SIYAN DANIEL LI-HUERTA


Picture of me in Brussels.

Department of Mathematics

Harvard University

sli@math.harvard.edu

I am a fifth-year graduate student at Harvard University advised by Mark Kisin.

For a year, I was a graduate student at the University of Chicago. Before that, I was an undergraduate at Princeton University, where my senior thesis was advised by Sophie Morel.

I currently co-organize the Harvard Number Theory Seminar.

RESEARCH

Local-global compatibility over function fields. (pdf) (arXiv)

We prove that V. Lafforgue's global Langlands correspondence is compatible with Fargues–Scholze's semisimplified local Langlands correspondence. As a consequence, we canonically lift Fargues–Scholze's construction to a non-semisimplified local Langlands correspondence for local fields of characteristic p ≥ 5. We also deduce that Fargues–Scholze's construction agrees with that of Genestier–Lafforgue, answering a question of Fargues–Scholze, Hansen, Harris, and Kaletha. The proof relies on a uniformization morphism for moduli spaces of shtukas.

The plectic conjecture over local fields. (pdf) (arXiv)

Using a mixed-characteristic incarnation of fusion, we prove an analog of Nekovář–Scholl's plectic conjecture for local Shimura varieties. We apply this to obtain results on the plectic conjecture for (global) Shimura varieties after restricting to a decomposition group. Along the way, we prove a p-adic uniformization theorem for the basic locus of abelian type Shimura varieties at hyperspecial level, which is of independent interest.

The plectic conjecture over function fields. (pdf) (arXiv)

We prove the plectic conjecture of Nekovář–Scholl over global function fields Q. For example, when the cocharacter is defined over Q and the structure group is a Weil restriction from a geometric degree d separable extension F/Q, consider the complex computing ℓ-adic intersection cohomology with compact support of the associated moduli space of shtukas over QI. We endow this with the structure of a complex of (Weil(F)d rtimes Sd)I-modules, which extends its structure as a complex of Weil(Q)I-modules constructed by Arinkin–Gaitsgory–Kazhdan–Raskin–Rozenblyum–Varshavsky. We show that the action of (Weil(F)d rtimes Sd)I commutes with the Hecke action, and we give a moduli-theoretic description of the action of Frobenius elements in Weil(F)d×I.

The local Langlands correspondence for GLn over function fields. (pdf) (arXiv) (ANT)

Let F be a local field of characteristic p > 0. By adapting methods of Scholze, we give a new proof of the local Langlands correspondence for GLn over F. More specifically, we construct ℓ-adic Galois representations associated with many discrete automorphic representations over global function fields, which we use to construct a map π→rec(π) from isomorphism classes of irreducible smooth representations of GLn(F) to isomorphism classes of n-dimensional semisimple continuous representations of WF. Our map rec is characterized in terms of a local compatibility condition on traces of a certain test function fτ,h, and we prove that rec equals the usual local Langlands correspondence (after forgetting the monodromy operator).