Compact Osserman Manifolds with Neutral Metric

Brozos‐Vázquez, Miguel; Garcı́a-Rı́o, Eduardo; Gilkey, Peter Β.; Vázquez-Lorenzo, Ramón

doi:10.1007/s00025-011-0116-y

Cited by 1 publication

(3 citation statements)

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“…This follows from pulling back the neutral metric (3.3) to the hypersurface (3.12) and taking the determinant. The result is 4 , and the result follows.…”

Section: Tangent Hypersurfacesmentioning

confidence: 83%

“…ǫ . The space of oriented geodesics L(S 3 ǫ ) of (S 3 ǫ , g ǫ ) is 4-dimensional and L(S 3 1 ) can be identified with the Grasmannian of oriented planes in R 4 1 , while L(S 3 −1 ) can be identified with the Grasmannian of oriented planes in R 4 −1 such that the induced metric is Lorentzian [3].…”

Section: 21mentioning

confidence: 99%

“…As the discussion necessitates spanning a number of areas, the bibliography will be selective rather than exhaustive. Further aspects of neutral metrics which we do not discuss can be found foe example in [4] [7] [27] [28] and references therein.…”

Section: Neutral Causal Topologymentioning

confidence: 99%

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The causal topology of neutral 4-manifolds with null boundary

Georgiou,

Guilfoyle

2016

Preprint

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This paper considers aspects of 4-manifold topology from the point of view of the null cone of a neutral metric, a point of view we call neutral causal topology. In particular, we construct and investigate neutral 4-manifolds with null boundaries that arise from canonical 3-and 4-dimensional settings.A null hypersurface is foliated by its normal and, in the neutral case, inherits a pair of totally null planes at each point. This paper focuses on these plane bundles in a number of classical settingsThe first construction is the conformal compactification of flat neutral 4space into the 4-ball. The null foliation on the boundary in this case is the Hopf fibration on the 3-sphere and the totally null planes in the boundary are integrable. The metric on the 4-ball is a conformally flat, scalar-flat, positive Ricci curvature neutral metric.The second constructions are subsets of the 4-dimensional space of oriented geodesics in a 3-dimensional space-form, equipped with its canonical neutral metric. We consider all oriented geodesics tangent to a given embedded strictly convex 2-sphere. Both totally null planes on this null hypersurface are contact, and we characterize the curves in the null boundary that are Legendrian with respect to either totally null plane bundles. The Reeb vector field associated with the alpha-planes are shown to be the oriented normal lines to geodesics in the surface.The third is a neutral geometric model for the intersection of two surfaces in a 4-manifold. The surfaces are the sets of oriented normal lines to two round spheres in Euclidean 3-space, which form Lagrangian surfaces in the 4-dimensional space of all oriented lines. The intersection of the boundaries of their normal neighbourhoods form tori that we prove are totally real and Lorentz if the spheres do not intersect.We conclude with possible topological applications of the three constructions, including neutral Kirby calculus, neutral knot invariants and neutral Casson handles, respectively.

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“…This follows from pulling back the neutral metric (3.3) to the hypersurface (3.12) and taking the determinant. The result is 4 , and the result follows.…”

Section: Tangent Hypersurfacesmentioning

confidence: 83%

Section: 21mentioning

confidence: 99%

See 1 more Smart Citation

The causal topology of neutral 4-manifolds with null boundary

Georgiou,

Guilfoyle

2016

Preprint

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Compact Osserman Manifolds with Neutral Metric

Abstract: It is shown that if a compact four-dimensional manifold with metric of neutral signature is Jordan-Osserman, then it is either of constant sectional curvature or Ricci flat.Mathematics Subject Classification (2010). Primary 53C50; Secondary 53B30.

Cited by 1 publication

References 32 publications

The causal topology of neutral 4-manifolds with null boundary

The causal topology of neutral 4-manifolds with null boundary

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