Theory of weights for log convergent cohomologies I: the case of a proper smooth scheme with an SNCD in characteristic p>0
Yukiyoshi Nakkajima, Atsushi Shiho
TL;DR
The paper develops a comprehensive log convergent cohomology framework for a proper smooth scheme with a relative SNCD in characteristic $p>0$, defining filtered complexes $(E_{ m conv},P)$ and $(C_{ m conv},P)$ within the log convergent topos. It proves a $p$-adic purity result for the weight-filtered convergent complex and shows a canonical isomorphism between $(E_{ m conv},P)$ and $(C_{ m conv},P)$, from which a weight spectral sequence for the log convergent cohomology arises. The authors establish functoriality and base-change properties, construct a weight-filtered theory with a Gysin boundary mechanism, and prove comparison theorems with zariskian and isozariskian frameworks, linking convergent, crystalline, and zariskian viewpoints. These results extend weight filtration and purity phenomena to log-convergent cohomology in positive characteristic, enabling refined structural and functorial analyses, including truncated and simplicial settings.
Abstract
Using log convergent topoi, %In the derived category of filtered complexes of %sheaves of modules over %an isostructure we define two fundamental filtered complexes $(E_{conv},P)$ and $(C_{conv},P)$ for the log scheme obtained by a smooth scheme with a relative simple normal crossing divisor over a scheme of characteristic $p>0$. Using $(C_{conv},P)$, we prove the $p$-adic purity. As a corollary of it, we prove that $(E_{conv},P)$ and $(C_{conv},P)$ are canonically isomorphic. These filtered complexes produce the weight spectral sequence of the log convergent cohomology sheaf of the log scheme. We also give the comparison theorem between the projections of $(E_{conv},P)$ and $(C_{conv},P)$ to the derived category of bounded below filtered complexes of sheaves of modules in the Zariski topos of the log scheme and the weight-filtered isozariskian filtered complex $(E_{zar},P)_{Q}$ of the log scheme defined in our previous book.
