about humanity. This is a talk about technology. This is a talk about evolution. This is a talk about the future. This is a talk about atemporality. This is a talk about robots. Help us caption & translate this video! http://amara.org/v/FG9v/

From playlist Farmhouse Conf 4

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A Maths Puzzle: Find the nine digit number

Find a nine digit numbers, using the numbers 1 to 9, and using each number once without repeats, such that; the first digit is a number divisible by 1. The first two digits is a number divisible by 2; The first three digits is a number divisible by 3 and so on until we get a nine digit num

From playlist My Maths Videos

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Jonathan Bobrow - How John Conway's Game of Life Inspired a Tabletop Game System - G4G14 Apr 2022

A 5 minute talk sharing the 7 year journey of studying emergent properties of cellular automata to accidentally inventing a game system. MIT Media Lab Alum and Founder of Move38, Jonathan Bobrow describes how making an open-source game system started as a small seed and has grown to a comm

From playlist G4G14 Videos

Related pages

3-3 duoprism | Graph theory | Regular graph | Danzer set | Sylver coinage | Vertex (graph theory) | Strongly regular graph | Thrackle | Locally linear graph | Paley graph | John Horton Conway