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251.
Bo Ling 《Numerical Functional Analysis & Optimization》2013,34(6):724-738
We consider the optimal recovery problem of isotropic classes of r-th differentiable multivariate functions defined on ? d , and obtain some asymptotically optimal results. It turns out that this optimal recovery problem is intimately related to the optimal covering problem of ? d by equal balls in discrete geometry. 相似文献
252.
253.
Liquid–liquid equilibrium (LLE) data for different systems involving ionic liquids are essential for design, optimization and operation of separation processes, such as recovery of valuable products and remotion of polluting agents in effluents. In this work, the ASOG model for the activity coefficient is used to predict LLE data for 32 ternary systems at 101.3 kPa and several temperatures; all the systems are formed by ionic liquids including the tetrafluoroborate anion plus alkanes, alkenes, cycloalkanes, alkanols, ketones, carboxylic acids, esters and aromatics. New group interaction parameters were determined by using a modified Simplex method, minimizing a composition-based objective function. The results, in terms of mean deviation between the experimental and calculated compositions, are satisfactory, with rms deviations of about 4%. 相似文献
254.
Vladimir P. Fonf Clemente Zanco 《Journal of Mathematical Analysis and Applications》2009,350(2):640-650
A well-known result due to H. Corson states that, for any covering τ by closed bounded convex subsets of any Banach space X containing an infinite-dimensional reflexive subspace, there exists a compact subset C of X that meets infinitely many members of τ. We strengthen this result proving that, even under the weaker assumption that X contains an infinite-dimensional separable dual space, an (algebraically) finite-dimensional compact set C with that property can always be found. 相似文献
255.
A series is called a pointwise universal trigonometric series if for any , there exists a strictly increasing sequence of positive integers such that converges to f(z) pointwise on . We find growth conditions on coefficients allowing and forbidding the existence of a pointwise universal trigonometric series. For instance, if as |n|→∞ for some ε>0, then the series Sa cannot be pointwise universal. On the other hand, there exists a pointwise universal trigonometric series Sa with as |n|→∞. 相似文献
256.
Horst Martini 《Discrete Mathematics》2009,309(16):5158-5168
It is well known that the famous covering problem of Hadwiger is completely solved only in the planar case, i.e.: any planar convex body can be covered by four smaller homothetical copies of itself. Lassak derived the smallest possible ratio of four such homothets (having equal size), using the notion of regular 4-covering. We will continue these investigations, mainly (but not only) referring to centrally symmetric convex plates. This allows to interpret and derive our results in terms of Minkowski geometry (i.e., the geometry of finite dimensional real Banach spaces). As a tool we also use the notion of quasi-perfect and perfect parallelograms of normed planes, which do not differ in the Euclidean plane. Further on, we will use Minkowskian bisectors, different orthogonality types, and further notions from the geometry of normed planes, and we will construct lattice coverings of such planes and study related Voronoi regions and gray areas. Discussing relations to the known bundle theorem, we also extend Miquel’s six-circles theorem from the Euclidean plane to all strictly convex normed planes. 相似文献
257.
It is known that not all planar graphs are 4‐choosable; neither all of them are vertex 2‐arborable. However, planar graphs without 4‐cycles and even those without 4‐cycles adjacent to 3‐cycles are known to be 4‐choosable. We extend this last result in terms of covering the vertices of a graph by induced subgraphs of variable degeneracy. In particular, we prove that every planar graph without 4‐cycles adjacent to 3‐cycles can be covered by two induced forests. © 2009 Wiley Periodicals, Inc. J Graph Theory 62, 234–240, 2009 相似文献
258.
259.
Ling Gai 《Operations Research Letters》2009,37(2):89-92
We prove APX-hardness for the two problems maximum resource bin packing and lazy bin covering. Simple algorithms matching the best absolute bounds under the assumption P≠NP are also derived. 相似文献
260.
Let ∧ be the Z2-Galois covering of the Grassmann algebra A over a field k of characteristic not equal to 2. In this paper, the dimensional formulae of Hochschild homology and cohomology groups of ∧ are calculated explicitly. And the cyclic homology of∧ can also be calculated when the underlying field is of characteristic zero. As a result, we prove that there is an isomorphism from i≥1 HH^i(∧) to i≥1 HH^i(∧). 相似文献