Publications & Preprints

• Research partially supported by the Knut & Alice Wallenberg Foundation and the Swedish Research Council

Preprints:

• (with S. Cooper) Hodge-Chern classes and strata-effectivity in tautological rings   

arXiv:2404.05727

• (with S. Reppen) An Ogus Principle for Zip period maps: The Hasse invariant's vanishing order via `Frobenius and the Hodge filtration'

arXiv:2404.05707 

• (with J.-S. Koskivirta) Griffiths-Schmid conditions for automorphic forms via characteristic p

arXiv:2211.16819 

• (with J.-S. Koskivirta) Divisibility of mod p automorphic forms and the cone conjecture for certain Shimura varieties of Hodge-type

arXiv:2211.16817 

• Classification of Hasse-type zip data, Appendix to Weights of mod p automorphic forms and partial Hasse invariants by N. Imai & J.-S. Koskivirta

arXiv:2211.16207 

Publications:

12. Quasi-constant fundamental weights in terms of Levi subgroups

J. Algebra., 559 (2020), pp. 87-94     

levi_weyl.pdf 

11. The Griffiths bundle is generated by groups 

Math. Ann. 375 (2019), pp. 1283-1305     

 griffiths_bundle.pdf Open Access 

10. (with Jean-Stefan Koskivirta) Strata Hasse invariants, Hecke algebras and Galois representations  

Invent. Math. 217 No. 3 (2019), pp. 887--984.   

strata_hasse.pdf Open Access

9. (with Jean-Stefan Koskivirta) Quasi-constant characters: Motivation, classification and applications. 

Adv. in Math. 339 (2018), pp. 336--366

quasi_constant.pdf 

8. (with Jean-Stefan Koskivirta) Automorphic vector bundles with global sections on G-Zip^Z-schemes. 

Compositio Math., 154 (2018), pp. 2586--2605

global_sections.pdf 

7.  (with Jean-Stefan Koskivirta) Stratification of flag spaces and functoriality. 

IMRN No. 12 (2019), pp. 3646-3682                                                           

 zip_flags.pdf 

6. (with Marc-Hubert Nicole) The $\mu$-ordinary Hasse invariant of unitary Shimura varieties. 

J. reine angew. Math. 728 (2017), pp. 137–151. 

 mu_hasse.pdf 

Notes: Merges our two previous preprints,  "A \mu-ordinary Hasse invariant" (arXiv:1302.1614v2) and "The \mu-ordinary Hasse invariant of unitary Shimura varieties" (arXiv:1305.6956v1). 

5. An introduction to the Langlands correspondence. 

pp. 333-367  of "Recent Advances in Hodge Theory: Period Domains, Algebraic Cycles, and Arithmetic". Proceedings of a conference held at the Pacific Institute for the Mathematical Sciences, Vancouver, Canada in June 2013. Matt Kerr and Gregory Pearlstein editors, Cambridge University Press, 2016.  

intro_vancouver.pdf 

Notes: Based on three expository lectures given at the above conference.

4.  (With an appendix by Sug Woo Shin) Galois Representations Associated to Holomorphic Limits of Discrete Series. 

Compositio Math. 150  (2014) pp.191-228

galois_hlds.pdf 

3. A new proof of Belyi's Theorem. 

J. Number Theory 135 (2014) pp. 151-154

  belyi_new_proof 

2. Unifying Themes Suggested by Belyi's Theorem. 

pp. 181--214 of Number Theory, Analysis and Geometry (Serge Lang Memorial Volume). D. Goldfeld, J. Jorgenson, P. Jones, D. Ramakrishnan, K. Ribet, J. Tate eds. Springer-Verlag, 2011

unifying_belyi.pdf 

1. Dynamics of the w function and primes. 

J. Number Theory 119 (2006) pp. 86-98

w_function.pdf