Julius Peter Christian Petersen (16 June 1839, Sorø

Sorø

Sorø is a town in Sorø municipality in Region Sjælland on the island of Zealand in east Denmark. The population is 7,805 . The municipal council and the regional council are located in Sorø....

, West Zealand – 5 August 1910, Copenhagen

Copenhagen

Copenhagen is the capital and largest city of Denmark, with an urban population of 1,199,224 and a metropolitan population of 1,930,260 . With the completion of the transnational Øresund Bridge in 2000, Copenhagen has become the centre of the increasingly integrating Øresund Region...

) was a Danish

Denmark

Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...

 mathematician

Mathematician

A mathematician is a person whose primary area of study is the field of mathematics. Mathematicians are concerned with quantity, structure, space, and change....

.

Biography

Petersen's interests in mathematics were manifold (geometry

Geometry

Geometry arose as the field of knowledge dealing with spatial relationships. Geometry was one of the two fields of pre-modern mathematics, the other being the study of numbers ....

, function theory, number theory

Number theory

Number theory is a branch of pure mathematics devoted primarily to the study of the integers. Number theorists study prime numbers as well...

, mathematical physics

Mathematical physics

Mathematical physics refers to development of mathematical methods for application to problems in physics. The Journal of Mathematical Physics defines this area as: "the application of mathematics to problems in physics and the development of mathematical methods suitable for such applications and...

, mathematical economics

Mathematical economics

Mathematical economics is the application of mathematical methods to represent economic theories and analyze problems posed in economics. It allows formulation and derivation of key relationships in a theory with clarity, generality, rigor, and simplicity...

, cryptography

Cryptography

Cryptography is the practice and study of techniques for secure communication in the presence of third parties...

 and graph theory

Graph theory

In mathematics and computer science, graph theory is the study of graphs, mathematical structures used to model pairwise relations between objects from a certain collection. A "graph" in this context refers to a collection of vertices or 'nodes' and a collection of edges that connect pairs of...

).
His famous paper Die Theorie der regulären graphs was a fundamental contribution to modern graph theory as we know it today. In 1898, he presented a counterexample to Tait

Peter Guthrie Tait

Peter Guthrie Tait FRSE was a Scottish mathematical physicist, best known for the seminal energy physics textbook Treatise on Natural Philosophy, which he co-wrote with Kelvin, and his early investigations into knot theory, which contributed to the eventual formation of topology as a mathematical...

's claimed theorem about 1-factorability of 3-regular graphs, which is nowadays known as the "Petersen Graph

Petersen graph

In the mathematical field of graph theory, the Petersen graph is an undirected graph with 10 vertices and 15 edges. It is a small graph that serves as a useful example and counterexample for many problems in graph theory. The Petersen graph is named for Julius Petersen, who in 1898 constructed it...

".

He published a systematic treatment of geometrical

Geometry

Geometry arose as the field of knowledge dealing with spatial relationships. Geometry was one of the two fields of pre-modern mathematics, the other being the study of numbers ....

 constructions (with straightedge and compass) in 1880. A French

French language

French is a Romance language spoken as a first language in France, the Romandy region in Switzerland, Wallonia and Brussels in Belgium, Monaco, the regions of Quebec and Acadia in Canada, and by various communities elsewhere. Second-language speakers of French are distributed throughout many parts...

 translation was reprinted in 1990.

A special issue of Discrete Mathematics

Discrete Mathematics (journal)

Discrete Mathematics is a journal in the broad area of discrete mathematics, combinatorics, graph theory and their applications, published by Elsevier. It publishes both short notes, full length contributions, as well as survey articles. In addition, DM publishes a number of special issues each...

has been dedicated to the 150th birthday of Petersen, in which a very precise biography may be found.

External links