Search results for "Tubular neighborhood"

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Voisinages tubulaires épointés et homotopie stable à l'infini

2022

We initiate a study of punctured tubular neighborhoods and homotopy theory at infinity in motivic settings. We use the six functors formalism to give an intrinsic definition of the stable motivic homotopy type at infinity of an algebraic variety. Our main computational tools include cdh-descent for normal crossing divisors, Euler classes, Gysin maps, and homotopy purity. Under-adic realization, the motive at infinity recovers a formula for vanishing cycles due to Rapoport-Zink; similar results hold for Steenbrink's limiting Hodge structures and Wildeshaus' boundary motives. Under the topological Betti realization, the stable motivic homotopy type at infinity of an algebraic variety recovers…

links of singularities[MATH.MATH-AG] Mathematics [math]/Algebraic Geometry [math.AG]Motivic homotopy theorypunctured tubular neighborhoods[MATH.MATH-AT] Mathematics [math]/Algebraic Topology [math.AT]stable homotopy at infinityMathematics::Algebraic TopologyMathematics - Algebraic Geometrylinks of singularities.Mathematics::Algebraic Geometryquadratic invariantsMathematics::K-Theory and HomologyFOS: MathematicsAlgebraic Topology (math.AT)14F42 19E15 55P42 14F45 55P57Mathematics - Algebraic TopologyAlgebraic Geometry (math.AG)qua- dratic invariants
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On the volume of unit vector fields on spaces of constant sectional curvature

2004

A unit vector field X on a Riemannian manifold determines a submanifold in the unit tangent bundle. The volume of X is the volume of this submanifold for the induced Sasaki metric. It is known that the parallel fields are the trivial minima.

Parallelizable manifoldGeneral MathematicsGEOMETRIA RIEMANNIANAMathematical analysisRiemannian manifoldSubmanifoldNormal bundleUnit tangent bundleMathematics::Differential GeometrySectional curvatureMathematics::Symplectic GeometryTangential and normal componentsTubular neighborhoodMathematics
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