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41.
Miklós Simonovits 《Mathematical Programming》2003,97(1-2):337-374
In some areas of theoretical computer science we feel that randomized algorithms are better and in some others we can prove that they are more efficient than the deterministic ones.
Approximating the volume of a convex n-dimensional body, given by an oracle is one of the areas where this difference can be proved. In general, if we use a deterministic
algorithm to approximate the volume, it requires exponentially many oracle questions in terms of n as n→∞. Dyer, Frieze and Kannan gave a randomized polynomial approximation algorithm for the volume of a convex body K⊆ℝ
n
, given by a membership oracle.
The DKF algorithm was improved in a sequence of papers. The area is full of deep and interesting problems and results. This
paper is an introduction to this field and also a survey.
Received: January 28, 2003 / Accepted: April 29, 2003
Published online: May 28, 2003 相似文献
42.
A micro-miniature array of sensing capsules for optical monitoring of pH, potassium and glucose is described. Optode technology translates the respective ionic levels into variable colors of ionophore/dye/polymeric liquid micro-beads stuffed into individual capsules. Glucose is monitored indirectly, by coupling through glucose oxidase (GOX) immobilized in cellulose acetate phthalate (CAP) based microscopic beads that are stuffed into another microcapsule together with pH sensitive optical microscopic beads. The electrolyte and glucose sensing capsules are embedded in a transparent cellulose acetate bar 300-500 microm wide and 2-2.5 mm long called the sliver sensor that includes also a white capsule made of micro-beads without dye for optical reference. By adding further capsules custom combinations of analytes can be monitored in biomedical and non-biological contexts. In this work, as an example, design, fabrication and testing of a sliver sensor that could be developed for in vivo use are described. 相似文献
43.
Modifying the shape of FB-spline curves 总被引:1,自引:0,他引:1
FB-spline curves are the unification of recently developed trigonometric CB-spline and hyperbolic HB-spline curves, including the classical B-spline curves. These generalized curves overcome some restrictions of B-spline curves and allow to design some important curves like helix, cycloids or catenary. Their properties, however, have been studied only theoretically. In this paper practical shape modification algorithms of FB-spline curves are discussed, including the geometrical effects of the alteration of shape parameters, which are essential from the users’ point of view. 相似文献
44.
We study pre-equilibrium strangeness production at RHIC energies in a new parton cascade. Starting with the turbulent glue HIJING initial conditions we investigate the interplay between mini-jet and soft beam jet gluons for strangeness production prior to hadronization, and show the importance of soft beam jet gluons in the strangeness production. 相似文献
45.
Miklós Csörgő 《Journal of multivariate analysis》1979,9(1):84-100
Hoeffding (Ann. Math. Statist. 1948) and Blum, Kiefer and Rosenblatt (Ann. Math. Statist. 1961) constructed distribution free tests of independence based on a multivariate empirical process. We establish strong invariance principles for the latter and also for appropriate functionals of it. 相似文献
46.
Miklós Ajtai János Komlós Endre Szemerédi 《Journal of Combinatorial Theory, Series A》1980,29(3):354-360
Upper bounds are found for the Ramsey function. We prove and, for each k ? 3, asymptotically in x. 相似文献
47.
The set \({{\mathrm{Quo}}}(\mathbf {A})\) of compatible quasiorders (reflexive and transitive relations) of an algebra \(\mathbf {A}\) forms a lattice under inclusion, and the lattice \({{\mathrm{Con}}}(\mathbf {A})\) of congruences of \(\mathbf {A}\) is a sublattice of \({{\mathrm{Quo}}}(\mathbf {A})\). We study how the shape of congruence lattices of algebras in a variety determine the shape of quasiorder lattices in the variety. In particular, we prove that a locally finite variety is congruence distributive [modular] if and only if it is quasiorder distributive [modular]. We show that the same property does not hold for meet semi-distributivity. From tame congruence theory we know that locally finite congruence meet semi-distributive varieties are characterized by having no sublattice of congruence lattices isomorphic to the lattice \(\mathbf {M}_3\). We prove that the same holds for quasiorder lattices of finite algebras in arbitrary congruence meet semi-distributive varieties, but does not hold for quasiorder lattices of infinite algebras even in the variety of semilattices. 相似文献
48.
Steve Butler Fan Chung Ron Graham Miklós Laczkovich 《Discrete and Computational Geometry》2010,44(4):896-903
Given a simple polygon with rational coordinates having one vertex at the origin and an adjacent vertex on the x-axis, we look at the problem of the location of the vertices for a tiling of the polygon using lattice triangles (i.e., triangles
which are congruent to a triangle with the coordinates of the vertices being integer). We show that the coordinates of the
vertices in any tiling are rationals with the possible denominators odd numbers dependent on the cotangents of the angles
in the triangles. 相似文献
49.
An efficient solution approach for real-world driver scheduling problems in urban bus transportation
The driver scheduling problem in public transportation is defined in the following way. There is a set of operational tasks, and the goal is to define the sequence of these tasks as shifts in such a way that every task must be assigned to a shift without overlapping. In real-world situations several additional constraints need to be considered, which makes large practical problems challenging to be solved efficiently. In practice it is also an important request with respect to a public transportation scheduling system to offer several versions of quasi-optimal solutions. In this paper we present an efficient driver scheduling solution methodology which is flexible in the above sense. 相似文献
50.
Aleksandar Savić Roland Kardos Miklós Nyitrai Ksenija Radotić 《Journal of fluorescence》2013,23(3):605-610
Despite of widely application of multivariate analysis in chemometrics, problem of resolving closely positioned components in the fluorescence spectra remained unsolved, thus limiting the usage of fluorescence spectroscopy in analytical purpose. In this paper we have described a novel procedure, adapted especially for the analysis of complex fluorescence spectra with multiple, closely positioned components’ maxima. The method was first tested on the simulated spectra and then applied on the spectra of proteins whose fluorophores have similar properties of both the excitation and the emission spectra. In this paper, simple but efficient modification of the method was applied. Instead of analyzing full size emission matrix (12 spectra), 9 spectra wide windows were analyzed, and 4 factors (greatest possible number of factors with physical meaning both for actin and simulated spectra) were extracted in each pass. Obtained factor scores were grouped by using the K-means algorithm. Groups of factor scores obtained from K-means algorithm were passed through the one more factor analysis (FA) in order to find one factor that represents each group. Our approach provides resolution of extremely closed spectral components, which is a vital data for protein conformation analysis based on fluorescence spectroscopy. 相似文献