This morning, Michel Van den Bergh posted an interesting paper on the arXiv entitled Double Poisson Algebras. His main motivation was the construction of a natural Poisson structure on quotient varieties of representations of deformed multiplicative preprojective algebras (introduced by Crawley-Boevey and Shaw in Multiplicative preprojective algebras, middle convolution and the Deligne-Simpson problem) which he achieves by extending his double Poisson structure on the path algebra of the quiver to the 'obvious' universal localization, that is the one by inverting all 1+aa^{\star} for a an arrow and a^{\star} its double (the one in the other direction).
For me the more interesting fact of this paper is that his double bracket on the path algebra of a double quiver gives finer information than the necklace Lie algebra as defined in my (old) paper with Raf Bocklandt Necklace Lie algebras and noncommutative symplectic geometry. I will certainly come back to this later when I have more energy but just to wet your appetite let me point out that Michel calls a double bracket on an algebra A a bilinear map
\{ \{ -,- \} \}~:~A \times A
\rightarrow A \otimes A
which is a derivation in the second argument (for the outer bimodulke structure on A) and satisfies
\{ \{ a,b \} \} = – \{ \{ b,a \} \}^o with ~(u \otimes v)^0 = v
\otimes u
Given such a double bracket one can define an ordinary bracket (using standard Hopf-algebra notation)
\{ a,b \} = \sum
\{ \{ a,b \} \}_{(1)} \{ \{ a,b \} \}_{(2)}
which makes A into a Loday algebra and induces a Lie algebra structure on A/[A,A]. He then goes on to define such a double bracket on the path algebra of a double quiver in such a way that the associated Lie structure above is the necklace Lie algebra.

Previous in series

Next in series

arxiv, geometry, necklace, noncommutative, representations