Tibor Gallai (born Tibor Grünwald, 15 July 1912 â 2 January 1992) was a Hungarian mathematician. He worked in combinatorics, especially in graph theory, and was a lifelong friend and collaborator of Paul Erdà Âs. He was a student of Dénes Kà Ânig and an advisor of László Lovász. He was a corresponding member of the Hungarian Academy of Sciences (1991).
The Edmonds–Gallai decomposition theorem, which was proved independently by Gallai and Jack Edmonds, describes finite graphs from the point of view of matchings. Gallai also proved, with Milgram, Dilworth's theorem in 1947, but as they hesitated to publish the result, Dilworth independently discovered and published it.
Gallai was the first to prove the higher-dimensional version of van der Waerden's theorem.
With Paul Erdà Âs he gave a necessary and sufficient condition for a sequence to be the degree sequence of a graph, known as the Erdà ÂsâÂÂGallai theorem.