Landau's constants

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In complex analysis, a branch of mathematics, Landau's constants( EdmundLandau   1929 ) are certain mathematical constants that describe the behaviour of holomorphic functions defined on the unit disk. Consider the set F of all those holomorphic functions f on the unit disk for which

Complex analysis Branch of mathematics studying functions of a complex variable

Complex analysis, traditionally known as the theory of functions of a complex variable, is the branch of mathematical analysis that investigates functions of complex numbers. It is useful in many branches of mathematics, including algebraic geometry, number theory, analytic combinatorics, applied mathematics; as well as in physics, including the branches of hydrodynamics, thermodynamics, and particularly quantum mechanics. By extension, use of complex analysis also has applications in engineering fields such as nuclear, aerospace, mechanical and electrical engineering.

Edmund Landau German Jewish mathematician

Edmund Georg Hermann Landau was a German mathematician who worked in the fields of number theory and complex analysis.

A mathematical constant is a number that is "significantly interesting in some way". Constants arise in many areas of mathematics, with constants such as e and π occurring in such diverse contexts as geometry, number theory, and calculus.

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We define Lf to be the radius of the largest disk contained in the image of f, and Bf to be the radius of the largest disk that is the biholomorphic image of a subset of a unit disk.

Landau's constants are then defined as the infimum of Lf or Bf, where f is any holomorphic function or any injective holomorphic function on the unit disk with

The three resulting constants are abbreviated L, B, and A (for injective functions), respectively.

The exact values of L, B, and A are not known, but it is known that

B is the Bloch's constant.

(sequence A081760 in the OEIS )

See also

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