共查询到20条相似文献,搜索用时 390 毫秒
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Vladimir D. Tonchev 《Geometriae Dedicata》1993,48(3):295-308
It is proved that a quasi-symmetric design with theSymmetric Difference Property (SDP) is uniquely embeddable as a derived or a residual design into a symmetric SDP design. Alternatively, any quasi-symmetric SDP design is characterized as the design formed by the minimum weight vectors in a binary code spanned by the simplex code and the incidence vector of a point set in PG(2m-1, 2) that intersects every hyperplane in one of two prescribed numbers of points. Applications of these results for the classification of point sets in PG(2m-1, 2) with the same intersection properties as an elliptic or a hyperbolic quadric, as well as the classification of codes achieving the Grey-Rankin bound are discussed. 相似文献
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A. A. Makhnev M. S. Nirova D. V. Paduchikh 《Proceedings of the Steklov Institute of Mathematics》2016,293(1):101-119
The research is focused on the question of proportional development in economic growth modeling. A multilevel dynamic optimization model is developed for the construction of balanced proportions for production factors and investments in a situation of changing prices. At the first level, models with production functions of different types are examined within the classical static optimization approach. It is shown that all these models possess the property of proportionality: in the solution of product maximization and cost minimization problems, production factor levels are directly proportional to each other with coefficients of proportionality depending on prices and elasticities of production functions. At the second level, proportional solutions of the first level are transferred to an economic growth model to solve the problem of dynamic optimization for the investments in production factors. Due to proportionality conditions and the homogeneity condition of degree 1 for the macroeconomic production functions, the original nonlinear dynamics is converted to a linear system of differential equations that describe the dynamics of production factors. In the conversion, all peculiarities of the nonlinear model are hidden in a time-dependent scale factor (total factor productivity) of the linear model, which is determined by proportions between prices and elasticities of the production functions. For a control problem with linear dynamics, analytic formulas are obtained for optimal development trajectories within the Pontryagin maximum principle for statements with finite and infinite horizons. It is shown that solutions of these two problems differ crucially from each other: in finite horizon problems the optimal investment strategy inevitably has the zero regime at the final stage, whereas the infinite horizon problem always has a strictly positive solution. A remarkable result of the proposed model consists in constructive analytical solutions for optimal investments in production factors, which depend on the price dynamics and other economic parameters such as elasticities of production functions, total factor productivity, and depreciation factors. This feature serves as a background for the productive fusion of optimization models for investments in production factors in the framework of a multilevel structure and provides a solid basis for constructing optimal trajectories of economic development. 相似文献
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Magnitude is a numerical invariant of metric spaces introduced by Leinster, motivated by considerations from category theory. This paper extends the original definition for finite spaces to compact spaces, in an equivalent but more natural and direct manner than in previous works by Leinster, Willerton, and the author. The new definition uncovers a previously unknown relationship between magnitude and capacities of sets. Exploiting this relationship, it is shown that for a compact subset of Euclidean space, the magnitude dimension considered by Leinster and Willerton is equal to the Minkowski dimension. 相似文献
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Richard Haberman 《Studies in Applied Mathematics》1991,84(1):57-69
Oscillatory dispersive waves propagating in a slowly varying medium are analyzed for Klein-Gordon equations with perturbations. The method of multiple scales is extended to include two fast scales, the usual traveling-wave phase and time, in order to allow initial conditions not usually permitted. An exact wave-action equation is introduced if the traveling wave is stable, involving averages over the periodic wave as well as time. This is equivalent to an extended averaged Lagrangian principle. The equation for the slow modulations of the phase shift of the traveling wave is derived from the higher order terms in the exact action equation and is shown to be the same as in earlier more restrictive studies. 相似文献
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Self-expression,Expressiveness, and Sincerity 总被引:1,自引:0,他引:1
John Eriksson 《Acta Analytica》2010,25(1):71-79
This paper examines some aspects of Mitchell Green’s account of self-expression. I argue that Green fails to address the distinction
between success and evidential notions of expression properly, which prevents him from adequately discussing the relation
between these notions. I then consider Green’s explanation of how a speech act shows what is within, i.e., because of the
liabilities one incurs and argue that this is false. Rather, the norms governing speech acts and liabilities incurred give
us reason to think that the speaker is in a particular state of mind. It thus supports an evidential rather than success notion.
Finally, I suggest that it is because of the sincerity of what is said, rather than the liabilities incurred, that you show
what is within. 相似文献
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An algorithm incorporating features essential for practical,reliable, rational interpolation is explained. This algorithmgenerates a Thiele-Werner continued fraction representationof the interpolant. A backward error analysis is presented forthe algorithm, as well as for its special cases of Newton polynomialinterpolation and Thiele rational interpolation. This is madepossible by introducing into the Newton method, Thiele methodand Werner method a strategy for selecting the interpolationpoints in an optimal order. 相似文献
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Wave propagation in a transversally isotropic, elastic medium consisting of plane-parallel layers and half spaces is considered. A generalized matrix method is used to derive the dispersion equation of this medium and to find the coefficients of reflection and refraction. This method makes it possible to consider dispersion curves and the coeffients of reflection and refraction in a broader domain than with Haskell's method. The results obtained generalize to layers in which the elastic characteristics vary with depth according to an arbitrary law. For such layers it is possible to find matrices in the form of series which converge rapidly for low and high frequencies. Moreover, a rule is formulated which makes it possible on the basis of a known field in an isotropic medium to find the field in the corresponding transversally isotropic medium. 相似文献
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Stephan Morgenthaler John W. Tukey 《Journal of computational and graphical statistics》2013,22(1):180-195
Abstract This article introduces a family of distributional shapes which is flexible in the sense that it contains skewed and symmetric laws as well as heavy-tailed and light-tailed laws. The proposed family is also practically convenient because it is easy to fit to a table of quantiles from any distribution. Inversely, for each of the distributional shapes it is trivial to compute quantiles for any desired probability, and it is possible to compute the corresponding densities. 相似文献
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Kevin Purbhoo 《Journal of Algebraic Combinatorics》2008,28(4):461-480
We define mosaics, which are naturally in bijection with Knutson-Tao puzzles. We define an operation on mosaics, which shows
they are also in bijection with Littlewood-Richardson skew-tableaux. Another consequence of this construction is that we obtain
bijective proofs of commutativity and associativity for the ring structures defined either of these objects. In particular,
we obtain a new, easy proof of the Littlewood-Richardson rule. Finally we discuss how our operation is related to other known
constructions, particularly jeu de taquin. 相似文献
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Yannick Aoustin Alexander Formal’sky Christine Chevallereau 《Journal of Mathematical Sciences》2007,147(2):6552-6568
We consider a prototyped walking robot containing a platform and two double-link legs. Thus, it is a five-link mechanism.
The front leg models identical motions of the quadruped’s two front legs, and the back leg models identical motions of the
quadruped’s two back legs. The legs have passive (uncontrolled) feet that extend in the frontal plane. Because of this the
robot is stable in the frontal plane. This robot can be viewed as a “virtual” quadruped. Four DC motors drive the mechanism.
Its control system comprises a computer, hardware servo-systems, and power amplifiers. The locomotion of the prototype is
planar curvet gait. In the double support our prototype is statically stable and overactuated. In the single support it is an unstable
and underactuated system. There is no flight phase. We describe here the scheme of the mechanism, the characteristics of the
drives, and the control strategy. The dynamic model of the planar walking is recalled for the double-and single-support phases
and for the impact instant. The experiments give results that are close to those of the simulation.
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Translated from Fundamentalnaya i Prikladnaya Matematika, Vol. 11, No. 8, pp. 5–28, 2005. 相似文献
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V. O. Manturov 《Journal of Mathematical Sciences》2003,113(6):827-840
A method of representing knots, links, and singular knots and links by words in a finite alphabet and so-called d-diagrams is given. A representation of the chord diagram algebra by words in a finite alphabet is considered. This method, unlike coding by Gauss diagrams, allows one to consider knots and links simultaneously. An algorithm for recognition of diagrams of classical knots in terms of d-diagrams is given. Bibliography: 9 titles. 相似文献
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Božidar Kante 《Acta Analytica》2005,20(4):53-63
The topic of this paper is the role played by context in art. In this regard I examine three theories linked to the names of J. Levinson, G. Currie and D. Davies. Levinson’s arguments undermine the structural theory. He finds it objectionable because it makes the individuation of artworks independent of their histories. Secondly, such a consequence is unacceptable because it fails to recognise that works are created rather than discovered. But, if certain general features of provenance are always work-constitutive, as it seems that Levinson is willing to claim, these features must always be essential properties of works. On the other hand, consideration of our modal practice suggests that whether a given general feature of provenance is essential or non-essential depends upon the particular work in question or is “work relative”. D. Davies builds his performance theory on the basis of the critical evaluation of Currie’s action-type hypotheses (ATH). Performances, says Davies, are not to be identified with “basic actions” to which their times belong essentially, but with “doings” that permit of the sorts of variation in modal properties required by the work-relativity of modality. He is also a fierce critic of the contextualist account. Contextualism is in his view unable to reflect the fact that aspects of provenance bear upon our modal judgements with variable force.In the second part of the paper I consider Davies’s “modality principle”. Davies is inclined to defend the claim that labels used for designation of works are rigid designators. Such a view offers a ground for discussion about the historicity of art. What has been meant when people claim that art is an historical concept? I argue that any historical theory implies a two-dimensional notion of “art”. At the end of the paper I suggest that Davies should embrace the theory of contingent identity and not the colocationist view about the relationship that exists between a particular artwork and its physical bearer. 相似文献
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Brown和McCoy在文[1]中建立了(F,Ω)-群的根理论,并由此考察了环的BrownMcCoy-根及其它一些根,根据这一方法,Szsz在文[2]中引进了环的(k,l,m,n)-根,其中k,l,m,n是任意的非负整数,并证明了环的Brown-McCoy根与(1,1,1,1)-根,(1,1 相似文献
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William A. Roche 《Acta Analytica》2010,25(2):243-257
Coherentists on epistemic justification claim that all justification is inferential, and that beliefs, when justified, get
their justification together (not in isolation) as members of a coherent belief system. Some recent work in formal epistemology
shows that “individual credibility” is needed for “witness agreement” to increase the probability of truth and generate a
high probability of truth. It can seem that, from this result in formal epistemology, it follows that coherentist justification
is not truth-conducive, that it is not the case that, under the requisite conditions, coherentist justification increases
the probability of truth and generates a high probability of truth. I argue that this does not follow. 相似文献
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M.F. Cantley 《European Journal of Operational Research》1985,19(3):399-400
We consider two queues in series with input to each queue, which can be controlled by accepting or rejecting arriving customers. The objective is to maximize the discounted or average expected net benefit over a finite or infinite horizon, where net benefit is composed of (random) rewards for entering customers minus holding costs assessed against the customers at each queue. Provided that it costs more to hold a customer at the first queue than at the second, we show that an optimal policy is monotonic in the following senses: Adding a customer to either queue makes it less likely that we will accept a new customer into either queue; moreover moving a customer from the first queue to the second makes it more (less) likely that we will accept a new customer into the first (second) queue. Our model has policy implications for flow control in communication systems, industrial job shops, and traffic-flow systems. We comment on the relation between the control policies implied by our model and those proposed in the communicationa literature. 相似文献
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It is shown how a best linear unbiased estimate (blue) in the additive variety-block setting can be interpreted as a network flow, that is, a function on edges that obeys the Kirkhhoff laws, of minimum square norm. An explicit expression is then obtained for the coefficients of the blue in terms of invariants of the underlying network; specifically, the invariants are: the total number of spanning trees and the number of certain selective yet specific spanning forests with just two trees. The blue is also expressed as a linear combination of bases of paths in a constructive manner. It remains a conjecture as to whether there always exists a basis of paths in which the blue is a convex combination. Consequences to design optimality are explored. 相似文献