### Cup-product for Leibniz cohomology, by Jean-Louis Loday

A Leibniz algebra is a vector space equipped with a bracket satisfying
[x,[y,z]] = [[x,y],z] - [[x,z],y]. A Lie algebra is an example of a Leibniz
algebra. A dual Leibniz algebra is a vector space equipped with a product
satisfying ((ab)c) = (a(bc)) + (a(cb)). Dual is taken in the operad sense,
so the tensor product of a Leibniz algebra by a dual Leibniz algebra is a
Lie algebra. In this paper it is proved that the Leibniz cohomology
HL^*(g) of the Leibniz algebra g is equipped with a cup-product which makes
it into a graded dual Leibniz algebra.

Jean-Louis Loday <loday@math.u-strasbg.fr>