Gaisi Takeuti

Gaisi Takeuti
竹内 外史
Born(1926-01-25)January 25, 1926
DiedMay 10, 2017(2017-05-10) (aged 91)
NationalityJapanese
EducationTokyo University
Alma materPrinceton
Known forWork in proof theory
Scientific career
FieldsMathematics
InstitutionsUniversity of Illinois at Urbana–Champaign

Gaisi Takeuti (竹内 外史, Takeuchi, Gaishi; January 25, 1926 – May 10, 2017) was a Japanese mathematician, known for his work in proof theory.

After graduating from Tokyo University, he went to Princeton to study under Kurt Gödel. He later became a professor at the University of Illinois at Urbana–Champaign. Takeuti was president (2003–2009) of the Kurt Gödel Society, having worked on the book Memoirs of a Proof Theorist: Godel and Other Logicians. His goal was to prove the consistency of the real numbers. To this end, Takeuti's conjecture speculates that a sequent formalisation of second-order logic has cut-elimination. He is also known for his work on ordinal diagrams with Akiko Kino.