Summary
By considering Hamiltonian actions of real Lie groupsG (respectively real Lie algebrasg and complex Lie algebrasg o) not necessarily semi-simple on a real sympletic manifold, the suitable liftings into the Lie algebra of complex-valued functions defined on the manifold are examined. The analysis is centred on complex Cartan subalgebrash o⊂g o and the corresponding vector subspacese c spanned by the common eigenvectors arising from the restricted adjoint action on the root spaces ofg o. Some new insight about the structure of these algebras are obtained, which lead to the following main result:any (essential) action is Poissonian (i.e. the corresponding cohomology classes are null) on h o×e o.
Riassunto
Considerando azioni hamiltoniane di grupi di Lie realiG (rispettivamente algebre di Lie realig e algebre di Lie complesseg o) non necessariamente semisemplici su una varietà reale simplettica, si esaminano sollevamenti adeguati all’interno dell’algebra di Lie di funzioni e valori complessi sulla varietà. L’analisi è centrata su subalgebre complesse di Cartanh o⊂g o ed i corrispondenti sottospazi vettorialie o estesi dagli autovettori comuni che derivano dall’azione aggiunta ristretta sugli spazi originali dig o. Si ottengono alcufile nuove osservazioni riguardo la struttura di queste algebre, che portano al seguente importante risultato:qualsiasi azione (essenziale) è poissoniana (cioè le corrispondenti classi di coomologia sono nulle) su J o×e o.
Резюме
Рассматривая гамильтоновы действия для вещественных групп ЛиG (соответственно, вещественные алгебры Лиg, комплексные алгебры Лиg o), не обязательно полупростые на вещественном симплексном множестве, исследуются соответствующие поднимания в алгебре Ли комплексных функций, определенных на множестве. Проводится анализ комплексных субалгебр Картанаh o⊂g o и соответствующих векторных подпространствe o, сканируемых обшими собственными векторами, возникаюцими из ограниченного сопряженного действия на пространствахg o. Получаются некоторые новые представления, касаюшиеся этих алгебр, которые приводят к следующему основному реультату: любое (существенное) действие является пуассоновым (т.е. соответствующие когомологические классы являются нулевыми) наh o×e o.
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A complex tensor field is a section of the suitable complexified tensor bundle (over a real manifold) constructed, in a canonical way, through theC ∞ differentiable function ⊗C. A (real or complex) Lie algebra action on (M, w⊗lc) is a Lie-algebra homomorphism:. ClearlyG (respectivelyg) actions on (M, w ⊗ 1c) and (M, w) can be naturally identified (6).
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Bunchaft, F. Some determinations on the lifting problem of Hamiltonian actions on sympletic manifolds. Nuov Cim B 85, 149–160 (1985). https://doi.org/10.1007/BF02721556
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DOI: https://doi.org/10.1007/BF02721556