arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 2001.10245math.DGmath.SG
收藏

曲面族的等距

Equidistants for families of surfaces

Peter Giblin, Graham Reeve

摘要:

对于一个光滑的表面在$\mathbb{R}^3$这篇文章包含局部研究某些仿射等距,即在一个固定的比例之间的接触点的平行切面(但不包括比例0和1的等距包含一个或其他切触点)的点的轨迹。研究的情况一般发生在一个1参数的家庭,其中两个抛物点的表面有平行的切面在该唯一的渐近方向也是平行的。奇异性的分类,把等距线作为一个2-参数展开从$\mathbb{R}^4$到$\mathbb{R}^3$的地图的临界值。特别是,奇点附近发生的所谓的“超焦弦”,加入两个特殊的抛物点,进行了分类。对于一个给定的比率沿此弦的一个或三个特殊的点被确定,在这些点上的奇点的等距变得更加特殊。许多由此产生的奇异点之前已经在抽象分类的文献中出现过,因此本文还为这些奇异点提供了一个自然的几何设置,与它们所源自的表面的几何形状有关。

英文摘要:

For a smooth surface in $\mathbb{R}^3$ this article contains local study of certain affine equidistants, that is loci of points at a fixed ratio between points of contact of parallel tangent planes (but excluding ratios 0 and 1 where the equidistant contains one or other point of contact). The situation studied occurs generically in a 1-parameter family, where two parabolic points of the surface have parallel tangent planes at which the unique asymptotic directions are also parallel. The singularities are classified by regarding the equidistants as critical values of a 2-parameter unfolding of maps from $\mathbb{R}^4$ to $\mathbb{R}^3$. In particular, the singularities that occur near the so-called `supercaustic chord', joining the two special parabolic points, are classified. For a given ratio along this chord either one or three special points are identified at which singularities of the equidistant become more special. Many of the resulting singularities have occurred before in the literature in abstract classifications, so the article also provides a natural geometric setting for these singularities, relating back to the geometry of the surfaces from which they are derived.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑