English

Duality for higher local fields after Kato and Suzuki

Number Theory 2026-03-16 v2

Abstract

A field KK is dd-local if there exist fields K=kd,...,k0K=k_d,...,k_0 with ki+1k_{i+1} complete discrete valuation with residue field kik_i, and k0k_0 finite of characteristic pp. By work of Deninger and Wingberg, the Galois cohomology of such fields with finite coefficients satisfies a duality generalizing Tate duality when either d=0d=0, chark1=0\mathrm{char} k_1=0 or the coefficients have no pp-torsion. Reviewing and synthesizing results of Suzuki and Kato, we obtain pp-torsion duality statements under the weaker assumption that either d1d\leq 1 or chark2=0\mathrm{char} k_2=0, as well as for varieties over KK, where duality is stated in terms of locally compact Hausdorff topologies on the \'etale cohomology groups. More generally we obtain results for any perfect k0k_0, endowing the totally unramified cohomology groups of KK with the structure of ind-pro-quasi-algebraic k0k_0-groups.

Keywords

Cite

@article{arxiv.2512.00886,
  title  = {Duality for higher local fields after Kato and Suzuki},
  author = {Antoine Galet},
  journal= {arXiv preprint arXiv:2512.00886},
  year   = {2026}
}

Comments

73 pages. Main results and general structure of the paper are unchanged. Added detail to several proofs, some as separate lemmas, corrected typos. Reworked arguments in section 1.6, removed mistaken (but unused) statement in section 1.1. Comments are welcome !

R2 v1 2026-07-01T08:01:47.642Z