Gerhard Hessenberg was a German

Germany

Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 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....

. He received his Ph.D from the University of Berlin in 1899 under the guidance of Hermann Schwarz

Hermann Schwarz

Karl Hermann Amandus Schwarz was a German mathematician, known for his work in complex analysis. He was born in Hermsdorf, Silesia and died in Berlin...

 and Lazarus Fuchs

Lazarus Fuchs

Lazarus Immanuel Fuchs was a German mathematician who contributed important research in the field of linear differential equations...

. His name is usually associated with projective geometry

Projective geometry

In mathematics, projective geometry is the study of geometric properties that are invariant under projective transformations. This means that, compared to elementary geometry, projective geometry has a different setting, projective space, and a selective set of basic geometric concepts...

, where he is known for proving that Desargues' theorem

Desargues' theorem

In projective geometry, Desargues' theorem, named in honor of Gérard Desargues, states:Denote the three vertices of one triangle by a, b, and c, and those of the other by A, B, and C...

 is a consequence of Pascal's theorem

Pascal's theorem

In projective geometry, Pascal's theorem states that if an arbitrary hexagon is inscribed in any conic section, and pairs of opposite sides are extended until they meet, the three intersection points will lie on a straight line, the Pascal line of that configuration.- Related results :This theorem...

, and set theory

Set theory

Set theory is the branch of mathematics that studies sets, which are collections of objects. Although any type of object can be collected into a set, set theory is applied most often to objects that are relevant to mathematics...

 where he is known for introducing the concept of a connection

Connection (mathematics)

In geometry, the notion of a connection makes precise the idea of transporting data along a curve or family of curves in a parallel and consistent manner. There are a variety of kinds of connections in modern geometry, depending on what sort of data one wants to transport...

. The Hessenberg sum and product of ordinals are named for him. However, Hessenberg matrices

Hessenberg matrix

In linear algebra, a Hessenberg matrix is a special kind of square matrix, one that is "almost" triangular. To be exact, an upper Hessenberg matrix has zero entries below the first subdiagonal, and a lower Hessenberg matrix has zero entries above the first superdiagonal...

 are named for Karl Hessenberg

Karl Hessenberg

Karl Adolf Hessenberg was a German mathematician and engineer. The Hessenberg matrix form is named after him...

, a near relative.

External links

• Gerhard Hessenberg at the Mathematics Genealogy Project.