The p-adic Simpson correspondence, recently initiated by Gerd Faltings,
aims at describing all p-adic representations of the fundamental group
of a proper smooth variety over a p-adic field in terms of linear
algebra-namely Higgs bundles. This book undertakes a systematic
development of the theory following two new approaches, one by Ahmed
Abbes and Michel Gros, the other by Takeshi Tsuji. The authors mainly
focus on generalized representations of the fundamental group that are
p-adically close to the trivial representation.The first approach relies
on a new family of period rings built from the torsor of deformations of
the variety over a universal p-adic thickening defined by J. M.
Fontaine. The second approach introduces a crystalline-type topos and
replaces the notion of Higgs bundles with that of Higgs isocrystals. The
authors show the compatibility of the two constructions and the
compatibility of the correspondence with the natural cohomologies. The
last part of the volume
contains results of wider interest in p-adic Hodge theory. The reader
will find a concise introduction to Faltings' theory of almost étale
extensions and a chapter devoted to the Faltings topos. Though this
topos is the general framework for Faltings' approach in p-adic Hodge
theory, it remains relatively unexplored. The authors present a new
approach based on a generalization of P. Deligne's covanishing topos.