Löwenheim-Skolem theorem

Meaning

Proper Noun

• A theorem stating that, if a countable first-order theory has an infinite model, then for every infinite cardinal number κ it has a model of size κ. The result implies that first-order theories are unable to control the cardinality of their infinite models, and that no first-order theory with an infinite model can have a unique model up to isomorphism.

Origin

• Named for Leopold Löwenheim and Thoralf Skolem.