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Aug 11, 2021 at 14:53 comment added Lightmann Thank @RobertBryant. Are there some references or books on this topic?
Aug 10, 2021 at 15:23 answer added Robert Bryant timeline score: 4
Aug 10, 2021 at 12:16 comment added Robert Bryant The Laplacian of $H$ with respect to the induced metric is 4-th order invariant of the surface, while $H$ and $K$ are only 2-nd order invariants. It's easy to show that there cannot be any generally valid formula of the form $\Delta_SH = F(H,K)$, though, of course, there are plenty of examples of local surfaces that satisfy this equation for a given function $F$.
Aug 10, 2021 at 0:21 comment added Lightmann Thanks Ben McKay and Deane Yang. My aim is to approximate $\Delta_S H$ by some polynomials of $H, K$. I don't know how to derive it. Is there some reference on this direction? Why the result is not a function of $H,K$? @BenMcKay
Aug 9, 2021 at 19:00 comment added Deane Yang A reasonable analogy of your question would be the following: Suppose $f$ and $g$ are scalar functions (on $\mathbb{R}^2$ for simplicity) such that $\Delta f = g$. What's the formula for $\Delta g$? There's not much you can say beyond the fact that $\Delta g = \Delta^2f$. The answer here would be similar.
Aug 9, 2021 at 16:49 comment added Ben McKay What sort of quantities do you allow in the dots? Obviously not the Laplace Beltrami of $H$, so maybe not derivatives. Perhaps polynomials in $H,K$? Clearly it is not a function of $H,K$.
Aug 9, 2021 at 16:36 review First posts
Aug 9, 2021 at 16:53
Aug 9, 2021 at 16:31 history asked Lightmann CC BY-SA 4.0