In mathematics, a quasi-Frobenius Lie algebra
![(\mathfrak{g},[\,\,\,,\,\,\,],\beta )](http://wpcontent.answcdn.com/wikipedia/en/math/e/6/7/e6778bc97f09d2f373e33027c0e6642b.png)
over a field k is a Lie algebra
![(\mathfrak{g},[\,\,\,,\,\,\,] )](http://wpcontent.answcdn.com/wikipedia/en/math/7/a/2/7a202d338024a90e91c3f5b17bfb4cf0.png)
equipped with a nondegenerate skew-symmetric bilinear form
, which is a Lie algebra 2-cocycle of
with values in k. In other words,![\beta \left(\left[X,Y\right],Z\right)+\beta \left(\left[Z,X\right],Y\right)+\beta \left(\left[Y,Z\right],X\right)=0](http://wpcontent.answcdn.com/wikipedia/en/math/0/8/5/08571fc40803fb0b50e8e1d28f2fab8d.png)
for all X, Y, Z in
.
If β is a coboundary, which means that there exists a linear form
such that
![\beta(X,Y)=f(\left[X,Y\right]),](http://wpcontent.answcdn.com/wikipedia/en/math/8/5/3/853223266d9610ce6c1042a3f28d6ed7.png)
then
![(\mathfrak{g},[\,\,\,,\,\,\,],\beta )](http://wpcontent.answcdn.com/wikipedia/en/math/e/6/7/e6778bc97f09d2f373e33027c0e6642b.png)
is called a Frobenius Lie algebra.
If
is a quasi-Frobenius Lie algebra, one can define on
another bilinear product
by the formula
.Then one has
and

is a pre-Lie algebra.
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