Definition 0.1
Let
be a quasi-bialgebra
with reassociator
. A left
-module
together with a left
-coaction
,
is called a left Yetter-Drinfeldmodule
if the following equalities hold, for all
and
:
and
and
Remark
This module (ref.[1]) is essential for solving the quasi-Yang-Baxter equation which is an important relation in mathematical physics.
Let us consider a module that operates over a ring of functions on a curve over a finite field, which is called an elliptic module. Such modules were first studied by Vladimir Drinfel'd in 1973 and called accordingly Drinfel'd modules.