Configurations and point-line incidences

• 
  Two constructions of a harmonic quadrilateral
• 
  Suboptimal no-3-in-line placement by the method of Erdős
• 
  Dual arrangement to a regular pentagon
• 
  Rota's basis conjecture
• 
  Rota's basis conjecture
• 
  Vámos matroid
• 
  Möbius–Kantor configuration
• 
  Cremona–Richmond configuration
• 
  Reye configuration
• 
  Perles configuration
• 
  Hesse configuration
• 
  Hjelmslev's theorem
• 
  Schläfli double six
• 
  The Gray configuration
• 
  Non-Desargues configuration
• 
  Möbius–Kantor configuration
• 
  Complete quadrangle and dual complete quadrilateral
• 
  Desargues configuration as two mutually inscribed pentagons
• 
  No-three-in-line problem
• 
  Point sets with fewer than n/2 ordinary lines

Geometric graph theory

• 
  Grid bracing and its graph-theoretic analysis
• 
  Flexibility of an unbraced square grid in the grid bracing problem
• 
  Convex drawing
• 
  Greedy geometric spanner with distance ratio 1.1
• 
  Greedy geometric spanner with distance ratio 2
• 
  Triangle-free penny graph
• 
  Penny graph
• 
  The smallest cubic matchstick graph
• 
  Integral Fáry embedding of the octahedron
• 
  Indifference graph
• 
  Forbidden induced subgraphs of indifference graphs
• 
  Slope number of the Petersen graph
• 
  Slope number of bounded-degree planar graphs
• 
  Power diagram
• 
  Gabriel graph
• 
  Relative neighborhood graph
• 
  β-skeleton
• 
  Empty regions for the β-skeleton
• 
  String graph representation of a planar graph
• 
  An Erdős-Diophantine graph
• 
  Ageev's 5-chromatic circle graph
• 
  A circular-arc graph
• 
  A bitonic tour
• 
  An intersection graph of rectangles, with boxicity two.
• 
  Unit disk graph.
• 
  Hadwiger–Nelson problem: 7-coloring of the plane and 4-chromatic unit distance graph. From the junkyard.
• 
  A 3-colored triangulation for Fisk's proof of the art gallery theorem. From my WG09 slides.

Cayley graphs and symmetric graphs

• 
  Torus embedding of the order-13 Paley graph
• 
  The Johnson graph J(4,2)
• 
  ${\displaystyle K_{6}}$ drawn with three crossings
• 
  The smallest zero-symmetric graph with only two edge orbits
• 
  The graph of the 3-3 duoprism
• 
  Paley graph of order 9 and one of its triangles
• 
  7-vertex antihole graph
• 
  K₅ subdivision of a crown graph illustrating the Kelmans–Seymour conjecture
• 
  Hamiltonian decomposition
• 
  Oberwolfach problem
• 
  Distinguishing coloring of a 6-key keyring (6-vertex cycle graph)
• 
  distinguishing coloring of a hypercube
• 
  1-planar 8-crossing Nauru graph
• 
  Hamiltonicity of the truncated octahedral graph
• 
  18-vertex zero-symmetric graph
• 
  The unique edge coloring of G(9,2)
• 
  12-vertex crown graph
• 
  Perfect matchings in a complete graph, or chord diagrams
• 
  K₅ and K_3,3 as minors of the Petersen graph
• 
  K_2,2,2,2 as a 1-planar graph
• 
  Kuratowski subgraph
• 
  Cycle and its complement
• 
  Matchings in a complete 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
• 
  K_3,3 with each of its three color classes drawn as parallel line segments on distinct lines
• 
  Edge coloring of a complete graph
• 
  The Clebsch graph
• 
  Construction of the Clebsch graph from a hypercube
• 
  One-crossing 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 O₄
• 
  Pappus graph
• 
  Brinkmann graph
• 
  3-crossing drawing of the Heawood graph
• 
  The Petersen graph and its complement
• 
  The Nauru graph drawn as a unit distance graph
• 
  The intersection graph of the faces of a cube
• 
  Toroidal Nauru graph
• 
  Genus-4 Nauru graph
• 
  Crown graphs
• 
  The Wagner graph
• 
  The Petersen graph as a Kneser graph
• 
  The Shrikhande graph embedded on a torus.
• 
  The Gray graph.
• 
  The Folkman graph.
• 
  A permutohedron.
• 
  The Möbius–Kantor graph as a unit distance graph.
• 
  The Möbius–Kantor graph embedded symmetrically on a torus.
• 
  The cube-connected 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 M₁₆
• 
  The De Bruijn graph as a line graph
• 
  Three-dimensional binary De Bruijn graph
• 
  Paley graph, of order 13, as a circulant
• 
  Desargues graph

Dessins d'enfants

• 
  A dessin d'enfant
• 
  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)=x⁶
• 
  Two conjugate dessins d'enfants

Miscellaneous graph theory and graph drawing

• 
  Graphs with a universal vertex
• 
  Optimal coloring of a split graph
• 
  15-vertex planted clique in 32-vertex random graph
• 
  18-vertex planted clique in 64-vertex random graph
• 
  A graph of cutwidth 2
• 
  K₅ triangle packing and covering
• 
  The 2-core of a graph
• 
  The diamond graph and its line graph
• 
  Petersen minor in the flower snark
• 
  A bipartite graph and its line graph
• 
  Complementary perfect graphs
• 
  The Fritsch graph and its dual map
• 
  26-fullerene graph with distance labels
• 
  Unit distance graph with 16 vertices and 40 edges
• 
  Giant component
• 
  Universal vertex
• 
  Dominated vertex
• 
  Tree with 480 symmetries, example for Jordan–Pólya number
• 
  Feedback arc set NP-completeness
• 
  Feedback arc set
• 
  3-colorings of a square, up to symmetry
• 
  Shuffle-exchange network
• 
  3-colorings of a path graph
• 
  Hamiltonian path in the Herschel graph
• 
  Medial graph of the Herschel graph
• 
  Linear arboricity
• 
  Example for Grötzsch's theorem
• 
  Barnette–Bosák–Lederberg graph
• 
  King's graph
• 
  The densest possible planar locally linear graphs
• 
  Sudoku graph
• 
  Layers of a planar drawing of the graph of a rhombic dodecahedron
• 
  Illustration for the proof of Ore's theorem
• 
  Hamiltonian cycle in which nonadjacent pairs of vertices have degrees summing to at least n, for Ore's theorem
• 
  Szymanski's conjecture
• 
  Sumner's conjecture
• 
  Sum coloring
• 
  Zero-divisor graph
• 
  Lombardi drawing of the Golomb graph
• 
  The extension property of the Rado graph
• 
  Xuong tree
• 
  Graphic matroid parity
• 
  Graph-encoded map
• 
  Ribbon graph
• 
  Half graph
• 
  Hypertree
• 
  Tangled Kempe chains in the Errera graph
• 
  Tangled Kempe chains in the Poussin graph
• 
  Poussin graph
• 
  3-leaf power
• 
  Clique-width construction
• 
  A Halin graph without any 8-cycles
• 
  Map graph
• 
  Turán's brick factory problem
• 
  Acyclic orientations
• 
  Topological ordering
• 
  Transitive closure
• 
  Condensation
• 
  Pagewidth
• 
  Book crossing number
• 
  Split decomposition
• 
  An equilibrium stress
• 
  Scorpion graph
• 
  Self-dual graph
• 
  Isospectral enneahedra
• 
  Bidirected graph features
• 
  A 2-degenerate graph and its 2-core
• 
  Crossing number and 1-planarity of Tietze's graph
• 
  Tietze's graph on a Möbius strip
• 
  RAC drawing
• 
  Rainbow coloring of a wheel graph
• 
  Book embedding
• 
  Nonisomorphic planar duals
• 
  A line perfect graph
• 
  Partition of a line graph into cliques
• 
  Zarankiewicz problem
• 
  strangulated graph
• 
  dominance drawing
• 
  An upward planar drawing
• 
  A planar DAG that is not upward planar
• 
  Tutte embedding
• 
  Nested triangles graph
• 
  Grid drawing of nested triangles graph
• 
  Linear embedding
• 
  Euler tour of a tree
• 
  Unordered binary trees with four leaves
• 
  Fleischner's theorem
• 
  Square of a graph
• 
  Vertex-face coloring
• 
  Henneberg construction
• 
  Skew partition
• 
  Tree-depth
• 
  Gallai–Hasse–Roy–Vitaver theorem
• 
  A bramble in a 3x3 grid graph
• 
  Grinberg's non-Hamiltonian 5-cyclic-edge-connected 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 3-regular 1-connected well-covered graph
• 
  3-regular 3-connected well-covered graphs
• 
  A well-covered graph
• 
  A multigraph that has degree six, edge multiplicity three, and requires nine colors in any edge coloring
• 
  A 3-regular planar graph that requires four colors in any edge coloring
• 
  Hajós construction
• 
  An Apollonian network
• 
  Graph toughness
• 
  The Frucht graph in Lombardi drawing style
• 
  The Chvátal graph in Lombardi style
• 
  A block graph
• 
  A trivially perfect graph
• 
  An apex graph
• 
  Robertson's irreducible apex graph
• 
  The Petersen family
• 
  The Herschel graph
• 
  Planar separator for a grid graph
• 
  Forbidden minors for branchwidth three
• 
  Branch-decomposition
• 
  Chvátal graph
• 
  A caterpillar tree
• 
  Forbidden minors for pathwidth 1
• 
  Maximal independent sets
• 
  Domination in a product of stars, for Vizing's conjecture
• 
  Subdivision of K₅
• 
  The Goldner–Harary graph
• 
  The Herschel graph
• 
  A Halin graph
• 
  Forming a Schlegel diagram from shadows and light
• 
  The Rado graph
• 
  An equitable coloring
• 
  A cycle double cover of the Petersen graph
• 
  A Fibonacci cube
• 
  Finding matchings in claw-free graphs
• 
  An augmenting path in a claw-free graph
• 
  A simplex graph
• 
  A forbidden subgraph for comparability graphs
• 
  A factor-critical graph
• 
  Thomassen's girth-3 hypohamiltonian graph
• 
  A hypohamiltonian graph
• 
  Hadwiger's conjecture
• 
  A clique-sum
• 
  A distance-hereditary graph
• 
  Construction of a distance-hereditary graph
• 
  An implication graph
• 
  The median graph representing the set of solutions to a 2-satisfiability instance
• 
  A squaregraph
• 
  Converting a triangle-free graph into a median graph.
• 
  The Buneman graph, a median graph representing maximum-parsimony evolutionary relationships.
• 
  The retraction of a cube onto a median graph.
• 
  The median of three vertices in a median graph.
• 
  The median of three vertices in a tree.
• 
  A cograph described by a cotree.
• 
  A forbidden subgraph for the line graphs of hypergraphs
• 
  A self-complementary graph
• 
  Forbidden minors for partial 3-trees.
• 
  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.
• 
  A functional graph.
• 
  The butterfly and diamond, forbidden minors for pseudoforests.
• 
  A pseudoforest.
• 
  The Erdős–Faber–Lovász conjecture.
• 
  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 5-cycle is four
• 
  Wheel graphs with 4 to 9 vertices.
• 
  Beineke's nine forbidden line graphs.
• 
  Series-parallel graph.
• 
  Split graph.
• 
  The rooted product of graphs.
• 
  The lexicographic product of graphs.
• 
  The tensor product of graphs.
• 
  The cartesian product of graphs.
• 
  Partition of the torus into seven mutually adjacent regions, for Heawood conjecture.
• 
  Cactus graph
• 
  The Grötzsch graph.
• 
  König's theorem proof
• 
  König's theorem example
• 
  Erdős–Gyárfás conjecture, Markström's 4- and 8-cycle-free graph
• 
  The Grötzsch graph as the Mycielskian of a 5-cycle graph.

Miscellaneous geometry

• 
  Polyhedral dissection of the errera graph
• 
  Symmetries of quadrilaterals
• 
  Two square-counting puzzles
• 
  Chazelle polyhedron
• 
  Closed geodesics on nets for the triaugmented triangular prism
• 
  Tree-like curve
• 
  A midsquare quadrilateral and its midsquare
• 
  Squares having as diagonals the opposite sides of a midsquare quadrilateral
• 
  Binary tiling asymmetry
• 
  Binary tiling dual
• 
  Density in the binary tiling
• 
  Geometric structure of M. C. Escher's Regular Division of the Plane VI
• 
  Polygon with no exposed ears
• 
  Pythagorean dense rational distance set
• 
  Stereographic projection of an spherical octahedron and its associated circle packing
• 
  Illustration for a proof of the Erdős–Anning theorem
• 
  Grid points within a convex polygon
• 
  Polygonalizations of a 3x3 grid
• 
  Boscovich's cardioid
• 
  Intersections of a line with a convex curve
• 
  Decagon simplicial arrangement
• 
  Convex curve
• 
  Three circles associated with an antiparallelogram
• 
  Tangent circles to the extended sides of an antiparallelogram
• 
  Two circles tangent to the extended sides of a non-convex kite
• 
  The inscribed circle and ex-tangential circle of a kite
• 
  A kite and its dual isosceles trapezoid
• 
  Triaugmented triangular prism net
• 
  Triaugmented triangular prism
• 
  A fractal rosette of Penrose kites
• 
  Unflippable polygon
• 
  16 polygonalizations of a set of six points
• 
  Planar double bubbles
• 
  Crease pattern for Schwarz lantern
• 
  Empty regions for the Euclidean minimum spanning tree
• 
  Mrs. Miniver's problem
• 
  Two perpendicular quadrisections of a triangle
• 
  Geometry of pentagons in the dual snub square tiling
• 
  Zone in an arrangement of lines
• 
  Maximum in-radius isosceles triangle
• 
  Translucent Jessen icosahedron
• 
  Greek cross to rectangle dissection
• 
  Lifted frustum
• 
  Two orthogonal polyhedra
• 
  Fractal opaque set for a square
• 
  Opaque forests for a circle
• 
  7 disks can cover a single disk of twice the radius
• 
  Triangulating a grid polygon with primitive triangles
• 
  Tiling the plane with primitive triangles
• 
  Distance contours in a square grid
• 
  81 grid points in a radius-5 circle
• 
  Crossed lines method for curves of constant width
• 
  Comparison of Blichfeldt's theorem with Minkowski's theorem
• 
  Blichfeldt's theorem
• 
  Collinear form of Cairo pentagonal tiling
• 
  Equilateral form of Cairo pentagonal tiling
• 
  Reuleaux triangle and its middle hedgehog
• 
  Curve of constant width based on a semi-ellipse
• 
  Tresillo rhythm as a polygon
• 
  Ring lemma
• 
  Relative convex hull
• 
  Convex hull of a simple polygon
• 
  Net for Jessen's icosahedron
• 
  Jessen's icosahedron
• 
  Convex curve through 13 grid points
• 
  Danzer set
• 
  Isosceles set
• 
  Partition of a cyclic pentagon into isosceles triangles
• 
  4-hexagon net for an octahedron
• 
  Binary tiling
• 
  Partitions of a square into similar rectangles
• 
  Simplicial depth
• 
  Fermat's right triangle theorem
• 
  Ordinary lines
• 
  Moss's Egg
• 
  Maxima of a point set
• 
  Osgood curve
• 
  Ambiguity in network curve-shortening
• 
  Self-similar lens shape under curve-shortening
• 
  Curve-shortening of a convex curve
• 
  The grim reaper curve
• 
  Supporting lines of a Reuleaux triangle
• 
  Polyhedral Delta-Y transformations
• 
  Visual proof of Balinski's theorem
• 
  Non-convex pentagonal tiling
• 
  Non-convex pentagonal tiling
• 
  Farthest-first traversal
• 
  The Reuleaux triangle in a cluster of four soap bubbles
• 
  Langley’s Adventitious Angles
• 
  Orthocentroidal circle
• 
  Barrier resilience
• 
  Euclid XIII.10
• 
  Midpoint-stretching polygon
• 
  Heesch's anisohedral tiling
• 
  Viète's formula
• 
  ε-net
• 
  Heilbronn triangle problem
• 
  89th stage of toothpick sequence
• 
  Biggest little hexagon
• 
  Overlaid Pythagorean tilings
• 
  de Longchamps point
• 
  Coloring argument for De Bruijn's theorem
• 
  Non-harmonic packing for De Bruijn's theorem
• 
  Reuleaux kite
• 
  Equidiagonal quadrilateral
• 
  Circles meeting at the isodynamic point
• 
  Construction of the isodynamic point
• 
  Compound of three octahedra
• 
  Automedian triangle
• 
  Subdivisions of a pentagon
• 
  An orthodiagonal quadrilateral
• 
  British flag theorem
• 
  Pythagorean dissections
• 
  Similarity tiling by Koch snowflakes
• 
  Aperiodic section of the Pythagorean tiling
• 
  Tiling of the plane by shifted squares
• 
  Nearest neighbor graph
• 
  Theil–Sen estimator
• 
  Kawasaki's theorem
• 
  Midsphere
• 
  Inner radius
• 
  Shapley–Folkman lemma
• 
  Skew lines on nested hyperboloids
• 
  Tverberg's theorem
• 
  Radon's theorem
• 
  Helly's theorem
• 
  The Hadwiger conjecture in combinatorial geometry
• 
  The Schönhardt polyhedron.
• 
  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 3-4-5 right triangle.
• 
  Four levels of the Z-curve
• 
  Z-curve via interleaved binary coordinates
• 
  The Brocard point of a triangle
• 
  Intersecting planes
• 
  Chao's characterization of tangential quadrilaterals
• 
  A tangential quadrilateral
• 
  Convex layers and a halfspace. For an example in fractional cascading.
• 
  A Vietoris–Rips complex.
• 
  Happy Ending problem, eight points with no pentagon
• 
  Orthogonal convex hull and tight span.
• 
  Pseudotriangles.
• 
  The Szilassi polyhedron. From the junkyard.
• 
  A point quadtree.
• 
  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.
• 
  Convex shelling.
• 
  Happy Ending problem, quadrilaterals in five-point sets.
• 
  Pitteway triangulation
• 
  K-sets
• 
  H tree
• 
  Erdős–Szekeres theorem, geometric interpretation as monotone path

Number theory and combinatorics

• 
  Gomory's theorem on domino tiling mutilated chessboards
• 
  A chessboard region with no domino tiling but equal colors
• 
  Lambek–Moser theorem for prime numbers
• 
  Lambek–Moser theorem
• 
  Dyadic approximation of ${\displaystyle {\sqrt {2}}}$
• 
  Numbers without unusually-accurate dyadic approximations
• 
  Salem–Spencer set
• 
  Relative error of approximations to the prime-counting function
• 
  Primes vs composites
• 
  Growth rate of the Moser–de Bruijn sequence
• 
  Addition of numbers in the Moser–de Bruijn sequence
• 
  Gould's sequence
• 
  A cap set
• 
  Bijection between binary trees and stack-sortable permutations
• 
  Congruum
• 
  Lower bound construction for the Erdős–Ko–Rado theorem
• 
  Centered octahedral number
• 
  Centered cube number
• 
  Two right triangles, with one hypotenuse the square of the other
• 
  Trees counted by the Wedderburn–Etherington numbers
• 
  Sauer–Shelah lemma
• 
  Levi's lemma
• 
  Dickson's lemma applied to the hyperbola xy ≥ 9
• 
  Trees counted by the ordered Bell numbers
• 
  Rank of a partition
• 
  Pell's equation
• 
  Gaussian moat
• 
  Stella octangula number
• 
  Representation of octahedral numbers as centered square pyramids
• 
  Octahedral number
• 
  Squares in a square
• 
  Calkin–Wilf sequence
• 
  Calkin–Wilf tree
• 
  15=4+5+6 is a polite number
• 
  Dyadic rationals
• 
  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.
• 
  Square pyramidal number.
• 
  Rational approximations to the octagon from Pell numbers.
• 
  Integer right triangles with nearly-equal legs from Pell numbers.
• 
  Divisibility of regular numbers.

Order theory

• 
  2-dimensional modular lattice
• 
  Dedekind–MacNeille completion
• 
  A fence
• 
  The extreme case for the 1/3–2/3 conjecture
• 
  A series-parallel partial order
• 
  A semiorder
• 
  Free distributive lattice of monotonic Boolean functions.
• 
  Young–Fibonacci lattice.
• 
  Young's lattice.
• 
  Example for Birkhoff's representation theorem.
• 
  A Tamari lattice.
• 
  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 Dih₄.
• 
  A concept lattice.
• 
  Three views of an antimatroid.

Cellular automata

• 
  Anneal
• 
  1d reversible CA defined from a rectangular band
• 
  Critters transition rule
• 
  Toothpick sequence
• 
  Rule 90 gate array
• 
  Trees in Rule 90
• 
  Critters
• 
  Block cellular automaton
• 
  Day & Night, Bell's p256 butterfly gun
• 
  One-dimensional cyclic cellular automaton.
• 
  Two-dimensional cyclic cellular automaton.
• 
  puffer train.
• 
  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.
• 
  Rule 184

Algorithms and data structures

• 
  Binary tree from random insertions
• 
  Uniformly random binary tree
• 
  Extended binary tree
• 
  Random binary trees
• 
  Pinwheel scheduling
• 
  Finding the median of 5 values in 6 comparisons
• 
  X + Y sorting
• 
  Garsia–Wachs algorithm
• 
  Boyer–Moore majority vote algorithm
• 
  Another SPQR tree
• 
  Reduction from 3SAT to 3-coloring
• 
  Prefix sum
• 
  An SPQR tree.
• 
  Consecutive pairs that bracket x in a sequence, for the Cartesian tree article
• 
  A Cartesian tree
• 
  Using a Cartesian tree for range searching
• 
  Johnson's algorithm
• 
  Floyd's "tortoise and hare" cycle detection algorithm.
• 
  Bloom filter

Topology

• 
  Pentagonal Möbius strip
• 
  5-vertex polyhedral Möbius strip
• 
  6-vertex polyhedral strip with triangular boundary
• 
  Level sets of a cross-cap
• 
  Symmetric Whitehead link
• 
  Six-component "rubberband" Brunnian link
• 
  Algebraic link diagram for the Borromean rings
• 
  Hedgehog space
• 
  Trefoil with bridge number 2
• 
  square ribbon knot
• 
  A train track on a triple torus.
• 
  A switch in a train track.

Miscellaneous

• 
  Monotone piecewise linear function
• 
  Fokker periodicity blocks
• 
  Combinatorial equivalence between plane trees, polygon subdivisions, and parenthesizations
• 
  A Langford pairing
• 
  Pitch class space
• 
  Descriptive chess notation
• 
  Binary erasure channel
• 
  Binary symmetric channel
• 
  Diagram for a triangulated category
• 
  academic genealogy of Johannes De Groot and his namesake

Mendocino County

• 
  Big River, Mendocino, California
• 
  Russian Gulch State Park and the Frederick W. Panhorst Bridge
• 
  Little River beach
• 
  Ten Mile River
• 
  Cleone
• 
  Cleone Groceries
• 
  Albion River
• 
  Albion River Bridge
• 
  Navarro River Redwoods State Park
• 
  Hendy Woods State Park
• 
  Jug Handle Beach
• 
  Comptche
• 
  Montgomery Woods
• 
  Virgin Creek
• 
  Mendocino Beacon building

Orange County

• 
  Bridge across North Lake, Woodbridge, Irvine, California
• 
  Balboa Island Ferry
• 
  California State Route 73
• 
  University Hills, Irvine, California
• 
  Vista Verde School
• 
  Bren Hall at UCI
• 
  Social Ecology at UCI
• 
  Science Plaza at UCI
• 
  Orange County Museum of Art
• 
  San Joaquin Wildlife Sanctuary
• 
  San Joaquin Wildlife Sanctuary

Theoretical computer scientists

• 
  Dan Hirschberg
• 
  Knuth Prize presentation to Volker Strassen
• 
  Volker Strassen giving the Knuth Prize lecture
• 
  János Pach
• 
  Graph Drawing 2009
• 
  Timothy M. Chan
• 
  Ken Clarkson
• 
  Joe Mitchell
• 
  Herbert Edelsbrunner
• 
  Ileana Streinu
• 
  Peter Eades
• 
  Frank Ruskey
• 
  Sue Whitesides
• 
  Bruce Reed
• 
  Jörg Sack
• 
  Faith Ellen
• 
  David Kirkpatrick
• 
  Diane Souvaine
• 
  Stefan Langerman
• 
  Vijay Vazirani

Wall poems in Leiden

Miscellaneous

• 
  Lisa Fernandez
• 
  "Balancing", by John Hooper
• 
  Die Roten Punkte
• 
  Campbell Hall, UIUC
• 
  CICESE
• 
  CIMAT