Takehiko Gappo

About me

I am a mathematician working in set theory. In particular, I am interested in large cardinals, determinacy axioms, and inner model theory.

I am a postdoctoral researcher at TU Wien (Vienna, Austria) belonging to the Set Theory Group (FB8) of the Institute for Discrete Mathematics and Geometry. I am a member of the Inner Model Theory Workgroup. Since August 2025, I have been the principal investigator of FWF ESPRIT project Long Games and Strengthenings of Determinacy.

I received my bachelor's degree from the University of Tokyo (Japan) in March 2018, where I learned the basics of inner model theory from Daisuke Ikegami. I completed my PhD at Rutgers University (New Jersey, US) in October 2022 under the supervision of Grigor Sargsyan. Since November 2022 until July 2025, I was a project assistant of FWF projects V844 and I6087 led by Sandra Müller.

Upcoming schedule

May 31--June 12: Attending Inner Model Theory Conference in Będlewo and Warsaw to give an invited talk in the second week.

Past activities

In 2026:

June 5--7: Attending 4th Łódź Logic Conference at Łódź University of Technology.
May 18--22: I attended The 10th European Set Theory Conference in Helsinki to give a contributed talk.
April 7--16: I visited IMPAN in Warsaw to give lectures on HOD analysis.
March 23 & 24: I attended MSJ Spring Meeting 2026 at Tokyo University of Science, Japan.
March 9--13: I visited Shimonoseki (Japan) for research collaboration with Kenta Tsukuura.
February 16 & 17: Visiting Gdańsk to give a seminar talk at the weakly math seminar at the University of Gdańsk.
January 31--February 7: I attended Winter School in Abstract Analysis 2026 section Set Theory & Topology in Hejnice to give a contributed talk.

In 2025:

December 1--5: I visited Wrocław to give an invited seminar talk at Wrocław Set Theory & Topology Seminar.
November 7: My poster (joint with Tatsuya Goto) about research collaboration between TU Wien and Kobe University in set theory was presented by Goto in Japan Science Day 2025 at TU Wien.
November 3--7: I gave an invited talk at XVIII International Workshop in Set Theory in Luminy.
September 8--12: I attended Young Set Theory Workshop 2025 at TU Wien as one of the local organizers.
September 4--5: I gave a contributed talk at Logic Session and organized Minisymposium in Set Theory with Corey B. Switzer (University of Vienna) at ÖMG-DMV Annual Meeting 2025 in Linz.
July 8: I gave a contributed talk at Logic Colloquium 2025 at TU Wien.
June 23 -- July 4: I gave an invited talk at the 3rd Berkeley Conference on Inner Model Theory at UC Berkeley.
June 2--5: I visited Wrocław to give an invited seminar talk at Wrocław Set Theory & Topology Seminar.
May 9--11: I gave a poster presentation at the Roaming Logic Conference in Warsaw.
February 16--22: I gave an invited talk at the 7th Arctic Set Theory Workshop in Kilpisjärvi, Finland.
January 7--10: I visited Gdańsk for research collaboration with Grigor Sargsyan.

In 2024:

November 17--20: I visited Wrocław to give an invited seminar talk at Wrocław Set Theory & Topology Seminar.
October 10: I gave a contributed online talk at RIMS set theory conference (Kyoto/online). I talked about joint work with J. P. Aguilera on the equivalence between mice and determinacy of fixed countable length. My slides are available on their website.
October 8: I gave an invited talk at PhD Colloquium, which is part of Colloquium Logicum 2024 in Vienna. Invitation to speak at the PhD Colloquium is recognition of doctoral excellence within or connected to the German-speaking research community.

Contact Information

Takehiko Gappo, PhD (he/him)
takehiko.gappo [at] tuwien [dot] ac [dot] at

Institut für Diskrete Mathematik und Geometrie, TU Wien
Wiedner Hauptstraße 8-10/104, 1040 Wien, Austria.

March 22, 2026 in Kamakura.