Talk:Development (differential geometry)

Cartan developments

Just to get some clarity about the purpose of this page, what would you suggest as the optimal route to Cartan developments of curves? Something like developments of curves in affine connection (which is clearly the linchpin of the whole Cartan connection treatment) -> Cartan connection (with various intermediate steps, such as projective connection and conformal connection as those pages mature). Silly rabbit 02:11, 21 April 2007 (UTC)[reply]

Assessment comment

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This article is intended to bridge between classical notions of development and modern formulations in terms of flat connections or isometries. Geometry guy 10:03, 13 April 2007 (UTC)[reply]

Last edited at 21:52, 14 April 2007 (UTC). Substituted at 01:59, 5 May 2016 (UTC)

Intro first sentence is nonsensical

"In classical differential geometry, development is the rolling one smooth surface over another in Euclidean space."

This is not grammatical and as a result doesn't convey useful information. Probably it is supposed to read "...the rolling of one..." but I don't know enough to know whether this is correct. Gwideman (talk) 23:19, 7 January 2025 (UTC)[reply]

Sphere: can participate in development or not?

Intro: "the tangent plane to a surface (such as the sphere or the cylinder) at a point can be rolled around the surface to obtain the tangent plane at other points."

Properties: "The tangential contact between the surfaces being rolled over one another provides a relation between points on the two surfaces. If this relation is (perhaps only in a local sense) a bijection between the surfaces, then the two surfaces are said to be developable on each other or developments of each other. Differently put, the correspondence provides an isometry, locally, between the two surfaces. In particular, if one of the surfaces is a plane, then the other is called a developable surface: thus a developable surface is one which is locally isometric to a plane. The cylinder is developable, but the sphere is not."

Why is the sphere not developable, when the intro uses a plane + sphere as an example of development (presumably locally)? Gwideman (talk) 23:28, 7 January 2025 (UTC)[reply]