László Rédei was a Hungarian 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....

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He graduated from the University of Budapest and initially worked as a schoolteacher. In 1940 he was appointed professor in the University of Szeged

University of Szeged

The University of Szeged is one of Hungary's most distinguished universities, and is among the most prominent higher education institutions in Central Europe...

 and in 1967 moved to the Mathematical Institute of the Hungarian Academy of Sciences

Hungarian Academy of Sciences

The Hungarian Academy of Sciences is the most important and prestigious learned society of Hungary. Its seat is at the bank of the Danube in Budapest.-History:...

 in Budapest

Budapest

Budapest is the capital of Hungary. As the largest city of Hungary, it is the country's principal political, cultural, commercial, industrial, and transportation centre. In 2011, Budapest had 1,733,685 inhabitants, down from its 1989 peak of 2,113,645 due to suburbanization. The Budapest Commuter...

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His mathematical work was in algebraic number theory

Algebraic number theory

Algebraic number theory is a major branch of number theory which studies algebraic structures related to algebraic integers. This is generally accomplished by considering a ring of algebraic integers O in an algebraic number field K/Q, and studying their algebraic properties such as factorization,...

 and abstract algebra

Abstract algebra

Abstract algebra is the subject area of mathematics that studies algebraic structures, such as groups, rings, fields, modules, vector spaces, and algebras...

, especially group theory

Group theory

In mathematics and abstract algebra, group theory studies the algebraic structures known as groups.The concept of a group is central to abstract algebra: other well-known algebraic structures, such as rings, fields, and vector spaces can all be seen as groups endowed with additional operations and...

. He proved that every finite tournament

Tournament

A tournament is a competition involving a relatively large number of competitors, all participating in a sport or game. More specifically, the term may be used in either of two overlapping senses:...

 contains an odd number of Hamiltonian path

Hamiltonian path

In the mathematical field of graph theory, a Hamiltonian path is a path in an undirected graph that visits each vertex exactly once. A Hamiltonian cycle is a cycle in an undirected graph that visits each vertex exactly once and also returns to the starting vertex...

s. He gave several proofs of the theorem on quadratic reciprocity

Quadratic reciprocity

In number theory, the law of quadratic reciprocity is a theorem about modular arithmetic which gives conditions for the solvability of quadratic equations modulo prime numbers...

. He proved important results concerning the invariants of the class groups of quadratic number field

Quadratic field

In algebraic number theory, a quadratic field is an algebraic number field K of degree two over Q. It is easy to show that the map d ↦ Q is a bijection from the set of all square-free integers d ≠ 0, 1 to the set of all quadratic fields...

s. In several cases, he determined if the ring of integers of the real quadratic field Q(√d) is Euclidean or not. He successfully generalized Hajós's theorem. This led him to the investigations of lacunary polynomials over finite field

Finite field

In abstract algebra, a finite field or Galois field is a field that contains a finite number of elements. Finite fields are important in number theory, algebraic geometry, Galois theory, cryptography, and coding theory...

s, which he eventually published in a book. He introduced a very general notion of skew product of groups, both the Schreier-extension and the Zappa-Szép product

Zappa-Szep product

In mathematics, especially group theory, the Zappa–Szép product describes a way in which a group can be constructed from two subgroups. It is a generalization of the direct and semidirect products...

 are special case of. He explicitly determined those finite noncommutative groups whose all proper subgroups were commutative (1947). This is one of the very early results which eventually led to the classification of all finite simple groups.

He was the president of the János Bolyai Mathematical Society

János Bolyai Mathematical Society

The János Bolyai Mathematical Society is the Hungarian mathematical society, named after János Bolyai, a 19th century Hungarian mathematician, a co-discoverer of non-Euclidean geometry. It is the professional society of the Hungarian mathematicians, applied mathematicians, and mathematics teachers...

 (1947–1949). He was awarded the Kossuth Prize twice. He was elected corresponding member (1949), full member (1955) of the Hungarian Academy of Sciences

Hungarian Academy of Sciences

The Hungarian Academy of Sciences is the most important and prestigious learned society of Hungary. Its seat is at the bank of the Danube in Budapest.-History:...

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His books

• Ladislaus Rédei: Algebra. Erster Teil, Mathematik und ihre Anwendungen in Physik und Technik, Reihe A, 26, Teil 1 Akademische Verlagsgesellschaft, Geest & Portig, K.-G., Leipzig, 1959 xv+797 pp.
• Ladislaus Rédei: Theorie der endlich erzeugbaren kommutativen Halbgruppen, Hamburger Mathematische Einzelschriften, 41, Physica-Verlag, Würzburg 1963 228 pp.
• Ladislaus Rédei: Lückenhafte Polynome über endlichen Körpern, Lehrbücher und Monographien aus dem Gebiete der exakten Wissenschaften, Mathematische Reihe, 42, Birkhäuser Verlag, Basel-Stuttgart, 1970. 271 pp.
• L. Rédei: Endliche p-Gruppen, Akadémiai Kiadó, Budapest, 1989. 304 pp. ISBN 963-054660-4