Wavy Lie algebra and its Koszul dual
1 Wavy Lie algebra
Let be a Lie group. It is possible to introduce the structure of a Lie group on .
In fact:
and the structure of the group is introduced by pointwise multiplication. Consider the corresponding Lie superalgebra:
We can interpret as the algebra of maps from to ;
therefore the elements of are -valued functions of an odd
parameter .
It is possible to extend by an extra odd element with the following
commutation relations:
We will call this extended algebra .
2 Koszul dual to wavy Lie algebra
Let us consider the universal enveloping and look at it as a quadratic-linear
algebra. The dual algebra is a differential algebra; it has a nonzero differential because the
original algebra was quadratic-linear; the differential corresponds to the commutator.
We will call it :
This is generated by the linear space: .
Let be the basis of as a linear space.
Then is generated
by odd elements and even elements :
As a dual to a non-homogeneous quadratic-linear algebra,
the supercommutative algebra comes with the differential:
But since was actually a DLA, the differential being ,
the dual map defines the second differential on :
These two differentials commute:
The total differential is called :
Schematically:
Notice that:
The cohomology of is ; this can be proven using the homotopy operator: