Géza Fodor (mathematician)

Géza Fodor (born in Kocs, Hungary, in 1927, died in 1977) was a Hungarian mathematician known for his work in set theory, particularly in combinatorial set theory and large cardinals.

Fodor received his doctorate from the University of Szeged in 1952. He spent much of his career at the József Attila University in Szeged.

His most notable contribution is Fodor's Lemma, also known as the Pressing Down Lemma. This lemma is a fundamental result in set theory, specifically in the study of stationary sets and regressive functions on ordinals. It states that if S is a stationary subset of a regular uncountable cardinal κ, and f is a regressive function on S (i.e., f(α) < α for all α ∈ S, α ≠ 0), then there exists a stationary subset S' of S such that f is constant on S'.

Fodor's Lemma is a powerful tool used to prove other theorems in set theory, and it has applications in various areas, including the study of forcing, cardinal arithmetic, and the structure of the set-theoretic universe.

Besides Fodor's Lemma, Fodor also contributed to other areas of set theory, including research on cardinal numbers and infinitary combinatorics. His work has had a lasting impact on the field and continues to be relevant to current research.