| Gaisi Takeuti | |
| Native Name: | 竹内 外史 |
| Native Name Lang: | ja |
| Birth Date: | 25 January 1926 |
| Nationality: | Japanese |
| Fields: | Mathematics |
| Workplaces: | University of Illinois at Urbana–Champaign |
| Education: | Tokyo University |
| Alma Mater: | Princeton |
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| Thesis1 Year: | and |
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| Known For: | Work in proof theory |
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was a Japanese mathematician, known for his work in proof theory.[1]
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.[2] He is also known for his work on ordinal diagrams with Akiko Kino.