1,828,279 research outputs found
Integrable Conformal Field Theory in Four Dimensions and Fourth-Rank Geometry
We consider the conformal properties of geometries described by higher-rank
line elements. A crucial role is played by the conformal Killing equation
(CKE). We introduce the concept of null-flat spaces in which the line element
can be written as . We then show that, for
null-flat spaces, the critical dimension, for which the CKE has infinitely many
solutions, is equal to the rank of the metric. Therefore, in order to construct
an integrable conformal field theory in 4 dimensions we need to rely on
fourth-rank geometry. We consider the simple model and show that it is an integrable conformal model in 4
dimensions. Furthermore, the associated symmetry group is .Comment: 17 pages, plain TE
On the intrinsic and the spatial numerical range
For a bounded function from the unit sphere of a closed subspace of a
Banach space , we study when the closed convex hull of its spatial numerical
range is equal to its intrinsic numerical range . We show that for
every infinite-dimensional Banach space there is a superspace and a
bounded linear operator such that . We also show that, up to renormig, for every non-reflexive Banach space
, one can find a closed subspace and a bounded linear operator such that .
Finally, we introduce a sufficient condition for the closed convex hull of
the spatial numerical range to be equal to the intrinsic numerical range, which
we call the Bishop-Phelps-Bollobas property, and which is weaker than the
uniform smoothness and the finite-dimensionality. We characterize strong
subdifferentiability and uniform smoothness in terms of this property.Comment: 12 page
Campo eléctrico y potencia eléctrico
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Campo magnético terresre
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Uso del osciloscopio
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Uso de instrumentos de medición eléctrica ( Parte I )
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Reglas de Kirchhoff
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