Almost Cohen-Macaulay algebras in mixed characteristic via Fontaine rings

Abstract

In the present paper, it is proved that any complete local domain of mixed characteristic has a weakly almost Cohen-Macaulay algebra in the sense that some system of parameters is a weakly almost regular sequence, which is a notion defined via a valuation. The central idea of this result originates from the main statement obtained by Heitmann to prove the Monomial Conjecture in dimension 3. In fact, A weakly almost Cohen-Macaulay algebra is constructed over the absolute integral closure of a complete local domain by applying the methods of Fontaine rings and Witt vectors. A connection of the main theorem with the Monomial Conjecture is also discussed.