combinatorics

Table of Contents

Introduction
History
- Early developments
- Combinatorics during the 20th century
Problems of enumeration
- Permutations and combinations
  - Binomial coefficients
  - Multinomial coefficients
- Recurrence relations and generating functions
- Partitions
- The Ferrer diagram
- The principle of inclusion and exclusion: derangements
- Polya’s theorem
- The Möbius inversion theorem
- Special problems
  - The Ising problem
  - Self-avoiding random walk
Problems of choice
- Systems of distinct representatives
- Ramsey’s numbers
Design theory
- BIB (balanced incomplete block) designs
- PBIB (partially balanced incomplete block) designs
Latin squares and the packing problem
- Orthogonal Latin squares
- Orthogonal arrays and the packing problem
Graph theory
- Definitions
- Enumeration of graphs
- Characterization problems of graph theory
Applications of graph theory
- Planar graphs
- The four-colour map problem
- Eulerian cycles and the Königsberg bridge problem
- Directed graphs
Combinatorial geometry
- Some historically important topics of combinatorial geometry
  - Packing and covering
  - Polytopes
  - Incidence problems
  - Helly’s theorem
- Methods of combinatorial geometry
  - Exhausting the possibilities
  - Use of extremal properties
  - Use of transformations between different spaces and applications of Helly’s theorem

References & Edit History Quick Facts & Related Topics

Images

Ferrers' partitioning diagram for 14

orthogonal Latin squares

two isomorphic graphs and a tree

two homeomorphic graphs A and B

two graphs important to planar properties

seven bridges of Königsberg and multigraph.

packing of disks

covering of part of a plane with triangles

prism and truncated pyramid

example of theorem on extremal properties

For Students

combinatorics summary

Discover

Mayer Amschel Rothschild (1744-1855), founder of the house of Rothschild; lithograph by Friedrich Lieder, c. 1830.

Where Do Anti-Semitic Conspiracy Theories About the Rothschild Family Come From?

Leonardo da Vinci (1452-1519), Italian Renaissance painter from Florence. Engraving by Cosomo Colombini (d. 1812) after a Leonardo self portrait. Ca. 1500.

10 Famous Artworks by Leonardo da Vinci

Close up of books. Stack of books, pile of books, literature, reading. Homepage 2010, arts and entertainment, history and society

12 Novels Considered the “Greatest Book Ever Written”

New York NY/ USA- November 23, 2018 Hordes of shoppers throng the Macy's Herald Square flagship store in New York looking for bargains on the day after Thanksgiving, Black Friday.

Why Is It Called Black Friday?

An ancient egyptian hieroglyphic painted carving showing the falcon headed god Horus seated on a throne and holding a golden fly whisk. Before him are the Pharoah Seti and the goddess Isis. Interior wall of the temple to Osiris at Abydos, Egypt.

11 Egyptian Gods and Goddesses

Diverse elementary school children wearing school uniforms running outside of school. Boys girls

Pro and Con: School Uniforms

Santa Claus flying in his sleigh, christmas, reindeer

Was Santa Claus a Real Person?

combinatorics: Facts & Related Content

Written and fact-checked by The Information Architects of Encyclopaedia Britannica

Facts

Also Known As	combinatorial mathematics

Photos

Ferrers' partitioning diagram for 14

orthogonal Latin squares

two isomorphic graphs and a tree

two homeomorphic graphs A and B

two graphs important to planar properties

seven bridges of Königsberg and multigraph.

packing of disks

covering of part of a plane with triangles

prism and truncated pyramid

example of theorem on extremal properties

See All Images →

Topics

graph theory permutations and combinations Möbius inversion theorem network theory recurrence relation combination Euler’s theorem on polyhedrons Hall’s theorem König’s theorem design analysis probability theory cryptology computer science algebra statistics geometry automata theory set theory information theory

Key People

Paul Erdős

Paul Erdős

Hungarian mathematician

Andrei Okounkov

Russian mathematician

Quiz

Equations written on blackboard

Numbers and Mathematics