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In differential geometry, the Kirwan map, introduced by British mathematician Frances Kirwan, is the homomorphism : where *''M'' is a Hamiltonian G-space; i.e., a symplectic manifold acted by a Lie group ''G'' with a moment map . * is the equivariant cohomology ring of ''M''; i.e.. the cohomology ring of the homotopy quotient of ''M'' by ''G''. * is the symplectic quotient of ''M'' by ''G'' at a regular central value of . It is defined as the map of equivariant cohomology induced by the inclusion followed by the canonical isomorphism . A theorem of Kirwan says that if ''M'' is compact, then the map is surjective in rational coefficients. The analogous result holds between the K-theory of the symplectic quotient and the equivariant topological K-theory of ''M''.〔M. Harada, G. Landweber. Surjectivity for Hamiltonian G-spaces in K-theory. Trans. Amer. Math. Soc. 359 (2007), 6001--6025.〕 == References == 〔 *F. C. Kirwan, Cohomology of Quotients in Complex and Algebraic Geometry, Mathematical Notes 31, Princeton University Press, Princeton N. J., 1984. 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Kirwan map」の詳細全文を読む スポンサード リンク
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