scholarly journals Correction to: Indefinite Abstract Splines with a Quadratic Constraint

Author(s):  
Santiago Gonzalez Zerbo ◽  
Alejandra Maestripieri ◽  
Francisco Martínez Pería
Keyword(s):  
1980 ◽  
Vol 36 (3) ◽  
pp. 291-307 ◽  
Author(s):  
Walter Gander

2021 ◽  
Vol 81 (12) ◽  
Author(s):  
Theodoros Pailas ◽  
Nikolaos Dimakis ◽  
Petros A. Terzis ◽  
Theodosios Christodoulakis

AbstractThe system under study is the $$\Lambda $$ Λ -Kantowski–Sachs universe. Its canonical quantization is provided based on a recently developed method: the singular minisuperspace Lagrangian describing the system, is reduced to a regular (by inserting into the dynamical equations the lapse dictated by the quadratic constraint) possessing an explicit (though arbitrary) time dependence; thus a time-covariant Schrödinger equation arises. Additionally, an invariant (under transformations $$t=f({\tilde{t}})$$ t = f ( t ~ ) ) decay probability is defined and thus “observers” which correspond to different gauge choices obtain, by default, the same results. The time of decay for a Gaussian wave packet localized around the point $$a=0$$ a = 0 (where a the radial scale factor) is calculated to be of the order $$\sim 10^{-42}{-}10^{-41}~\text {s}$$ ∼ 10 - 42 - 10 - 41 s . The acquired value is near the end of the Planck era (when comparing to a FLRW universe), during which the quantum effects are most prominent. Some of the results are compared to those obtained by following the well known canonical quantization of cosmological systems, i.e. the solutions of the Wheeler–DeWitt equation.


2018 ◽  
Vol 9 (10) ◽  
pp. 1011-1019 ◽  
Author(s):  
Qinghong Sheng ◽  
Qi Wang ◽  
Ran Hong ◽  
Bo Wang ◽  
Bin Zhang

2020 ◽  
Vol 32 (3) ◽  
pp. 763-778
Author(s):  
Zhuqi Miao ◽  
Balabhaskar Balasundaram

A γ-quasi-clique in a simple undirected graph refers to a subset of vertices that induces a subgraph with edge density at least γ. When γ equals one, this definition corresponds to a classical clique. When γ is less than one, it relaxes the requirement of all possible edges by the clique definition. Quasi-clique detection has been used in graph-based data mining to find dense clusters, especially in large-scale error-prone data sets in which the clique model can be overly restrictive. The maximum γ-quasi-clique problem, seeking a γ-quasi-clique of maximum cardinality in the given graph, can be formulated as an optimization problem with a linear objective function and a single quadratic constraint in binary variables. This article investigates the Lagrangian dual of this formulation and develops an upper-bounding technique using the geometry of ellipsoids to bound the Lagrangian dual. The tightness of the upper bound is compared with those obtained from multiple mixed-integer programming formulations of the problem via experiments on benchmark instances.


1998 ◽  
Vol 8 (1) ◽  
pp. 105-122 ◽  
Author(s):  
Stefano Lucidi ◽  
Laura Palagi ◽  
Massimo Roma

1987 ◽  
Vol 10 (1-2) ◽  
pp. 75-90 ◽  
Author(s):  
L. Martein ◽  
S. Schaible

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