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A surface is a generalization of a plane which needs not be flat, that is, the curvature is not necessarily zero. This is analogous to a curve generalizing a straight line
24
votes
Accepted
What is the analog of the "Fundamental Theorem of Space Curves," for surfaces, and beyond?
I've added a few sentences to my answer to clarify something that some readers may be wondering about, which is why there isn't as simple an answer for surfaces in $3$-space as there is for curves in …
19
votes
A necessary and sufficient condition for a space curve to lie on a ellipsoid
There is a straightforward way to deduce necessary conditions for a space curve to lie on an ellipsoid, and it's really a matter of calculation to make these conditions explicit in terms of the curvat …
18
votes
Accepted
How useful/pervasive are differential forms in surface theory?
Well, there's really not a whole lot more to say beyond what Deane already wrote. He certainly hit the main points, but maybe I can expand a bit on what he wrote and comment on my own experience over …
18
votes
Accepted
When does the shape operator commute with a derivative?
The question is essentially equivalent to the following classical question: Given a smooth surface $S$ and a bundle map $L:TS\to TS$, when does there exist an immersion $x:S\to \mathbb{R}^3$ such tha …
17
votes
Accepted
Geodesics on the twisted pseudosphere (Dini's surface)
To answer Joseph's questions:
First, it's not impossible to integrate the geodesic flow of the hyperbolic plane in these coordinates, but the formulae I got aren't very nice, so I'm not going to type …
17
votes
Accepted
Variation of curvature with respect to immersion?
If you just calculate using the moving frame, you'll get the answer for the variation of the principal curvatures in a few lines:
$$
\delta\kappa_i = \mathrm{Hess}(u)(e_i,e_i) + \kappa_i^2\,u .
$$
Her …
16
votes
Accepted
Are there some intrinsic invariants of surfaces other than Gaussian curvature?
As others have pointed out, it's not hard to show that any function $F(\kappa_1,\kappa_2)$ that is intrinsic to the surface metric must be a function of $K = \kappa_1\kappa_2$, so that settles what on …
14
votes
Accepted
A variant of the Monge-Cayley-Salmon theorem?
Setting aside the assumption that $\phi$ be a polynomial mapping for the moment (however, see below for a construction of a large family of polynomial solutions), if one makes the 'nondegeneracy' assu …
12
votes
Geometric meaning of derivatives of the curvature
This is not really an answer, but it's too long for a comment, so I'm posting it this way. One way in which the expression you are considering has appeared in recent years is via the heat equation sh …
8
votes
Accepted
homogeneous surface in $\mathbb{R}^4$
I'm rearranging my answer a little bit because I realized that I overlooked an apparent possibility (that turns out not to occur), and I didn't want my answer to be misleading:
If the surface in Eucl …
7
votes
Accepted
Construction of a linear Weingarten surface from a space curve
You'll find a discussion of the analysis of linear Weingarten surfaces via exterior differential systems in these lecture notes of mine. Particularly look at Section 5.1, where it is discussed at len …
7
votes
If a triangle can be displaced without distortion, must the surface have constant curvature?
This is sort of an answer and sort of not. I'll let you be the judge:
Suppose you formulate the question, not in terms of 'motion' (which you left vague) but terms of 'freely copying' a triangle $T$ …
6
votes
Minimal surface as varities
I assume that you are asking for a proof of the Weierstrass-Enneper representation theorem that, roughly speaking, tells you how to express solutions of the minimal surface equation in terms of holomo …
6
votes
Accepted
Can every smooth space curve be realized as an origami curved crease?
Note: I'm revising my answer to make the argument/construction more transparent. In the previous version, I stated an existence result about flat surfaces, but didn't indicate a proof (because, at th …
5
votes
Accepted
The class of uniformly accelerated curves and surfaces
I don't know what you might mean by 'uniformly accelerated surface', but I think that, by 'uniformly accelerated curve', you mean a curve in the plane parametrized in such a way that its velocity at t …