Laplace-Beltrami Operator

A self-adjoint elliptic differential operator defined somewhat technically as

$$\Delta=d\delta+\delta d,$$

where $d$ is the Exterior Derivative and $d$ and $\delta$ are adjoint to each other with respect to the Inner Product.

References

Iyanaga, S. and Kawada, Y. (Eds.). Encyclopedic Dictionary of Mathematics. Cambridge, MA: MIT Press, p. 628, 1980.