User:David Eppstein/Gallery
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Contents
 1 Mathematical illustrations
 1.1 Configurations and pointline incidences
 1.2 Geometric graph theory
 1.3 Cayley graphs and symmetric graphs
 1.4 Dessins d'enfants
 1.5 Miscellaneous graph theory and graph drawing
 1.6 Miscellaneous geometry
 1.7 Number theory and combinatorics
 1.8 Order theory
 1.9 Cellular automata
 1.10 Algorithms and data structures
 1.11 Miscellaneous
 2 Photography
 3 See also
Mathematical illustrations[edit]
I've placed most of the following mathematical illustrations in the public domain. If you see an illustration I've drawn for one of my other web sites, and want it to be uploaded to the commons for whatever reason, please ask by email: if I upload it myself, it can be more properly licensed, and it's likely that I still have the vectorized source instead of the rasterized version I use for web images.
Configurations and pointline incidences[edit]

NonDesargues configuration

Complete quadrangle and dual complete quadrilateral

Desargues configuration as two mutually inscribed pentagons

Point sets with fewer than n/2 ordinary lines
Geometric graph theory[edit]

Integral Fáry embedding of the octahedron

Slope number of the Petersen graph

Slope number of boundeddegree planar graphs

Empty regions for the βskeleton

String graph representation of a planar graph

Ageev's 5chromatic circle graph

An intersection graph of rectangles, with boxicity two.

Hadwiger–Nelson problem: 7coloring of the plane and 4chromatic unit distance graph. From the junkyard.

A 3colored triangulation for Fisk's proof of the art gallery theorem. From my WG09 slides.
Cayley graphs and symmetric graphs[edit]

12vertex crown graph

K_{5} and K_{3,3} as minors of the Petersen graph

K_{2,2,2,2} as a 1planar graph

Butterfly network as a multitree

Johnson graph J(5,2)

The Clebsch graph labeled as in a construction for Keller's conjecture

The path formed by the Steinhaus–Johnson–Trotter algorithm

Edge coloring of a complete graph

The Clebsch graph

Onecrossing drawing of K_{3,3}

A generalized Petersen graph with only three Hamiltonian cycles

The Shrikhande graph in Lombardi style

The Folkman graph in Lombardi style

The octahedron as pancyclic graph

The odd graph O_{4}

3crossing drawing of the Heawood graph

The Petersen graph and its complement

The Nauru graph drawn as a unit distance graph

Toroidal Nauru graph

Genus4 Nauru graph

The Petersen graph as a Kneser graph

The Shrikhande graph embedded on a torus.

The Gray graph.

The Möbius–Kantor graph as a unit distance graph.

The Möbius–Kantor graph embedded symmetrically on a torus.

The cubeconnected cycles of order 3.

The Paley graph of order 9 as a perfect graph.

The Petersen graph as a Moore graph.

Two views of the Möbius ladder graph M_{16}

The De Bruijn graph as a line graph

Threedimensional binary De Bruijn graph

Paley graph, of order 13, as a circulant
Dessins d'enfants[edit]

Transforming a dessin d'enfant into gluing instructions for a Riemann surface

The dessins d'enfants for the Chebyshev polynomials

The dessin d'enfant for the sextic monomial p(x)=x^{6}

Two conjugate dessins d'enfants
Miscellaneous graph theory and graph drawing[edit]

A 2degenerate graph and its 2core

Tietze's graph on a Möbius strip

Partition of a line graph into cliques

A bramble in a 3x3 grid graph

List coloring for K_{3,27}

Moser spindle as a pseudotriangulation

A planar Lombardi drawing of the Frucht graph

A Hamiltonian cycle in the Dürer graph

A multigraph that has degree six, edge multiplicity three, and requires nine colors in any edge coloring

A 3regular planar graph that requires four colors in any edge coloring

The Frucht graph in Lombardi drawing style

The Chvátal graph in Lombardi style

An apex graph

The Petersen family

The Herschel graph

Planar separator for a grid graph

Forbidden minors for branchwidth three

Domination in a product of stars, for Vizing's conjecture

Subdivision of K_{5}

The Herschel graph

Forming a Schlegel diagram from shadows and light

The Rado graph

A cycle double cover of the Petersen graph

Finding matchings in clawfree graphs

An augmenting path in a clawfree graph

A forbidden subgraph for comparability graphs

Construction of a distancehereditary graph

The median graph representing the set of solutions to a 2satisfiability instance

Converting a trianglefree graph into a median graph.

The Buneman graph, a median graph representing maximumparsimony evolutionary relationships.

The retraction of a cube onto a median graph.

The median of three vertices in a median graph.

A cograph described by a cotree.

A forbidden subgraph for the line graphs of hypergraphs

Forbidden minors for partial 3trees.

A graph and its tree decomposition.

An interval graph.

Partition of the complete bipartite graph K_{4,4} into three forests, showing that it has arboricity three.

The butterfly and diamond, forbidden minors for pseudoforests.

A pseudoforest.

A 4x4 grid graph and one of its spanning trees.

Fáry's theorem, induction step of proof

An aperiodic graph.

A graph that is not aperiodic as all cycles are divisible by three.

The Turán graph T(13,4).

Thue number of the 5cycle is four

Wheel graphs with 4 to 9 vertices.

Beineke's nine forbidden line graphs.

Partition of the torus into seven mutually adjacent regions, for Heawood conjecture.

The Grötzsch graph.

König's theorem proof

König's theorem example

Erdős–Gyárfás conjecture, Markström's 4 and 8cyclefree graph

The Grötzsch graph as the Mycielskian of a 5cycle graph.
Miscellaneous geometry[edit]

Heesch's anisohedral tiling

89th stage of toothpick sequence

Overlaid Pythagorean tilings

Coloring argument for De Bruijn's theorem

Nonharmonic packing for De Bruijn's theorem

Circles meeting at the isodynamic point

Construction of the isodynamic point

Similarity tiling by Koch snowflakes

Aperiodic section of the Pythagorean tiling

Skew lines on nested hyperboloids

A cube dissected into orthoschemes.

A Davenport–Schinzel sequence from a lower envelope of line segments

The Fermat–Apollonius circle of an ellipse.

The trisected perimeter point of a 345 right triangle.

Four levels of the Zcurve

Zcurve via interleaved binary coordinates

The Brocard point of a triangle

Intersecting planes

Chao's characterization of tangential quadrilaterals

Convex layers and a halfspace. For an example in fractional cascading.

Happy Ending problem, eight points with no pentagon

The Szilassi polyhedron. From the junkyard.

The face lattice of a square pyramid.

The Nagel point of a triangle.

The Philo line and its application to doubling the cube.

Heesch's problem, Amman's dented hexagon. From the junkyard.

Happy Ending problem, quadrilaterals in fivepoint sets.

Erdős–Szekeres theorem, geometric interpretation as monotone path
Number theory and combinatorics[edit]

Lower bound construction for the Erdős–Ko–Rado theorem

Trees counted by the Wedderburn–Etherington numbers

Dickson's lemma applied to the hyperbola xy ≥ 9

Trees counted by the ordered Bell numbers

15=4+5+6 is a polite number

Graphical demonstration of a solution to Znám's problem.

Graphical demonstration that 1 = 1/2 + 1/3 + 1/7 + 1/43 + ...; see Sylvester's sequence.

Rational approximations to the octagon from Pell numbers.

Integer right triangles with nearlyequal legs from Pell numbers.

Divisibility of regular numbers.
Order theory[edit]

A fence

The extreme case for the 1/3–2/3 conjecture

Example for Birkhoff's representation theorem.

The Hasse diagram of a distributive lattice.

Dilworth's theorem, transformation from chain decomposition to bipartite matching.

The 13 possible strict weak orderings on a set of three elements.

A partial order of dimension 4 and its realizer.

The lattice of subgroups of Dih_{4}.

Three views of an antimatroid.
Cellular automata[edit]

Rule 90 gate array

Trees in Rule 90

Day & Night, Bell's p256 butterfly gun

Onedimensional cyclic cellular automaton.

Twodimensional cyclic cellular automaton.

The space rake.

Rule 184 as a model of traffic flow.

Rule 184 as a model of deposition.

Rule 184 as a model of ballistic annihilation.
Algorithms and data structures[edit]

An SPQR tree.

Using a Cartesian tree for range searching

Floyd's "tortoise and hare" cycle detection algorithm.
Miscellaneous[edit]

Trefoil with bridge number 2

Diagram for a triangulated category

academic genealogy of Johannes De Groot and his namesake

A train track on a triple torus.

A switch in a train track.
Photography[edit]
Most of my photos here are licensed under Creative Commons Attribution ShareAlike. See Flickr for some of my other photos, and my web site for almost all of them; if it's not listed here, it's probably not yet publically licensed, but I may be willing to share anyway.
Mendocino County[edit]

Little River beach

Jug Handle Beach
Orange County[edit]

Bridge across North Lake, Woodbridge, Irvine, California
Theoretical computer scientists[edit]

Knuth Prize presentation to Volker Strassen

Volker Strassen giving the Knuth Prize lecture
Wall poems in Leiden[edit]
Miscellaneous[edit]

"Balancing", by John Hooper