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  2. List of cohomology theories - Wikipedia

    en.wikipedia.org/wiki/List_of_cohomology_theories

    Coefficient ring: The coefficient groups π n (S) are the stable homotopy groups of spheres, which are notoriously hard to compute or understand for n > 0. (For n < 0 they vanish, and for n = 0 the group is Z.) Stable homotopy is closely related to cobordism of framed manifolds (manifolds with a trivialization of the normal bundle).

  3. Universal bundle - Wikipedia

    en.wikipedia.org/wiki/Universal_bundle

    If M is a paracompact manifold and P → M is a principal G-bundle, then there exists a map f : M → BG, unique up to homotopy, such that P is isomorphic to f ∗ (EG), the pull-back of the G-bundle EG → BG by f. Proof. On one hand, the pull-back of the bundle π : EG → BG by the natural projection P × G EG → BG is the bundle P × EG.

  4. Characteristic class - Wikipedia

    en.wikipedia.org/wiki/Characteristic_class

    The prime mechanism then appeared to be this: Given a space X carrying a vector bundle, that implied in the homotopy category a mapping from X to a classifying space BG, for the relevant linear group G. For the homotopy theory the relevant information is carried by compact subgroups such as the orthogonal groups and unitary groups of G.

  5. Stiefel manifold - Wikipedia

    en.wikipedia.org/wiki/Stiefel_manifold

    The vector bundles associated to these principal bundles via the natural action of G on are just the tautological bundles over the Grassmannians. In other words, the Stiefel manifold V k ( F n ) {\displaystyle V_{k}(\mathbb {F} ^{n})} is the orthogonal, unitary, or symplectic frame bundle associated to the tautological bundle on a Grassmannian.

  6. Stable normal bundle - Wikipedia

    en.wikipedia.org/wiki/Stable_normal_bundle

    A Poincaré space X does not have a tangent bundle, but it does have a well-defined stable spherical fibration, which for a differentiable manifold is the spherical fibration associated to the stable normal bundle; thus a primary obstruction to X having the homotopy type of a differentiable manifold is that the spherical fibration lifts to a ...

  7. Holonomy - Wikipedia

    en.wikipedia.org/wiki/Holonomy

    Computing the holonomy of Riemannian manifolds has been suggested as a way to learn the structure of data manifolds in machine learning, in particular in the context of manifold learning. As the holonomy group contains information about the global structure of the data manifold, it can be used to identify how the data manifold might decompose ...

  8. Homotopy principle - Wikipedia

    en.wikipedia.org/wiki/Homotopy_principle

    In mathematics, the homotopy principle (or h-principle) is a very general way to solve partial differential equations (PDEs), and more generally partial differential relations (PDRs). The h-principle is good for underdetermined PDEs or PDRs, such as the immersion problem, isometric immersion problem, fluid dynamics, and other areas.

  9. Plumbing (mathematics) - Wikipedia

    en.wikipedia.org/wiki/Plumbing_(mathematics)

    If the base manifold is an n-sphere , then by iterating this procedure over several vector bundles over one can plumb them together according to a tree [3] §8.If is a tree, we assign to each vertex a vector bundle over and we plumb the corresponding disk bundles together if two vertices are connected by an edge.