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  2. PSA TU engine - Wikipedia

    en.wikipedia.org/wiki/PSA_TU_engine

    The TU engine is distantly related to the older X-Type engine — sharing a similar overhead camshaft architecture, but the key differences are the belt driven camshaft (the X is chain driven), and that the TU is mounted in a conventional upright position with a separate, end-on mounted transmission and unequal length drive shafts.

  3. Tubular neighborhood - Wikipedia

    en.wikipedia.org/wiki/Tubular_neighborhood

    In mathematics, a tubular neighborhood of a submanifold of a smooth manifold is an open set around it resembling the normal bundle. The idea behind a tubular neighborhood can be explained in a simple example. Consider a smooth curve in the plane without self-intersections. On each point on the curve draw a line perpendicular to the curve ...

  4. Seifert fiber space - Wikipedia

    en.wikipedia.org/wiki/Seifert_fiber_space

    The manifolds have Euclidean Thurston geometry if they are non-orientable or if b + Σb i /a i = 0, and nil geometry otherwise. Equivalently, the manifold has Euclidean geometry if and only if its fundamental group has an abelian group of finite index. There are 10 Euclidean manifolds, but four of them have two different Seifert fibrations.

  5. De Rham cohomology - Wikipedia

    en.wikipedia.org/wiki/De_Rham_cohomology

    Vector field corresponding to a differential form on the punctured plane that is closed but not exact, showing that the de Rham cohomology of this space is non-trivial.. In mathematics, de Rham cohomology (named after Georges de Rham) is a tool belonging both to algebraic topology and to differential topology, capable of expressing basic topological information about smooth manifolds in a form ...

  6. Category of manifolds - Wikipedia

    en.wikipedia.org/wiki/Category_of_manifolds

    The objects of Man • p are pairs (,), where is a manifold along with a basepoint , and its morphisms are basepoint-preserving p-times continuously differentiable maps: e.g. : (,) (,), such that () =. [1] The category of pointed manifolds is an example of a comma category - Man • p is exactly ({}), where {} represents an arbitrary singleton ...

  7. Connected sum - Wikipedia

    en.wikipedia.org/wiki/Connected_sum

    The connected sum is a local operation on manifolds, meaning that it alters the summands only in a neighborhood of . This implies, for example, that the sum can be carried out on a single manifold containing two disjoint copies of , with the effect of gluing to itself. For example, the connected sum of a 2-sphere at two distinct points of the ...

  8. Differentiable manifold - Wikipedia

    en.wikipedia.org/wiki/Differentiable_manifold

    Let M be a topological space.A chart (U, φ) on M consists of an open subset U of M, and a homeomorphism φ from U to an open subset of some Euclidean space R n.Somewhat informally, one may refer to a chart φ : U → R n, meaning that the image of φ is an open subset of R n, and that φ is a homeomorphism onto its image; in the usage of some authors, this may instead mean that φ : U → R n ...

  9. Good cover (algebraic topology) - Wikipedia

    en.wikipedia.org/wiki/Good_cover_(algebraic...

    A major reason for the notion of a good cover is that the Leray spectral sequence of a fiber bundle degenerates for a good cover, and so the Čech cohomology associated with a good cover is the same as the Čech cohomology of the space.