Bochner identity: Difference between revisions

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	In ] — specifically, ] — the '''Bochner identity''' is an ] concerning ]s between ]s. The identity is named after the ] ] ].		In ] — specifically, ] — the '''Bochner identity''' is an ] concerning ]s between ]s. The identity is named after the ] ] ].

Revision as of 17:54, 25 February 2012

In mathematics — specifically, differential geometry — the Bochner identity is an identity concerning harmonic maps between Riemannian manifolds. The identity is named after the American mathematician Salomon Bochner.

Let M and N be Riemannian manifolds and let u : M → N be a harmonic map. Let d denote the exterior derivative, ∇ the gradient, Δ the Laplace–Beltrami operator, Riem_N the Riemann curvature tensor on N and Ric_M the Ricci curvature tensor on M. Then

\Delta {\big (}|\nabla u|^{2}{\big )}={\big |}\nabla (\mathrm {d} u){\big |}^{2}+{\big \langle }\mathrm {Ric} _{M}\nabla u,\nabla u{\big \rangle }-{\big \langle }\mathrm {Riem} _{N}(u)(\nabla u,\nabla u)\nabla u,\nabla u{\big \rangle }.

Eells, J (1978). "A report on harmonic maps". Bull. London Math. Soc. 10 (1): 1–68. doi:10.1112/blms/10.1.1. MR 0495450. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)