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Double Poisson brackets and involutive representation spaces

  • Grigori Olshanski,
  • Nikita Safonkin

摘要

Let \(\Bbbk \) k be an algebraically closed field of characteristic 0 and A be a finitely generated associative \(\Bbbk \) k -algebra, in general noncommutative. One assigns to A a sequence of commutative \(\Bbbk \) k -algebras \(\mathcal {O}(A,d)\) O ( A , d ) , \(d=1,2,3,\dots \) d = 1 , 2 , 3 , , where \(\mathcal {O}(A,d)\) O ( A , d ) is the coordinate ring of the space \({\text {Rep}}(A,d)\) Rep ( A , d ) of d-dimensional representations of the algebra A. A double Poisson bracket on A in the sense of Van den Bergh (Trans Am Math Soc 360:5711–5799, 2008) is a bilinear map \(\{\!\{-,-\}\!\}\) { { - , - } } from \(A\times A\) A × A to \(A^{\otimes 2}\) A 2 , subject to certain conditions. Van den Bergh showed that any such bracket \(\{\!\{-,-\}\!\}\) { { - , - } } induces Poisson structures on all algebras \(\mathcal {O}(A,d)\) O ( A , d ) . We propose an analog of Van den Bergh’s construction, which produces Poisson structures on the coordinate rings of certain subspaces of the representation spaces \({\text {Rep}}(A,d)\) Rep ( A , d ) . We call these subspaces the involutive representation spaces. They arise by imposing an additional symmetry condition on \({\text {Rep}}(A,d)\) Rep ( A , d ) —just as the classical groups from the series B, C, D are obtained from the general linear groups (series A) as fixed point sets of involutive automorphisms.