Extension theorem
# Extension theorem

Extension theorem may refer to:

* Carathéodory's extension theorem - a theorem in measure theory, named after the Greek mathematician Constantin Carathéodory
* Dugundji extension theorem - a theorem in topology, named after the American mathematician James Dugundji
* Extension Lemma - a lemma in topology (resp. functional analysis), related to the Tietze extension theorem
* Hartogs' extension theorem - a theorem in the theory of functions of several complex variables
* Isomorphism extension theorem - a theorem in field theory
* Kolmogorov extension theorem - a theorem in probability theory, named after the Soviet mathematician Andrey Nikolaevich Kolmogorov
* Krein extension theorem - a theorem in functional analysis, proved by the Soviet mathematician Mark Grigorievich Krein
* M. Riesz extension theorem - a theorem in mathematics, proved by Marcel Riesz
* Szpilrajn extension theorem - a theorem in set theory, proved by Edward Szpilrajn
* Tietze extension theorem - a theorem in topology, named after the Austrian mathematician Heinrich Franz Friedrich Tietze
* Urysohn extension theorem - a theorem in topology, named after the mathematician Pavel Samuilovich Urysohn
* Whitney extension theorem - a theorem in mathematical analysis, named after the American mathematician Hassler Whitney
* Kreps extension theorem - a theorem in financial mathematics, ensuring that incomplete markets can be completed by adding the right securities
