The Experts below are selected from a list of 40365 Experts worldwide ranked by ideXlab platform
Norbert Van Den Bergh - One of the best experts on this subject based on the ideXlab platform.
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petrov type i silent universes with g3 isometry group the Uniqueness Result recovered
Classical and Quantum Gravity, 2006Co-Authors: Lode Wylleman, Norbert Van Den BerghAbstract:Irrotational dust spacetimes with vanishing magnetic Weyl curvature are called silent universes (Matarrese et al 1994 Phys. Rev. D 72 320). The silent universe conjecture (Sopuerta 1997 Phys. Rev. D 55 5936, van Elst et al 1997 Class. Quantum Grav. 14 1151) states that the only algebraically general silent universes are the orthogonally spatially homogeneous Bianchi I models. In the same paper by Sopuerta, this was confirmed for the subcase where the spacetime also admits a group G3 of isometries. However, the proof contains a conceptual mistake. We recover the Result in a different way.
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petrov type i silent universes with g3 isometry group the Uniqueness Result recovered
arXiv: General Relativity and Quantum Cosmology, 2005Co-Authors: Lode Wylleman, Norbert Van Den BerghAbstract:The \emph{silent universe conjecture} (Sopuerta 1997, van Elst et al. 1997) states that the only algebraically general silent universes are the orthogonally spatially homogeneous Bianchi I models. In the same paper by Sopuerta this was confirmed for the subcase where the spacetime also admits a group G3 of isometries. However the proof contains a conceptual mistake. We recover the Result in a different way.
Farid Bozorgnia - One of the best experts on this subject based on the ideXlab platform.
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Uniqueness Result for Long Range Spatially Segregation Elliptic System
Acta Applicandae Mathematicae, 2018Co-Authors: Farid BozorgniaAbstract:We study a class of elliptic competition-diffusion systems of long range segregation models for two and more competing species. We prove the Uniqueness Result for positive solution of those elliptic and related parabolic systems when the coupling in the right hand side involves a non-local term of integral form. Moreover, alternate proofs of some known Results, such as existence of solutions in the elliptic case and the limiting configuration are given. The free boundary condition in a particular setting is given.
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Uniqueness Result for Long Range Spatially Segregation Elliptic System
Acta Applicandae Mathematicae, 2017Co-Authors: Farid BozorgniaAbstract:We study a class of elliptic competition-diffusion systems of long range segregation models for two and more competing species. We prove the Uniqueness Result for positive solution of those elliptic and related parabolic systems when the coupling in the right hand side involves a non-local term of integral form.
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Uniqueness Result for long range spatially segregation elliptic system
arXiv: Analysis of PDEs, 2016Co-Authors: Farid BozorgniaAbstract:We study a class of elliptic competition-diffusion systems of long range segregation models for two and more competing species. The existence and Uniqueness of the solution are shown. We prove that as the competition rate goes to infinity the solution converges, along with suitable sequences, to a spatially long range segregated state satisfying some free boundary problems.
Lode Wylleman - One of the best experts on this subject based on the ideXlab platform.
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petrov type i silent universes with g3 isometry group the Uniqueness Result recovered
Classical and Quantum Gravity, 2006Co-Authors: Lode Wylleman, Norbert Van Den BerghAbstract:Irrotational dust spacetimes with vanishing magnetic Weyl curvature are called silent universes (Matarrese et al 1994 Phys. Rev. D 72 320). The silent universe conjecture (Sopuerta 1997 Phys. Rev. D 55 5936, van Elst et al 1997 Class. Quantum Grav. 14 1151) states that the only algebraically general silent universes are the orthogonally spatially homogeneous Bianchi I models. In the same paper by Sopuerta, this was confirmed for the subcase where the spacetime also admits a group G3 of isometries. However, the proof contains a conceptual mistake. We recover the Result in a different way.
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petrov type i silent universes with g3 isometry group the Uniqueness Result recovered
arXiv: General Relativity and Quantum Cosmology, 2005Co-Authors: Lode Wylleman, Norbert Van Den BerghAbstract:The \emph{silent universe conjecture} (Sopuerta 1997, van Elst et al. 1997) states that the only algebraically general silent universes are the orthogonally spatially homogeneous Bianchi I models. In the same paper by Sopuerta this was confirmed for the subcase where the spacetime also admits a group G3 of isometries. However the proof contains a conceptual mistake. We recover the Result in a different way.
Jose M Velhinho - One of the best experts on this subject based on the ideXlab platform.
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quantum gowdy t3 model a Uniqueness Result
Classical and Quantum Gravity, 2006Co-Authors: Alejandro Corichi, J Cortez, Guillermo Mena A Marugan, Jose M VelhinhoAbstract:Modulo a homogeneous degree of freedom and a global constraint, the linearly polarized Gowdy T 3 cosmologies are equivalent to a free scalar field propagating in a fixed nonstationary background. Recently, a new field parametrization was proposed for the metric of the Gowdy spacetimes such that the associatedscalarfieldevolves in a flat background in (1+1) dimensions with the spatial topology of S 1 , although subject to a time-dependent potential. Introducing a suitable Fock quantization for this scalar field, a quantum theory was constructed for the Gowdy model in which the dynamics is implemented as a unitary transformation. A question that was left open is whether one might adopt a different, nonequivalent Fock representation by selecting a distinct complex structure. The present work proves that the chosen Fock quantization is in fact unique (up to unitary equivalence) if one demands unitary implementation of the dynamics and invariance under the group of S translations. These translations are precisely those generated by the global constraint that remains on the Gowdy model. It is also shown that the proof of Uniqueness in the choice of the complex structure can be applied to more general field dynamics than that corresponding to the Gowdy cosmologies.
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quantum gowdy t 3 model a Uniqueness Result
arXiv: General Relativity and Quantum Cosmology, 2006Co-Authors: Alejandro Corichi, J Cortez, Guillermo Mena A Marugan, Jose M VelhinhoAbstract:Modulo a homogeneous degree of freedom and a global constraint, the linearly polarised Gowdy $T^3$ cosmologies are equivalent to a free scalar field propagating in a fixed nonstationary background. Recently, a new field parameterisation was proposed for the metric of the Gowdy spacetimes such that the associated scalar field evolves in a flat background in 1+1 dimensions with the spatial topology of $S^1$, although subject to a time dependent potential. Introducing a suitable Fock quantisation for this scalar field, a quantum theory was constructed for the Gowdy model in which the dynamics is implemented as a unitary transformation. A question that was left open is whether one might adopt a different, nonequivalent Fock representation by selecting a distinct complex structure. The present work proves that the chosen Fock quantisation is in fact unique (up to unitary equivalence) if one demands unitary implementation of the dynamics and invariance under the group of constant $S^1$ translations. These translations are precisely those generated by the global constraint that remains on the Gowdy model. It is also shown that the proof of Uniqueness in the choice of complex structure can be applied to more general field dynamics than that corresponding to the Gowdy cosmologies.
Alejandro Corichi - One of the best experts on this subject based on the ideXlab platform.
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quantum gowdy t3 model a Uniqueness Result
Classical and Quantum Gravity, 2006Co-Authors: Alejandro Corichi, J Cortez, Guillermo Mena A Marugan, Jose M VelhinhoAbstract:Modulo a homogeneous degree of freedom and a global constraint, the linearly polarized Gowdy T 3 cosmologies are equivalent to a free scalar field propagating in a fixed nonstationary background. Recently, a new field parametrization was proposed for the metric of the Gowdy spacetimes such that the associatedscalarfieldevolves in a flat background in (1+1) dimensions with the spatial topology of S 1 , although subject to a time-dependent potential. Introducing a suitable Fock quantization for this scalar field, a quantum theory was constructed for the Gowdy model in which the dynamics is implemented as a unitary transformation. A question that was left open is whether one might adopt a different, nonequivalent Fock representation by selecting a distinct complex structure. The present work proves that the chosen Fock quantization is in fact unique (up to unitary equivalence) if one demands unitary implementation of the dynamics and invariance under the group of S translations. These translations are precisely those generated by the global constraint that remains on the Gowdy model. It is also shown that the proof of Uniqueness in the choice of the complex structure can be applied to more general field dynamics than that corresponding to the Gowdy cosmologies.
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quantum gowdy t 3 model a Uniqueness Result
arXiv: General Relativity and Quantum Cosmology, 2006Co-Authors: Alejandro Corichi, J Cortez, Guillermo Mena A Marugan, Jose M VelhinhoAbstract:Modulo a homogeneous degree of freedom and a global constraint, the linearly polarised Gowdy $T^3$ cosmologies are equivalent to a free scalar field propagating in a fixed nonstationary background. Recently, a new field parameterisation was proposed for the metric of the Gowdy spacetimes such that the associated scalar field evolves in a flat background in 1+1 dimensions with the spatial topology of $S^1$, although subject to a time dependent potential. Introducing a suitable Fock quantisation for this scalar field, a quantum theory was constructed for the Gowdy model in which the dynamics is implemented as a unitary transformation. A question that was left open is whether one might adopt a different, nonequivalent Fock representation by selecting a distinct complex structure. The present work proves that the chosen Fock quantisation is in fact unique (up to unitary equivalence) if one demands unitary implementation of the dynamics and invariance under the group of constant $S^1$ translations. These translations are precisely those generated by the global constraint that remains on the Gowdy model. It is also shown that the proof of Uniqueness in the choice of complex structure can be applied to more general field dynamics than that corresponding to the Gowdy cosmologies.
