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201.
János Balogh József Békési Gábor Galambos Gerhard Reinelt 《Journal of Combinatorial Optimization》2014,27(1):115-131
Semi-on-line algorithms for the bin-packing problem allow, in contrast to pure on-line algorithms, the use of certain types of additional operations for each step. Examples include repacking, reordering or lookahead before packing the items. Here we define and analyze a semi-on-line algorithm where for each step at most k items can be repacked, for some positive integer k. We prove that the upper bound for the asymptotic competitive ratio of the algorithm is a decreasing function of k, which tends to 3/2 as k goes to infinity. We also establish lower bounds for this ratio and show that the gap between upper and lower bounds is relatively small. 相似文献
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This article explores why women delay childbearing and increase their likelihood to remain childless in Spain, Italy, West
Germany and France. We take a macro–micro perspective and show that national institutions influence women’s life transitions,
in particular partnership and motherhood. For coupled women, we find two alternative modes out of childlessness. In countries
with high direct and indirect child costs, like Spain and Italy, entering a male-breadwinner couple or occupying a stable
and high-income position facilitates motherhood, while in the French context motherhood is most likely in a dual-earner partnership.
相似文献
205.
Summary MultiGaussian models have the intrinsic property of imposing very little continuity to extreme values. If the variable that
is being modeled is hydraulic conductivity and the processes being studied are groundwater flow and mass transport, the absence
of continuous paths of extreme values will have a retardation effect in the computed travel times. In the case of radionuclide
release of nuclear waste from a deep geological repository, underestimation of travel times may lead to unsafe decision making.
To demonstrate the impact of the low continuity of extreme value implicit to multiGaussian modes, travel times are computed
in a site similar to Finnsj?n-one of the sites in crystaline rock studied in Sweden-using two stochastic models with the same
histogram and covariance, one of them is multiGaussian, and the other is not and displays high connectivity of extreme high
values. The results show that the multiGaussian model leads to less conservative results than the non-multiGaussian one. Invoking
the parisimony principle to select a multiGaussian model as the simplest model that can be fully described by a mean value
and a covariance function should not be justification enough for such selection. If there is not enough data to characterize
the connectivity of the extreme values and therefore distriminate whether a multiGaussian model is appropriate or not, less
parismonious models must also be considered. 相似文献
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Rastislav Bednárik Silvia Valna Jana Filipova Silvia Rybarova Zdenka Danekova 《Innovation: The European Journal of Social Science Research》1996,9(3):331-353
This article provides basic information about the transformation process in Slovakia from 1989 to 1994. Presented are some of the major results of the SOCO survey and selected important social topics are analyzed. Sociological information about income, property, consumption, and expenditures of Slovak households is given, and the economic activities of Slovak households and peoples’ attitudes to the transformation process are discussed. The article also addresses who are the winners and losers of the transition in the context of rising poverty and changes in social policy. 相似文献
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Maximum-likelihood estimation is interpreted as a procedure for generating approximate pivotal quantities, that is, functions u(X;θ) of the data X and parameter θ that have distributions not involving θ. Further, these pivotals should be efficient in the sense of reproducing approximately the likelihood function of θ based on X, and they should be approximately linear in θ. To this end the effect of replacing θ by a parameter ϕ = ϕ(θ) is examined. The relationship of maximum-likelihood estimation interpreted in this way to conditional inference is discussed. Examples illustrating this use of maximum-likelihood estimation on small samples are given. 相似文献
210.