Algebraic Geometry Seminar

Organizers：

Caucher Birkar，贾甲

Speaker：

Hsueh-Yung Lin 林学庸 (台湾大学)

Time：

Fri., 15:30-16:30, Nov. 7, 2025

Online：

Zoom Meeting ID: 262 865 5007

Passcode: YMSC

Venue:

B725, Shuangqing Complex Building A

Title:

On the unboundedness of birational automorphisms

Abstract:

We formulate boundedness questions for birational automorphisms and discuss to which extent the Cremona groups exhibit unbounded behavior. As an example, we show that over a field of characteristic zero, the weak factorization centers occurring in the Cremona transformations of P^N do not belong to a birationally bounded family whenever N ≥ 4, even after cancellations up to birational equivalence of their MRC bases. (Based on joint work with Evgeny Shinder.)