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1.
Jonathan Stavi 《Israel Journal of Mathematics》1973,15(1):31-43
A problem of Gaifman about strongly and weakly defined Boolean terms is solved by finding a Boolean algebra ℱ with a complete
subalgebra ℰ such that some element of ℱ not in ℰ can be obtained from elements of ℰ by meets and joins in the normal completion
of ℱ. 相似文献
2.
It is known matroids obtained from a totally free uniform matroid U
2,n
by a sequence of segment–cosegment and cosegment–segment exchanges are totally free (Geelen et al., in J Combin Theory Ser
B 92:55–67, 2004). In this paper, we prove matroids obtained from any totally free matroid by a sequence of segment–cosegment
and cosegment–segment exchanges are also totally free. 相似文献
3.
Ath Kehagias 《Rendiconti del Circolo Matematico di Palermo》2003,52(2):322-350
In this paper we study two fuzzy hyperoperations, denoted by ⋎ (which can be seen as a generalization of ∨) and ⋏ (which can
be seen as a generalization of ∧). ⋎ is obtained from a family of crisp ∨;
p
hyperoperations and ⋏ is obtained from a family of crisp ∧
p
hyperoperations. The hyperstructure (X, ⋎, ∧) resembles ahyperlattice and the hyperstructure (X, ∨, ⋏) resembles adual hyperlattice 相似文献
4.
In this paper, we consider a Cauchy problem of the time fractional diffusion equation (TFDE). Such problem is obtained from
the classical diffusion equation by replacing the first-order time derivative by the Caputo fractional derivative of order
α (0 < α ≤ 1). We show that the Cauchy problem of TFDE is severely ill-posed and further apply a new regularization method to solve
it based on the solution given by the Fourier method. Convergence estimates in the interior and on the boundary of solution
domain are obtained respectively under different a-priori bound assumptions for the exact solution and suitable choices of
regularization parameters. Finally, numerical examples are given to show that the proposed numerical method is effective. 相似文献
5.
Theoretical analysis of the velocity field, stress field and vortex sheet of generalized second order fluid with fractional anomalous diffusion 总被引:1,自引:0,他引:1
The velocity field of generalized second order fluid with fractional anomalous diiusion caused by a plate moving impulsively
in its own plane is investigated and the anomalous diffusion problems of the stress field and vortex sheet caused by this
process are studied. Many previous and classical results can be considered as particular cases of this paper, such as the
solutions of the fractional diffusion equations obtained by Wyss; the classical Rayleigh’s time-space similarity solution;
the relationship between stress field and velocity field obtained by Bagley and co-worker and Podlubny’s results on the fractional
motion equation of a plate. In addition, a lot of significant results also are obtained. For example, the necessary condition
for causing the vortex sheet is that the time fractional diffusion index β must be greater than that of generalized second
order fluid α; the establiihment of the vorticity distribution function depends on the time history of the velocity profile
at a given point, and the time history can be described by the fractional calculus. 相似文献
6.
Masaaki Sibuya 《Annals of the Institute of Statistical Mathematics》1979,31(1):373-390
Summary In this paper we introduce and study new probability distributions named “digamma” and “trigamma” defined on the set of all
positive integers. They are obtained as limits of the zero-truncated Type B3 generalized hypergeometric distributions (inverse
Pólya-Eggenberger or negative binomial beta distributions), and also by compounding the logarithmic series distributions.
The family of digamma distributions has the logarithmic series as a limit and the trigamma as another limit. The trigamma
distributions are very close to the zeta (Zipf) distributions. Thus, our new distributions are useful as substitutes of the
logarithmic series when the observed frequency data have such a long tail that cannot be fitted by the latter distributions.
In the beginning sections we summarize properties of the Type B3 generalized hypergeometric distributions. It is emphasized
that the distributions are obtained by compounding a Poisson distribution by “gamma product-ratio” distributions. 相似文献
7.
Nathan Jones 《Mathematische Annalen》2009,345(3):685-710
We compute the averages over elliptic curves of the constants occurring in the Lang–Trotter conjecture, the Koblitz conjecture,
and the cyclicity conjecture. The results obtained confirm the consistency of these conjectures with the corresponding “theorems
on average” obtained recently by various authors. 相似文献
8.
M. Fabrizio G. Matarazzo M. Pecoraro 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2011,24(2):1013-1026
In this paper, by an extension of the Ginzburg–Landau theory, we propose a mathematical model describing hard magnets within
which we are able to explore the para–ferromagnetic transition and by using the Landau–Lifshitz–Gilbert equation, to study
the 3D evolution of magnetic field. Finally, the hysteresis loops are obtained and represented by numerical implementations. 相似文献
9.
Given an open bounded connected subset Ω of ℝn, we consider the overdetermined boundary value problem obtained by adding both zero Dirichlet and constant Neumann boundary
data to the elliptic equation −div(A(|∇u|)∇u)=1 in Ω. We prove that, if this problem admits a solution in a suitable weak sense, then Ω is a ball. This is obtained under
fairly general assumptions on Ω and A. In particular, A may be degenerate and no growth condition is required. Our method of proof is quite simple. It relies on a maximum principle
for a suitable P-function, combined with some geometric arguments involving the mean curvature of ∂Ω. 相似文献
10.
Using ‘fusion’ methods on finite semifields, a variety of partitions (flocks) of Segre varieties by caps are obtained. The
partitions arise from semifield planes and are thus called “semifield flat flocks”. Furthermore, the finite transitive semifield
flat flocks are completely determined. 相似文献
11.
A. Khatamov 《Mathematical Notes》2000,67(4):516-522
We obtain an instance of the multidimensional analogs of the classical direct and converse Jackson and Bernshtein-Vallée-Poussin
theorems (a version stronger than those obtained by S. M. Nikol’skii) and significant generalizations of these theorems to
polynomial approximations of functions of real variables from Nikol’skii and Besov spaces on bounded domains with Lipschitzian
boundary. The direct theorem concerning the Nikol’skii spaces was previously obtained by Yu. A. Brudnyi and generalized to
joint polynomial approximations of functions and their derivatives by B. N. Konovalov.
Translated fromMatematicheskie Zametki, Vol. 67, No. 4, pp. 608–615, April, 2000. 相似文献
12.
Miklavž Mastinšek 《Mathematical Methods of Operations Research》2006,64(2):227-236
The paper deals with the problem of discrete–time delta hedging and discrete-time option valuation by the Black–Scholes model. Since in the Black–Scholes model the hedging is continuous, hedging errors appear when applied to discrete trading. The hedging error is considered and a discrete-time adjusted Black–Scholes–Merton equation is derived. By anticipating the time sensitivity of delta in many cases the discrete-time delta hedging can be improved and more accurate delta values dependent on the length of the rebalancing intervals can be obtained. As an application the discrete-time trading with transaction costs is considered. Explicit solution of the option valuation problem is given and a closed form delta value for a European call option with transaction costs is obtained. 相似文献
13.
14.
We propose a Moreau–Yosida regularization for maximal monotone operators of type (D), in non-reflexive Banach spaces. It generalizes
the classical Moreau–Yosida regularization as well as Brezis–Crandall–Pazy’s extension of this regularization to strictly
convex (reflexive) Banach spaces with strictly convex duals. Our main results are obtained by making use of recent results
by the authors on convex representations of maximal monotone operators in non-reflexive Banach spaces. 相似文献
15.
Let τ be some triangulation of a planar polygonal domain Ω. Given a smooth functionu, we construct piecewise polynomial functionsv∈C
ρ(Ω) of degreen=3 ρ for ρ odd, andn=3ρ+1 for ρ even on a subtriangulation τ3 of τ. The latter is obtained by subdividing eachT∈ρ into three triangles, andv/T is a composite triangular finite element, generalizing the classicalC
1 cubic Hsieh-Clough-Tocher (HCT) triangular scheme. The functionv interpolates the derivatives ofu up to order ρ at the vertices of τ. Polynomial degrees obtained in this way are minimal in the family of interpolation schemes
based on finite elements of this type. 相似文献
16.
The notion of a generalized action of the group ℤ∞ on a topological space generated by an arbitrary countable family of pairwise commuting homeomorphisms is introduced, and
a study of generalized orbits under such actions is given. Analogues of Takens’ theorems on the genericity of the maximal
and minimal ɛ-equivalences for such actions are obtained. 相似文献
17.
Ricardo Abreu Blaya Juan Bory Reyes Tania Moreno García 《Complex Analysis and Operator Theory》2007,1(3):301-305
In the present paper we provide some conditions of a geometrical character for continuous extendibility of the Clifford–Cauchy
transform to the boundary of a domain in the Euclidean space of higher dimensions if its density satisfies a H?lder condition.
The criterion obtained in this work is an extension to a very general class of domains of a result, which has already become
classical, obtained by Viorel Iftimie, who proved in 1965, for the case of a domain with compact Liapunov boundary, that the
Clifford–Cauchy transform has H?lder–continuous limit values for any H?lder–continuous density.
Received: August 15, 2006. Accepted: November 2, 2006. 相似文献
18.
The following steps are suggested for smoothing the occurrence patterns in a clustered space–time process, in particular the
data from an earthquake catalogue. First, the original data is fitted by a temporal version of the ETAS model, and the occurrence
times are transformed by using the cumulative form of the fitted ETAS model. Then the transformed data (transformed times
and original locations) is smoothed by a space–time kernel with bandwidth obtained by optimizing a naive likelihood cross-validation.
Finally, the estimated intensity for the original data is obtained by back-transforming the estimated intensity for the transformed
data. This technique is used to estimate the intensity for earthquake occurrence data for associated with complex sequences
of events off the East Coast of Tohoku district, northern Japan. The intensity so obtained is compared to the conditional
intensity estimated from a full space–time ETAS model for the same data. 相似文献
19.
In this paper, existence results for a fourth-order nonlinear system are obtained. Both classical and vector versions of the
Krasnosel’skiĭ’s fixed point theorem are used and a comparison of the obtained results to those from the literature is provided. 相似文献
20.
A theorem on the presentability of a multiple integral as a linear form in 1, ζ(3), ζ(5),..., ζ(2k − 1) over ℚ is proved. This theorem refines the results recently obtained by D. Vasiliev, V. Zudilin, and S. Zlobin.
__________
Translated from Fundamentalnaya i Prikladnaya Matematika, Vol. 11, No. 6, pp. 143–178, 2005. 相似文献