This seminar is jointly organized by Bjoern Bringmann (at Caltech) and Sehyun Ji, Stepan Malkov, and Terence Tao (at UCLA). It is held roughly every other week, typically on Fridays from 3-5 pm (Pacific time). Its physical location alternates between Caltech (Linde 310) and UCLA (MS 6627).
Fall 2026
October 9th (at Caltech, note the unusual time):
2-3 pm: Sung-Jin Oh (UC Berkeley)
Title: An h-principle for general relativistic initial data sets.
Abstract: I will discuss a new flexibility result for the Einstein constraint equations, which may be interpreted as an analogue of the Nash-Kuiper theory for isometric embeddings. As an application, we generalize smooth obstruction-free gluing theorems of Czimek-Rodnianski (later sharpened by Mao-Oh-Tao). This is joint work with Jonathan Luk, Yuchen Mao, and Zhongkai Tao.
3-4 pm: Kevin Ren (Princeton)
Title: Bounding the Euclidean Distortion of Negative-Type Metric Spaces, revisited.
Abstract: We show that any N-point negative-type metric space admits a bi-Lipschitz embedding into Euclidean space with distortion O(sqrt(log N)), which is sharp up to constant factors. This was previously done in joint work with Assaf Naor and Alan Chang via a refinement of the chaining argument of Arora-Rao-Vazirani. In this talk, we present an alternative metric-based argument with surprising connections to Ball's extension theorem and Markov type. Joint work with Assaf Naor.
October 23rd (at UCLA):
3-4 pm: Will Feldman (University of Utah)
Title: TBD
4-5 pm: Lars Becker (Princeton University)
Title: TBD
November 13th (at Caltech):
3-4 pm: Paata Ivanisvili (UC Irvine)
Title: TBD
4-5 pm: Ben Pineau (NYU)
Title: TBD
November 20th (at UCLA):
3-4 pm: Wilhelm Schlag (Yale)
Title: TBD
4-5 pm: Jason Zhao (UC Berkeley)
Title: TBD