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71.
The main result of the present note states that it is consistent with the ZFC axioms of set theory (relying on Martin's Maximum MM axiom), that every Asplund space of density character ω1 has a renorming with the Mazur intersection property. Combined with the previous result of Jiménez and Moreno (based upon the work of Kunen under the continuum hypothesis) we obtain that the MIP renormability of Asplund spaces of density ω1 is undecidable in ZFC. 相似文献
72.
Costa et al. (Oper. Res. Lett. 31:21–27, 2003) presented a quadratic O(min (Kn,n
2)) greedy algorithm to solve the integer multicut and multiflow problems in a rooted tree. (n is the number of nodes of the tree, and K is the number of commodities). Their algorithm is a special case of the greedy type algorithm of Kolen (Location problems
on trees and in the rectilinear plane. Ph.D. dissertation, 1982) to solve weighted covering and packing problems defined by general totally balanced (greedy) matrices. In this communication
we improve the complexity bound in Costa et al. (Oper. Res. Lett. 31:21–27, 2003) and show that in the case of the integer multicut and multiflow problems in a rooted tree the greedy algorithm of Kolen
can be implemented in subquadratic O(K+n+min (K,n)log n) time. The improvement is obtained by identifying additional properties of this model which lead to a subquadratic transformation
to greedy form and using more sophisticated data structures.
相似文献
73.
Wenbin Lu 《Annals of the Institute of Statistical Mathematics》2008,60(3):545-574
The proportional hazards cure model generalizes Cox’s proportional hazards model which allows that a proportion of study subjects
may never experience the event of interest. Here nonparametric maximum likelihood approach is proposed to estimating the cumulative
hazard and the regression parameters. The asymptotic properties of the resulting estimators are established using the modern
empirical process theory. And the estimators for the regression parameters are shown to be semiparametric efficient. 相似文献
74.
In this paper, we show the results of an experimental study about the most important algorithms proposed to solve the Maximum
Flow problem. The appropriate statistical analysis not only allows us to justify comparisons between the different procedures
but also to obtain classifications of their practical efficiency. Furthermore, an empirical experiment allows us to identify
the influence of several parameters that are not included in a theoretical study. 相似文献
75.
The paper proposes a general optimization model with separable strictly convex objective function to obtain the consistent OWA (ordered weighted averaging) operator family. The consistency means that the aggregation value of the operator monotonically changes with the given orness level. Some properties of the problem are discussed with its analytical solution. The model includes the two most commonly used maximum entropy OWA operator and minimum variance OWA operator determination methods as its special cases. The solution equivalence to the general minimax problem is proved. Then, with the conclusion that the RIM (regular increasing monotone quantifier) can be seen as the continuous case of OWA operator with infinite dimension, the paper further proposes a general RIM quantifier determination model, and analytically solves it with the optimal control technique. Some properties of the optimal solution and the solution equivalence to the minimax problem for RIM quantifier are also proved. Comparing with that of the OWA operator problem, the RIM quantifier solutions are usually more simple, intuitive, dimension free and can be connected to the linguistic terms in natural language. With the solutions of these general problems, we not only can use the OWA operator or RIM quantifier to obtain aggregation value that monotonically changes with the orness level for any aggregated set, but also can obtain the parameterized OWA or RIM quantifier families in some specific function forms, which can incorporate the background knowledge or the required characteristic of the aggregation problems. 相似文献
76.
Vladimir M. Veliov 《Journal of Mathematical Analysis and Applications》2008,346(1):227-242
A general model of a heterogeneous control system is introduced in the form of a first order distributed system with nonlocal dynamics and exogenous side-conditions. The heterogeneity is represented by a parameter taking values in an abstract measurable space, so that both continuous and discrete heterogeneity, as well as probabilistic heterogeneity without density, are included. A distributed and a lumped controls are involved, the latter appearing also in the side conditions. An existence theorem is proved for the uncontrolled system, and the sensitivity of the solution with respect to the control variables is estimated. The main result is an optimality condition in the form of the Pontryagin local maximum principle. A global maximum principle holds for the distributed control under an additional condition that rules out discrete measurable heterogeneity spaces. A number of possible applications are outlined: age-structured systems, size-structured systems, (nonlocal) advection-reaction equations, static parametric heterogeneity in epidemiology, and two-stage control systems with uncertain switching time. 相似文献
77.
We study the maximum likelihood estimator for stochastic equations with additive fractional Brownian sheet. We use the Girsanov
transform for the the two-parameter fractional Brownian motion, as well as the Malliavin calculus and Gaussian regularity
theory.
相似文献
78.
Simple ingredients leading to very efficient heuristics for the maximum clique problem 总被引:2,自引:0,他引:2
Starting from an algorithm recently proposed by Pullan and Hoos, we formulate and analyze iterated local search algorithms
for the maximum clique problem. The basic components of such algorithms are a fast neighbourhood search (not based on node
evaluation but on completely random selection) and simple, yet very effective, diversification techniques and restart rules.
A detailed computational study is performed in order to identify strengths and weaknesses of the proposed algorithms and the
role of the different components on several classes of instances. The tested algorithms are very fast and reliable: most of
the DIMACS benchmark instances are solved within very short CPU times. For one of the hardest tests, a new putative optimum
was discovered by one of our algorithms. Very good performances were also shown on recently proposed and more difficult instances.
It is important to remark that the heuristics tested in this paper are basically parameter free (the appropriate value for
the unique parameter is easily identified and was, in fact, the same value for all problem instances used in this paper). 相似文献
79.
A study is made of an overtaking optimal problem for a population system consisting of two competing species, which is controlled by fertilities. The existence of optimal policy is proved and a maximum principle is carefully derived under less restrictive conditions. Weak and strong turnpike properties of optimal trajectories are established. 相似文献
80.
Shang Wei ZHU 《数学学报(英文版)》2006,22(2):607-624
In this paper, an optimal control problem for parabolic variational inequalities with delays in the highest order spatial derivatives is investigated. The well-posedness of such kinds of variational inequalities is established. The existence of optimal controls under a Cesari-type condition is proved, and the necessary conditions of Pontryagin type for optimal controls is derived. 相似文献