1878 – 1957
Leopold Löwenheim (1878-1957) was a German mathematician and logician best known for his foundational contributions to mathematical logic and model theory. His 1915 paper 'Über Möglichkeiten im Relativkalkül' established what became the Löwenheim-Skolem theorem, a cornerstone result concerning the cardinality of models of first-order theories.
Proved the original form of the Löwenheim-Skolem theorem (1915)
Established foundational results in the relative calculus and quantification theory
Contributed to the early development of model theory
Advanced Schröder's algebra of logic tradition
Demonstrated decidability of monadic first-order logic