# nLab twisted module of homomorphisms

Let $C$ be a dg-coalgebra, $A$ a dg-algebra, $N$ a left $C$-dg-comodule with coaction $\delta_N:N\to C\otimes N$, $P$ a left $A$-dg-module with action $m_P:A\otimes P\to P$ and $\tau:C\to A$ a twisting cochain. The twisted module of homomorphisms $\mathrm{Hom}_\tau(N,P)$ is a chain complex which as a graded module coincides with the ordinary module of homomorphisms of the underlying chain complex $\mathrm{Hom}(N,P)$, and with the differential $d_\tau$ given by

$d_\tau(f) = d(f) + m_P\circ(\tau\otimes f)\circ\delta_N,$

where $f\in\mathrm{Hom}(N,P)$.

Revised on March 15, 2009 22:32:33 by Zoran Škoda (195.37.209.180)