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1.
Héctor Jasso-Fuentes Onésimo Hernández-Lerma 《Applied Mathematics and Optimization》2008,57(3):349-369
In this paper we give conditions for (the existence and) several characterizations of overtaking optimal policies for a general class of controlled diffusion processes. Our characterization results are of
a lexicographical type; namely, first we identify the class of so-called canonical policies, and then within this class we
search for policies with some special feature—for instance, canonical policies that in addition maximize the bias.
This research was partially supported by CONACyT grant 45693-F. The research of the first author (HJF) was also supported
by a CONACyT scholarship. 相似文献
2.
R K Shyamasundar 《Proceedings Mathematical Sciences》1979,88(1):1-19
A necessary and sufficient set of conditions is obtained that relates any two context-free grammarsG
1 andG
2 with the property that wheneverG
2 left—or right—coversG
1, the syntax-directed translations (SDT’s) with underlying grammarG
1 is a subset of those with underlying grammarG
2. Also the case thatG
2 left—or right—coversG
1 but the SDT’s with underlying grammarG
1 is not a subset of the SDT’s with underlying grammarG
2 is considered; in this case an algorithm is described to obtain the syntax-directed translation schema (SDTS) with underlying
grammarG
2 to the given SDTS with underlying grammarG
1, if it exists. 相似文献
3.
Using realizations of the positive discrete series representations of the Lie algebra su(1,1) in terms of Meixner—Pollaczek polynomials, the action of su(1,1) on Poisson kernels of these polynomials is considered. In the tensor product of two such representations, two sets of eigenfunctions
of a certain operator can be considered and they are shown to be related through continuous Hahn polynomials. As a result,
a bilinear generating function for continuous Hahn polynomials is obtained involving the Poisson kernel of Meixner—Pollaczek
polynomials; this result is also known as the Burchnall—Chaundy formula. For the positive discrete series representations
of the quantized universal enveloping algebra U
q
(su(1,1)) a similar analysis is performed and leads to a bilinear generating function for Askey—Wilson polynomials involving the Poisson
kernel of Al-Salam and Chihara polynomials.
July 6, 1997. Date accepted: September 23, 1998. 相似文献
4.
Pulse vaccination is an effective strategy for the elimination of infectious diseases. In this paper, we considered an SEIR epidemic model with delay and impulsive vaccination direct at a variable population and analyzed its dynamic behaviors. Using the discrete dynamical system determined by the stroboscopic map, we obtain the exact infection‐free periodic solution of the impulsive epidemic system, further, prove that the infection‐free periodic solution is globally attractive if the vaccination rate is larger than θ* or the length of latent period of disease is larger than τ* or the length of period of impulsive vaccination is smaller than T*. We also prove that a short latent period of the disease (with τ) or a long period of pulsing (with T) or a small pulse vaccination rate (with θ) is sufficient to bring about the disease is uniformly persistent. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
5.
We obtain an explicit formula for the linearization coefficient of the product of two associated q-ultraspherical polynomials in terms of a multiple of a balanced, terminating very-well-poised
10φ9 series. We also discuss the nonnegativity properties of the coefficients as well as some special cases.
2000 Mathematics Subject Classification Primary—33D45; Secondary—33D8
This work was supported in part by an NSERC grant A6197. 相似文献
6.
Jonatan Vasilis 《Geometriae Dedicata》2011,152(1):51-62
Suppose that n cyclically tangent discs with pairwise disjoint interiors are externally tangent to and surround the unit disc. The sharp
ring lemma in two dimensions states that no disc has a radius below c
n
(R
2) = (F
2n−3−1)−1—where F
k
denotes the kth Fibonacci number—and that the lower bound is attained in essentially unique Apollonian configurations. In this article,
generalizations of the ring lemma to three dimensions are discussed, a version of the ring lemma in three dimensions is proved,
and a natural generalization of the extremal two-dimensional configuration—thought to be extremal in three dimensions—is given.
The sharp three-dimensional ring lemma constant of order n is shown to be bounded from below by the two-dimensional constant of order n − 1. 相似文献
7.
V. Boltyanski 《Discrete and Computational Geometry》2001,26(4):527-541
We solve here the Gohberg—Markus—Hadwiger Covering Problem (or, what is the same, the illumination problem ) for compact, convex bodies M\subset R
n
with md M=2 . Moreover, we outline an idea for a complete solution, using md M .
Received August 23, 2000, and in revised form January 22, 2001. Online publication August 9, 2001. 相似文献
8.
Jin-Lin Liu 《Mathematica Slovaca》2012,62(1):25-28
For analytic functions f(z) in the open unit disk U and convex functions g(z) in U, Nunokawa et al. [NUNOKAWA, M.—OWA, S.—NISHIWAKI, J.—KUROKI, K.—HAYAMI, T: Differential subordination and argumental property, Comput. Math. Appl. 56 (2008), 2733–2736] have proved one theorem which is a generalization of the result [POMMERENKE, CH.: On close-toconvex analytic functions, Trans. Amer. Math. Soc. 114 (1965), 176–186]. The object of the present paper is to generalize the theorem due to Nunokawa et al.. 相似文献
9.
The question whether or not the sum of two maximal monotone operators is maximal monotone under Rockafellar’s constraint qualification—that
is, whether or not “the sum theorem” is true—is the most famous open problem in Monotone Operator Theory. In his 2008 monograph
“From Hahn-Banach to Monotonicity”, Stephen Simons asked whether or not the sum theorem holds for the special case of a maximal monotone linear operator and
a normal cone operator of a closed convex set provided that the interior of the set makes a nonempty intersection with the
domain of the linear operator. In this note, we provide an affirmative answer to Simons’ question. In fact, we show that the
sum theorem is true for a maximal monotone linear relation and a normal cone operator. The proof relies on Rockafellar’s formula for the Fenchel conjugate of the sum as well as some
results featuring the Fitzpatrick function.
相似文献
10.
Christiansen 《Constructive Approximation》2008,19(1):1-22
Abstract. We consider the indeterminate Stieltjes moment problem associated with the q -Laguerre polynomials. A transformation of the set of solutions, which has all the classical solutions as fixed points, is
established and we present a method to construct, for instance, continuous singular solutions. The connection with the moment
problem associated with the Stieltjes—Wigert polynomials is studied; we show how to come from q -Laguerre solutions to Stieltjes—Wigert solutions by letting the parameter α —> ∞ , and we explain how to lift a Stieltjes—Wigert solution to a q -Laguerre solution at the level of Pick functions. Based on two generating functions, expressions for the four entire functions
from the Nevanlinna parametrization are obtained. 相似文献
11.
Wolfhard Hansen 《Potential Analysis》2012,36(2):263-273
It is shown that, for α-stable processes (Riesz potentials) or—more generally—for balayage spaces with jumps, “one-radius” results for harmonicity
can be obtained under fairly weak assumptions. 相似文献
12.
DachuanXu GuanghuiLiu 《应用数学学报(英文版)》2003,19(2):289-296
Given a directed graph G and an edge weight function w : A(G)→ R^ , the maximum directed cut problem (MAX DICUT) is that of finding a directed cut δ(S) with maximum total weight. We consider a version of MAX DICUT -- MAX DICUT with given sizes of parts or MAX DICUT WITH GSP -- whose instance is that of MAX DICUT plus a positive integer k, and it is required to find a directed cut δ(S) having maximum weight over all cuts δ(S) with |S| -- k. We present an approximation algorithm for this problem which is based on semidefinite programming (SDP) relaxation. The algorithm achieves the presently best performance guarantee for a range of k. 相似文献
13.
Feature selection for high-dimensional data 总被引:2,自引:0,他引:2
Augusto Destrero Sofia Mosci Christine De Mol Alessandro Verri Francesca Odone 《Computational Management Science》2009,6(1):25-40
This paper focuses on feature selection for problems dealing with high-dimensional data. We discuss the benefits of adopting
a regularized approach with L
1 or L
1–L
2 penalties in two different applications—microarray data analysis in computational biology and object detection in computer
vision. We describe general algorithmic aspects as well as architecture issues specific to the two domains. The very promising
results obtained show how the proposed approach can be useful in quite different fields of application. 相似文献
14.
Ansten Mørch Klev 《Archive for Mathematical Logic》2009,48(7):691-703
Using infinite time Turing machines we define two successive extensions of Kleene’s O{\mathcal{O}} and characterize both their height and their complexity. Specifically, we first prove that the one extension—which we will
call O+{\mathcal{O}^{+}}—has height equal to the supremum of the writable ordinals, and that the other extension—which we will call O++{\mathcal{O}}^{++}—has height equal to the supremum of the eventually writable ordinals. Next we prove that O+{\mathcal{O}^+} is Turing computably isomorphic to the halting problem of infinite time Turing computability, and that O++{\mathcal{O}^{++}} is Turing computably isomorphic to the halting problem of eventual computability. 相似文献
15.
Theprofile of a hypergraph onn vertices is (f
0, f1, ...,f
n) wheref
i denotes the number ofi-element edges. The extreme points of the set of profiles is determined for certain hypergraph classes. The results contain
many old theorems of extremal set theory as particular cases (Sperner. Erdős—Ko—Rado, Daykin—Frankl—Green—Hilton). 相似文献
16.
S. Albeverio Y. -Z. Hu M. Röckner X. Y. Zhou 《Applied Mathematics and Optimization》1999,40(3):341-354
We prove that there exists a diffusion process whose invariant measure is the two-dimensional polymer measure ν
g
. The diffusion is constructed by means of the theory of Dirichlet forms on infinite-dimensional state spaces. We prove the
closability of the appropriate pre-Dirichlet form which is of gradient type, using a general closability result by two of
the authors. This result does not require an integration by parts formula (which does not hold for the two-dimensional polymer
measure ν
g
) but requires the quasi-invariance of ν
g
along a basis of vectors in the classical Cameron—Martin space such that the Radon—Nikodym derivatives (have versions which)
form a continuous process. We also show the Dirichlet form to be irreducible or equivalently that the diffusion process is
ergodic under time translations.
Accepted 16 April 1998 相似文献
17.
Mark Steen 《Acta Analytica》2011,26(2):135-154
Ned Markosian argues (Australasian Journal of Philosophy 76:213-228, 1998a; Australasian Journal of Philosophy 82:332-340, 2004a, The Monist 87:405-428, 2004b) that simples are ‘maximally continuous’ entities. This leads him to conclude that there could be non-particular ‘stuff’
in addition to things. I first show how an ensuing debate on this issue McDaniel (Australasian Journal of Philosophy 81(2):265-275,
2003); Markosian (Australasian Journal of Philosophy 82:332-340, 2004a) ended in deadlock. I attempt to break the deadlock. Markosian’s view entails stuff-thing coincidence, which I show is just
as problematic as the more oft-discussed thing-thing coincidence. Also, the view entails that every particular is only contingently
so. If there is a world W like our own, but with ether, then there would be only one object in W. But, since merely adding ether to a world does not destroy the entities in it, then W contains counterparts of all the entities in the actual world—they just are not things. Hence, if simples are maximally continuous,
then every actual particular is only contingently so. This in turn entails the following disjunction: (i) identity is contingent
or intransitive, or (ii) there are no things at all in the actual world, or (iii) the distinction between stuff and things
is one without a difference. I recommend that we reject this stuff-thing dualism. 相似文献
18.
The L(2, 1)-labeling problem for a graph G is a variation of the standard graph coloring problem. Here, we seek to assign a label (color) to each node of G such that nodes a distance of two apart are assigned unique labels and adjacent nodes receive labels which are at least two
apart. In a previous paper—presented at the 23rd IASTED International Multi-Conference: Parallel and Distributed Computing
and Networks, Innsbruck, Austria—we presented, to the best of our knowledge, the first self-stabilizing algorithm which {Δ
+ 2}-L(2, 1)-labels rooted trees. That algorithm was shown to require an exponential number of moves to stabilize on a global
solution (which is not uncommon in self-stabilizing systems). In this paper, we present two self-stabilizing algorithms which
{Δ + 2}-L(2, 1)-label a given rooted tree T in only O(nh) moves (where h is the height and n is the number of nodes in the tree T) under a central scheduler. We also show how the algorithms may be adapted to unrooted trees, dynamic topology changes, and
consider the correctness of the protocols under the distributed scheduler model. 相似文献
19.
Torsten Ekedahl 《Arkiv f?r Matematik》1984,22(1):185-239
Summary Due to the length this work is published in two parts. The second part will appear in Vol 23: 1 of this journal.
Part 1 has the subtitle “Duality for the de Rham—Witt complex” and Part 2 is entitled “A Künneth formula for the Hodge—Witt complex”. 相似文献
20.
Pauline Coolen-Schrijner Erik A. van Doorn 《Methodology and Computing in Applied Probability》2006,8(4):449-465
This paper is concerned with the circumstances under which a discrete-time absorbing Markov chain has a quasi-stationary distribution.
We showed in a previous paper that a pure birth-death process with an absorbing bottom state has a quasi-stationary distribution—actually
an infinite family of quasi-stationary distributions— if and only if absorption is certain and the chain is geometrically
transient. If we widen the setting by allowing absorption in one step (killing) from any state, the two conditions are still necessary, but no longer sufficient. We show that the birth–death-type of behaviour
prevails as long as the number of states in which killing can occur is finite. But if there are infinitely many such states,
and if the chain is geometrically transient and absorption certain, then there may be 0, 1, or infinitely many quasi-stationary
distributions. Examples of each type of behaviour are presented. We also survey and supplement the theory of quasi-stationary
distributions for discrete-time Markov chains in general.
相似文献