Results 261 to 270 of about 238,303 (293)

Hypervirial Theorems and Perturbation Theory

1987
In Appendix IV we present perturbation theory (PT) in such a way that degenerate systems may be studied without further difficulties and we show how the equations corresponding to the Rayleigh-Schrodinger Perturbation Theory (RSPT) [1] can be derived. Since this last methodology is considered in this chapter, we deem convenient to deduce here the main ...
F. M. Fernández, E. A. Castro
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Perturbation theorems for maximal \(L_p\)-regularity

2001
The authors consider perturbation theorems for \(R\)-sectorial operators. Let \(A\) be an \(R\)-sectorial operator in a Banach space \(X\). Let \(B\) be a perturbation for \(A\) which is relatively small with respect to \(A\). Then \(A+B\) is also \(R\)-sectorial. This result seems to be a generalization of the Kato-Rellich Theorem and the KLMN-Theorem.
Kunstmann, Peer Christian, Weis, Lutz
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Some theorems on perturbation theory

Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences, 1949
It is proved that the well-known formulae which give the variation in the eigenvalues and eigenfunctions arising from a differential equation Φ (x) + {λ — q(x)} Φ(x) = 0, when q(x) is varied, are valid under certain general conditions.
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Chiral Perturbation Theory and Final-State Theorem

Physical Review Letters, 1988
Timelike scalar and vector form factors are recalculated by use of chiral perturbation theory and dispersion theory. It is shown that chiral perturbation theory at the one-loop level violates the final-state theorem (i.e., unitarity). In order to satisfy this theorem, chiral perturbation theory should be applied to the inverse of the form factor whose ...
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Some Perturbation Theorems for Q-Matrices

SIAM Journal on Applied Mathematics, 1976
Given a real $n \times n$ matrix M and vector q, the linear complementarily problem is to find vectors w and z such that $w - Mz = q$, $w\geqq 0$, $z\geqq 0$, $w^t z = 0$. M is nondegenerate if all its principal minors are nonzero, and is a Q-matrix if the above problem has a solution for all $q \in E^n $.
openaire   +1 more source

Learning nonlinear operators via DeepONet based on the universal approximation theorem of operators

Nature Machine Intelligence, 2021
Lu Lu, Pengzhan Jin, Guofei Pang
exaly  

Three theorems on perturbed KdV

2008
This short paper is based on a lecture, given at the NATO Advanced Study Institute on Hamiltonian dynamical systems (Montréal, 2007). Its goal is to discuss three theorems on the long-time behaviour of solutions of a perturbed KdV equation under periodic boundary conditions.
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Experimental quantum key distribution certified by Bell's theorem

Nature, 2022
David Nadlinger, C j Ballance, Kirill Ivanov   +2 more
exaly  

A perturbation theorem

Acta Mathematica Academiae Scientiarum Hungaricae, 1973
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Weyl's type theorems and perturbations

2007
Summary: Weyl's theorem for a bounded linear operator \(T\) on complex Banach spaces, as well as its variants, a-Weyl's theorem and property (w), in general is not transmitted to a perturbation \(T + K\), even when \(K\) is a ``good'' operator, such as a commuting finite rank operator or a compact operator.
AIENA, Pietro, GUILLEN J, PENA P.
openaire   +2 more sources