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

Aphrodite. Greek mythology. Sculpture. Aphrodite is the Greek goddess of love and beauty.

12 Greek Gods and Goddesses

Close-up of tobacco plants in Ontario, Canada. Tobacco, Nicotiana, cured leaves used after processing in various ways for smoking, snuffing, chewing, and extracting of nicotine.

7 of the World’s Deadliest Plants

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?

Ahura Mazda - relief of the Zoroastrian god Ahura Mazda at the ancient ruins of Persepolis in Iran. Also known as Ormazd Zoroastrianism,

Which Religion Is the Oldest?

American bison (Bison bison) also known as buffalo or plains buffalo on the prairie, western U.S.

What’s the Difference Between Bison and Buffalo?

Andrew Jackson delivering a speech while on his way to Washington, D.C., for his inauguration in 1829. From Harper's Weekly, 1881.

5 Remarkably Close U.S. Presidential Elections

The Cheshire Cat is a fictional cat from Lewis Carroll's Alice's Adventures in Wonderland. (Alice in Wonderland)

11 Banned Books Through Time

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 König’s theorem Latin square Ising problem Möbius inversion theorem necklace problem Ramsey’s numbers distinct representative orthogonal array set theory analysis probability theory cryptology computer science algebra statistics geometry automata theory information theory

Key People

Paul Erdős

Paul Erdős

Hungarian mathematician

Andrei Okounkov

Russian mathematician

Quiz

Equations written on blackboard

Numbers and Mathematics