A recurrent formula of $A_{\infty }$-quasi inverses of dg-natural transformations between dg-lifts of derived functors

Abstract

A dg-natural transformation between dg-functors is called an objectwise homotopy equivalence if its induced morphism on each object admits a homotopy inverse. In general an objectwise homotopy equivalence does not have a dg-inverse but has an $A_{\infty }$ quasi-inverse. In this note we give a recurrent formula of the $A_{\infty }$ quasi-inverse. This result is useful in studying the compositions of dg-lifts of derived functors of schemes.

10 pages, minor change