| 释义 |
non-ˈorientable, a. Math.
[non- 3.]
Of a surface: such that a figure in the surface can be continuously transformed into its mirror image by taking it round a closed path in the surface; not orientable.
1949S. Lefschetz Introd. Topology ii. 76 The combination of the first type is called nonorientable. 1952P. Nemenyi tr. Hilbert & Cohn-Vossen's Geom. & Imagination vi. 306 The classification of surfaces into two-sided and one-sided surfaces is identical with the classification into orientable and non-orientable. Ibid., A surface is non-orientable if and only if there exists on the surface some closed curve s which is such that a small oriented circle whose center traverses the curve continuously will arrive at its starting point with its orientation reversed. 1965S. Barr Exper. Topology ii. 22 The Moebius strip is what is called non-orientable—which is less open to misinterpretation than saying it is 1-sided.
Hence ˌnon-orientaˈbility, the property of being non-orientable.
1949S. Lefschetz Introd. Topology ii. 83 A closed surface..is completely characterized by the value of its Betti number..and by its orientability or nonorientability. 1964H. Levy Projective & Related Geometries v. 388 We shall derive two properties of L2 that are strongly suggestive of its nonorientability. |