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1.
With a plane curve singularity one associates a multi-index filtration on the ring of germs of functions of two variables
defined by the orders of a function on irreducible components of the curve. The Poincaré series of this filtration turns out
to coincide with the Alexander polynomial of the curve germ. For a finite set of divisorial valuations on the ring corresponding
to some components of the exceptional divisor of a modification of the plane, in a previous paper there was obtained a formula
for the Poincaré series of the corresponding multi-index filtration similar to the one associated with plane germs. Here we
show that the Poincaré series of a set of divisorial valuations on the ring of germs of functions of two variables defines
“the topology of the set of the divisors” in the sense that it defines the minimal resolution of this set up to combinatorial
equivalence. For the plane curve singularity case, we also give a somewhat simpler proof of the statement by Yamamoto which
shows that the Alexander polynomial is equivalent to the embedded topology. 相似文献
2.
We describe the so-called method of virtual components for tight wavelet framelets to increase their approximation order and vanishing moments in the multivariate setting. Two examples of the virtual components for tight wavelet frames based on bivariate box splines on three or four direction mesh are given. As a byproduct, a new construction of tight wavelet frames based on box splines under the quincunx dilation matrix is presented. 相似文献
3.
Angelo Miele 《Journal of Optimization Theory and Applications》2010,147(3):483-490
On the occasion of the 50th anniversary of the theorem of the image trajectories in the Earth-Moon space, the author revisits
the theorem and clarifies the relation between the class of image trajectories and the class of symmetric free-return trajectories,
which were employed in the Apollo program. In a nutshell, the symmetric free-return trajectories are those image trajectories
that intersect the Earth-Moon axis orthogonally at some point above the far side of the Moon. Optimization implications are
pointed out. 相似文献
4.
This paper obtains some equivalent conditions about the asymptotics for the density of the supremum of a random walk with
light-tailed increments in the intermediate case. To do this, the paper first corrects the proofs of some existing results
about densities of random sums. On the basis of the above results, the paper obtains some equivalent conditions about the
asymptotics for densities of ruin distributions in the intermediate case and densities of infinitely divisible distributions.
In the above studies, some differences and relations between the results on a distribution and its corresponding density can
be discovered.
相似文献
5.
Yasuki Isozaki 《Journal of Theoretical Probability》2009,22(1):57-81
We study asymptotic estimates that contain the hitting time and the hitting place of a half-line by a two-dimensional random
walk. Fluctuation identities are used without resorting to pair annihilation but by interchanging summation and integration.
The same method applies to the hitting of the half-space by a one-dimensional random walk.
The author was supported by a grant (no. 18740053) of Japan Society for the Promotion of Science. 相似文献
6.
How to get the timing right. A computational model of the effects of the timing of contacts on team cohesion in demographically diverse teams 总被引:1,自引:0,他引:1
Lau and Murnighan’s faultline theory explains negative effects of demographic diversity on team performance as consequence of strong demographic faultlines. If demographic differences between group members are correlated across various dimensions, the team is likely to show a “subgroup split” that inhibits communication and effective collaboration between team members. Our paper proposes a rigorous formal and computational reconstruction of the theory. Our model integrates four elementary mechanisms of social interaction, homophily, heterophobia, social influence and rejection into a computational representation of the dynamics of both opinions and social relations in the team. Computational experiments demonstrate that the central claims of faultline theory are consistent with the model. We show furthermore that the model highlights a new structural condition that may give managers a handle to temper the negative effects of strong demographic faultlines. We call this condition the timing of contacts. Computational analyses reveal that negative effects of strong faultlines critically depend on who is when brought in contact with whom in the process of social interactions in the team. More specifically, we demonstrate that faultlines have hardly negative effects when teams are initially split into demographically homogeneous subteams that are merged only when a local consensus has developed. 相似文献
7.
John R. Akeroyd 《Arkiv f?r Matematik》2011,49(1):1-16
It is shown that for any t, 0<t<∞, there is a Jordan arc Γ with endpoints 0 and 1 such that
G\{1} í \mathbbD:={z:|z| < 1}\Gamma\setminus\{1\}\subseteq\mathbb{D}:=\{z:|z|<1\}
and with the property that the analytic polynomials are dense in the Bergman space
\mathbbAt(\mathbbD\G)\mathbb{A}^{t}(\mathbb{D}\setminus\Gamma)
. It is also shown that one can go further in the Hardy space setting and find such a Γ that is in fact the graph of a continuous
real-valued function on [0,1], where the polynomials are dense in
Ht(\mathbbD\G)H^{t}(\mathbb{D}\setminus\Gamma)
; improving upon a result in an earlier paper. 相似文献
8.
Marcos Singer Patricio Donoso Garo Konstantinidis 《Annals of Operations Research》2009,169(1):131-147
The hockey-stick pattern faced by suppliers consists of sales spikes at the end of each period. One of its causes is the information
asymmetry that favors the retailer, who has better knowledge about the stochastic consumer demand. Because of delayed purchases,
the supplier is induced to offer promotions, allowing the retailer to forward-buy at low prices. We model this situation as
an infinitely repeated game, where each stage-game is subject to imperfect information. Drawing from the Nash equilibrium,
we express sales and inventories in terms of demand, cost and the strategies players may adopt, and derive the conditions
for a cooperative equilibrium. 相似文献
9.
Regularization techniques based on the Golub-Kahan iterative bidiagonalization belong among popular approaches for solving large ill-posed problems. First, the original problem is projected onto a lower dimensional subspace using the bidiagonalization algorithm, which by itself represents a form of regularization by projection. The projected problem, however, inherits a part of the ill-posedness of the original problem, and therefore some form of inner regularization must be applied. Stopping criteria for the whole process are then based on the regularization of the projected (small) problem. In this paper we consider an ill-posed problem with a noisy right-hand side (observation vector), where the noise level is unknown. We show how the information from the Golub-Kahan iterative bidiagonalization can be used for estimating the noise level. Such information can be useful for constructing efficient stopping criteria in solving ill-posed problems. 相似文献
10.
In this paper we obtain a new regularity criterion for weak solutions to the 3D MHD equations. It is proved that if
div( \fracu|u|) \mathrm{div}( \frac{u}{|u|}) belongs to
L\frac21-r( 0,T;[(X)\dot]r( \mathbbR3) ) L^{\frac{2}{1-r}}( 0,T;\dot{X}_{r}( \mathbb{R}^{3}) ) with 0≤r≤1, then the weak solution actually is regular and unique. 相似文献
11.
In this paper we consider approximations of the occupation measure of the Fractional Brownian motion by means of some functionals
defined on regularizations of the paths. In a previous article Berzin and León proved a cylindrical convergence to a Wiener
process of conveniently rescaled functionals. Here we show the tightness of the approximation in the space of continuous functions
endowed with the topology of uniform convergence on compact sets. This allows us to simplify the identification of the limit. 相似文献
12.
Equations for the Missing Boundary Values in the Hamiltonian Formulation of Optimal Control Problems
Vicente Costanza Pablo S. Rivadeneira Ruben D. Spies 《Journal of Optimization Theory and Applications》2011,149(1):26-46
Partial differential equations for the unknown final state and initial costate arising in the Hamiltonian formulation of regular
optimal control problems with a quadratic final penalty are found. It is shown that the missing boundary conditions for Hamilton’s
canonical ordinary differential equations satisfy a system of first-order quasilinear vector partial differential equations
(PDEs), when the functional dependence of the H-optimal control in phase-space variables is explicitly known. Their solutions are computed in the context of nonlinear systems
with ℝ
n
-valued states. No special restrictions are imposed on the form of the Lagrangian cost term. Having calculated the initial
values of the costates, the optimal control can then be constructed from on-line integration of the corresponding 2n-dimensional Hamilton ordinary differential equations (ODEs). The off-line procedure requires finding two auxiliary n×n matrices that generalize those appearing in the solution of the differential Riccati equation (DRE) associated with the linear-quadratic
regulator (LQR) problem. In all equations, the independent variables are the finite time-horizon duration T and the final-penalty matrix coefficient S, so their solutions give information on a whole two-parameter family of control problems, which can be used for design purposes.
The mathematical treatment takes advantage from the symplectic structure of the Hamiltonian formalism, which allows one to
reformulate Bellman’s conjectures concerning the “invariant-embedding” methodology for two-point boundary-value problems.
Results for LQR problems are tested against solutions of the associated differential Riccati equation, and the attributes
of the two approaches are illustrated and discussed. Also, nonlinear problems are numerically solved and compared against
those obtained by using shooting techniques. 相似文献
13.
Piero D’Ancona Vittoria Pierfelice Fulvio Ricci 《Journal of Fourier Analysis and Applications》2010,16(2):294-310
The dispersive properties of the wave equation u
tt
+Au=0 are considered, where A is either the Hermite operator −Δ+|x|2 or the twisted Laplacian −(∇
x
−iy)2/2−(∇
y
+ix)2/2. In both cases we prove optimal L
1−L
∞ dispersive estimates. More generally, we give some partial results concerning the flows exp (itL
ν
) associated to fractional powers of the twisted Laplacian for 0<ν<1. 相似文献
14.
In this paper, we first consider difference equations with several delays in the neutral term of the form * $$\Delta\left(y_{n}+\sum_{i=1}^{L}p_{i}y_{n-{k_{i}}}-\sum_{j=1}^{M}r_{j}y_{n-{\rho_{j}}}\right)+q_{n}y_{n-\tau}=0\quad \mbox{for}\ n\in\mathbb{Z}^{+}(0),$$ study various cases of coefficients in the neutral term and obtain the asymptotic behavior for non-oscillatory solution of (*) under some hypotheses. Moreover, we consider reaction-diffusion difference equations with several delays in the neutral term of the form $$\begin{array}{l}\Delta_{1}\left(u_{n,m}+\displaystyle \sum_{i=1}^{L}p_{i}u_{n-{k_{i}},m}-\displaystyle \sum_{j=1}^{M}r_{j}u_{n-{\rho_{j}},m}\right)+q_{n,m}u_{n-\tau,m}\\[18pt]\quad {}=a^{2}\Delta_{2}^{2}u_{n+1,m-1}\end{array}$$ for (n,m)∈?+(0)×Ω, study various cases of coefficients in the neutral term and obtain the asymptotic behavior for non-oscillatory solution under some hypotheses. 相似文献
15.
Saidbek S. Mirakhmedov Sherzod M. Mirakhmedov 《Journal of Theoretical Probability》2010,23(3):904-919
We consider a scheme of equiprobable allocation of particles into cells by sets. An Edgeworth-type asymptotic expansion in
the local central limit theorem for the number of empty cells left after allocation of all sets of particles is derived. 相似文献
16.
Edoardo Mollona Andrea Marcozzi 《Computational & Mathematical Organization Theory》2009,15(2):109-126
The increasing knowledge intensity of jobs, typical of a knowledge economy, highlights the role of firms as integrators of
know how and skills. As economic activity becomes mainly intellectual and requires the integration of specific and idiosyncratic
skills, firms need to allocate skills to tasks and traditional hierarchical control may result increasingly ineffective. In
this work, we explore under what circumstances networks of agents, which bear specific skills, may self-organize in order
to complete tasks. We use a computer simulation approach and investigate how local interaction of agents, endowed with skills
and individual decision-making rules, may produce aggregate network structure able to perform tasks. To design algorithms
that mimic individual decision-making, we borrow from computer science literature and, in particular, from studies addressing
protocols that produce cooperation in P2P networks. We found that self-organization depends on imitation of successful peers,
competition among agents holding specific skills, and the structural features of, formal or informal, organizational networks
embedding both professionals, holding skills, and project managers, holding access to jobs.
相似文献
Andrea MarcozziEmail: |
17.
Heleno Cunha Francisco Dutenhefner Nikolay Gusevskii Rafael Santos Thebaldi 《Journal of Geometric Analysis》2012,22(2):295-319
We consider the space M\mathcal{M} of ordered m-tuples of distinct complex geodesics in complex hyperbolic 2-space,
H\mathbbC2{\rm\bf H}_{\mathbb{C}}^{2}, up to its holomorphic isometry group PU(2,1). One of the important problems in complex hyperbolic geometry is to construct
and describe the moduli space for M\mathcal{M}. This is motivated by the study of the deformation space of groups generated by reflections in complex geodesics. In the
present paper, we give the complete solution to this problem. 相似文献
18.
19.
We consider a MAP/G/1 retrial queue where the service time distribution has a finite exponential moment. We derive matrix differential equations
for the vector probability generating functions of the stationary queue size distributions. Using these equations, Perron–Frobenius
theory, and the Karamata Tauberian theorem, we obtain the tail asymptotics of the queue size distribution. The main result
on light-tailed asymptotics is an extension of the result in Kim et al. (J. Appl. Probab. 44:1111–1118, 2007) on the M/G/1 retrial queue. 相似文献
20.
We reconstruct Cohen, March and Olsen’s Garbage Can model of organizational choice as an agent-based model. In the original
model, the members of an organization can postpone decision-making. We add another means for avoiding making decisions, that
of buck-passing difficult problems to colleagues. We find that selfish individual behavior, such as postponing decision-making
and buck-passing, does not necessarily imply dysfunctional consequences for an organization. 相似文献