### Top Posts

### Recent comments

- Ofir Gorodetsky on A little problem
- Ofir Gorodetsky on A little problem
- gorodetsky on A new constant?
- Ofir Gorodetsky on A little problem
- Peter Cameron on Andrzej Orchel

### Blogroll

- Alexander Konovalov
- Annoying precision
- Astronomy Picture of the Day
- Azimuth
- Bad science
- Bob Walters
- British Combinatorial Committee
- CIRCA tweets digest
- CoDiMa
- Coffee, love, and matrix algebra
- Collecting reality
- Comfortably numbered
- Computational semigroup theory
- DC's Improbable Science
- Diamond Geezer
- Exploring East London
- From hill to sea
- Gödel's lost letter and P=NP
- Gil Kalai
- Haris Aziz
- Intersections
- Jane's London
- Jon Awbrey
- Kourovka Notebook
- LMS blogs page
- Log24
- London Algebra Colloquium
- London Reconnections
- Marie Cameron's blog
- MathBlogging
- Micromath
- Neill Cameron
- neverendingbooks
- Noncommutative geometry
- numericana hall of fame
- Paul Goldberg
- Ratio bound
- Robert A. Wilson's blog
- Sheila's blog
- Since it is not …
- Spitalfields life
- St Albans midweek lunch
- Stubborn mule
- Sylvy's mathsy blog
- SymOmega
- Tangential thoughts
- Terry Tao
- The Aperiodical
- The De Morgan Journal
- The ICA
- The London column
- The Lumber Room
- The matroid union
- Theorem of the day
- Tim Gowers
- Vynmath
- XKCD

### Find me on the web

### Cameron Counts: RSS feeds

### Meta

# Tag Archives: Petersen graph

## Aliens Do Exist

The people from the planet Ade have intercepted radio transmissions from Earth, and have discovered that we know about the Petersen graph and the root system E6. One day, a flying saucer from Ade arrives on Earth and delivers an … Continue reading

Posted in doing mathematics, events
Tagged Petersen graph, random graph, root systems, Sira Gratz, University of Leeds
1 Comment

## A small fact about the Petersen graph

The Petersen graph has 10 vertices and 15 edges, and the complete graph on 10 vertices has 45 edges. However, Allen Schwenk and (independently) O. P. Lossers (Jack van Lint’s problem-solving seminar in Eindhoven) showed that you can’t partition the … Continue reading

## A puzzle for you

The Petersen graph is perhaps the most famous graph of all. It has ten vertices, fifteen edges, valency 3, and no triangles. Since the complete graph on ten vertices has 45 edges and valency 9, one might ask whether the … Continue reading

## Counting colourings of graphs

Every graph theorist knows that the colourings of a graph with a given number of colourings are counted by a certain polynomial, the chromatic polynomial of the graph. My purpose here is to point out that there is more to … Continue reading

Posted in exposition, open problems
Tagged acyclic orientations, Inclusion-Exclusion, orbit-counting lemma, Petersen graph
1 Comment