📜 Theorem, law or theory

Carathéodory's measure extension theorem

Teorema de extensión de medidas de Carathéodory

Date
1914-1918 · confidence high
Place
Göttingen, Lower Saxony, Germany
Credited to
Constantin Carathéodory
Field
Knowledge & symbols

What was discovered

He introduced the outer measure and the measurability criterion that allow a measure defined on an algebra to be extended to a σ-algebra. It is the basis of Lebesgue measure and of measure in probability.

The criterion appeared in 1914 (Göttinger Nachrichten) and the theorem was spread by Vorlesungen über reelle Funktionen (1918). Carathéodory was born in Berlin to a Greek family from Constantinople.

What it led to

  • Kolmogorov's axiomatic probability
  • abstract integration

Links

Sources✓ verified 2026-11-04