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This is called a trivial bundle. Examples of non-trivial fiber bundles include the Möbius strip and Klein bottle, as well as nontrivial covering spaces. Fiber bundles, such as the tangent bundle of a manifold and other more general vector bundles, play an important role in differential geometry and differential topology, as do principal bundles.
Vertical and horizontal subspaces for the Möbius strip. The Möbius strip is a line bundle over the circle, and the circle can be pictured as the middle ring of the strip. . At each point on the strip, the projection map projects it towards the middle ring, and the fiber is perpendicular to the middle ri
Discovered by Heinz Hopf in 1931, it is an influential early example of a fiber bundle. Technically, Hopf found a many-to-one continuous function (or "map") from the 3 -sphere onto the 2 -sphere such that each distinct point of the 2 -sphere is mapped from a distinct great circle of the 3 -sphere ( Hopf 1931 ). [ 1 ]
The Möbius strip can be constructed by a non-trivial gluing of two trivial bundles on open subsets U and V of the circle S 1.When glued trivially (with g UV =1) one obtains the trivial bundle, but with the non-trivial gluing of g UV =1 on one overlap and g UV =-1 on the second overlap, one obtains the non-trivial bundle E, the Möbius strip.
A mapping : between total spaces of two fibrations : and : with the same base space is a fibration homomorphism if the following diagram commutes: . The mapping is a fiber homotopy equivalence if in addition a fibration homomorphism : exists, such that the mappings and are homotopic, by fibration homomorphisms, to the identities and . [2]: 405-406
That surface has three I-bundles: the trivial bundle and two twisted bundles. Together with the Seifert fiber spaces, I-bundles are fundamental elementary building blocks for the description of three-dimensional spaces. These observations are simple well known facts on elementary 3-manifolds. Line bundles are both I-bundles and vector bundles ...
The Hopf fibration is an example of a non-trivial circle bundle. The unit tangent bundle of a surface is another example of a circle bundle. The unit tangent bundle of a non-orientable surface is a circle bundle that is not a principal () bundle. Only orientable surfaces have principal unit tangent bundles.
For a fiber bundle with structure group , the transition functions of the fiber (i.e., the cocycle) in an overlap of two coordinate systems and are given as a -valued function on . One may then construct a fiber bundle F ′ {\displaystyle F'} as a new fiber bundle having the same transition functions, but possibly a different fiber.